MPT 1314
PERFORMANCE SPECIFICATION
Transmitting and receiving
equipment for use in the PMR
Local Communication Service
Revised and reprinted December 1997
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MPT 1314:1997
 Crown Copyright 1996
First published November 1979
Revised and reprinted July 1994
Revised and reprinted December 1996
Revised and reprinted December 1997
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MPT 1314:1997
Blank page
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MPT 1314:1997
Contents
FOREWORD ................................................................................................................................................. 8
1 GENERAL ................................................................................................................................................ 10
1.1 Scope of specification ................................................................................................................. 10
1.2 Licensee's responsibility .............................................................................................................. 10
1.3 Operating frequencies ................................................................................................................. 10
1.4 Selective signalling ...................................................................................................................... 10
1.5 Auxiliary test equipment ............................................................................................................. 11
1.6 Auxiliary information .................................................................................................................... 11
1.7 Construction ................................................................................................................................ 11
1.8 Labelling ...................................................................................................................................... 11
1.9 Controls ....................................................................................................................................... 11
1.10 Declarations by the manufacturer ............................................................................................. 11
1.11 Classes of emission .................................................................................................................. 12
1.12 Synthesisers and PLL systems ................................................................................................. 12
2 TEST CONDITIONS, POWER SOURCES AND AMBIENT TEMPERATURES ...................................... 12
2.1 Normal and extreme test conditions............................................................................................ 12
2.2 Test power source ....................................................................................................................... 12
2.3 Normal test conditions ................................................................................................................. 12
2.3.1 Normal temperature and humidity ............................................................................ 12
2.3.2 Normal test power source ......................................................................................... 13
2.4 Extreme test conditions ............................................................................................................... 13
2.4.1 Extreme temperatures .............................................................................................. 13
2.4.2 Extreme test source voltages ................................................................................... 13
2.5 Procedure for tests at extreme temperatures ............................................................................. 13
2.5.1 Procedure for equipment designed for continuous operation ................................... 14
2.5.2 Procedure for equipment designed for intermittent operation................................... 14
3 ELECTRICAL TEST CONDITIONS ......................................................................................................... 14
3.1 Normal test modulation ............................................................................................................... 14
3.1.1 Equipment employing speech modulation ................................................................ 14
3.1.2 Equipment employing selective signalling only ......................................................... 14
3.2 Artificial antenna .......................................................................................................................... 15
3.3 Transmitter automatic shut-off facility. ........................................................................................ 15
3.4 Arrangement for test signals at the input of the transmitter ........................................................ 15
3.5 Arrangements for test signals at the input of the receiver ........................................................... 15
3.6 Arrangements for test signals at the input of the receiver via a test fixture or a test antenna .... 15
3.7 Receiver mute or squelch facility................................................................................................. 15
3.8 Receiver rated audio output power ............................................................................................. 15
3.9 Test of equipment with a duplex filter .......................................................................................... 16
3.10 Test sites and general arrangements for measurements involving the use of radiated fields .. 16
3.10.1 Open air test site ..................................................................................................... 16
3.10.2 Indoor test site ........................................................................................................ 17
3.10.3 Anechoic chamber .................................................................................................. 18
3.10.4 Stripline arrangement.............................................................................................. 20
3.11 Standard position ...................................................................................................................... 21
3.12 Acoustic coupler ........................................................................................................................ 22
3.12.1 General ................................................................................................................... 22
3.12.2 Description .............................................................................................................. 22
3.12.3 Calibration ............................................................................................................... 22
3.13 Test antenna ............................................................................................................................. 23
3.14 Substitution antenna .................................................................................................................. 23
3.15 Test fixture ................................................................................................................................ 24
3.15.1 Description .............................................................................................................. 24
3.15.2 Calibration ............................................................................................................... 24
3.15.3 Mode of use ............................................................................................................ 25
3.16 Bibliography ............................................................................................................................... 25
4 TRANSMITTER ........................................................................................................................................ 25
4.1 Frequency error ........................................................................................................................... 25
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MPT 1314:1997
4.1.1 Definition .................................................................................................................. 25
4.1.2 Method of measurement .......................................................................................... 25
4.1.3 Limits ...................................................................................................................... 26
4.2 Carrier power (conducted) .......................................................................................................... 26
4.2.1 Definitions ................................................................................................................. 26
4.2.2 Method of measurement .......................................................................................... 26
4.2.3 Limits ...................................................................................................................... 26
4.3 Effective radiated power (field strength) ..................................................................................... 26
4.3.1 Definitions ................................................................................................................. 27
4.3.2 Methods of measurement ........................................................................................ 27
4.3.3 Method of measurements of maximum and average effective radiated power
under extreme test conditions ...................................................................... 29
4.3.4 Limits ...................................................................................................................... 29
4.4 Frequency deviation.................................................................................................................... 29
4.4.1 Maximum permissible frequency deviation .............................................................. 29
4.5 Adjacent channel power ............................................................................................................. 30
4.5.1 Definition .................................................................................................................. 30
4.5.2 Method of measurement .......................................................................................... 30
4.5.3 Limit ...................................................................................................................... 31
4.6 Power measuring receiver specification ..................................................................................... 31
4.6.1 General..................................................................................................................... 31
4.6.2 IF filter ...................................................................................................................... 31
4.6.3 Oscillator and amplifier ............................................................................................. 33
4.6.4 Attenuation indicator ................................................................................................. 33
4.6.5 Level indicators ........................................................................................................ 33
4.7 Spurious emissions .................................................................................................................... 33
4.7.1 Definition .................................................................................................................. 33
4.7.2 Method of measuring the power level in a specified load......................................... 34
4.7.3 Methods of measuring the effective radiated power ................................................ 34
4.7.4 Limits ...................................................................................................................... 37
4.8 Intermodulation attenuation ........................................................................................................ 37
4.8.1 Definition .................................................................................................................. 37
4.8.2 Method of measurement .......................................................................................... 37
4.8.3 Limits ...................................................................................................................... 38
4.9 Transient frequency behaviour of the transmitter ....................................................................... 39
4.9.1 Definitions ................................................................................................................. 39
4.9.2 Method of measurement .......................................................................................... 40
4.9.3 Limits ...................................................................................................................... 41
4.9.4 Test discriminator ..................................................................................................... 43
5 RECEIVER ............................................................................................................................................... 43
5.1 Maximum usable sensitivity (conducted) .................................................................................... 43
5.1.1 Definition .................................................................................................................. 43
5.1.2 Method of measurement .......................................................................................... 43
5.1.3 Limits ...................................................................................................................... 43
5.2 Average usable sensitivity expressed as a field strength ........................................................... 44
5.2.1 Definition .................................................................................................................. 44
5.2.2 Method of measurement under normal test conditions ............................................ 44
5.2.3 Method of measurement under extreme test conditions .......................................... 45
5.2.4 Limits ...................................................................................................................... 45
5.2.5 Degradation measurements ..................................................................................... 45
5.3 Amplitude characteristic of the receiver ...................................................................................... 46
5.3.1 Definition .................................................................................................................. 46
5.3.2 Method of measurement .......................................................................................... 47
5.3.3 Limit ...................................................................................................................... 47
5.4 Co-channel rejection ................................................................................................................... 47
5.4.1 Definition .................................................................................................................. 47
5.4.2 Method of measurement .......................................................................................... 47
5.4.3 Limit ...................................................................................................................... 48
5.5 Adjacent channel selectivity........................................................................................................ 48
5.5.1 Definition .................................................................................................................. 48
5.5.2 Equipment with an external antenna connector ....................................................... 49
5.5.3 Equipment without an external antenna connector .................................................. 49
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MPT 1314:1997
5.6 Spurious response rejection ........................................................................................................ 50
5.6.1 Definition ................................................................................................................... 50
5.6.2 Introduction to the method of measurement ............................................................. 50
5.6.3 Equipment with an external antenna connector ........................................................ 51
5.6.4 Equipment without an external antenna connector ................................................... 53
5.7 Intermodulation response rejection ............................................................................................. 55
5.7.1 Definition ................................................................................................................... 55
5.7.2 Equipment with an external antenna connector ........................................................ 55
5.7.3 Equipment without an external antenna connector ................................................... 56
5.8 Blocking or desensitisation .......................................................................................................... 57
5.8.1 Definition ................................................................................................................... 57
5.8.2 Equipment with an external antenna connector ........................................................ 57
5.8.3 Equipment without an external antenna connector ................................................... 58
5.9 Spurious radiations ...................................................................................................................... 59
5.9.1 Definition ................................................................................................................... 59
5.9.2 Method of measuring the power level in a specified load ......................................... 59
5.9.3 Methods of measuring the effective radiated power ................................................. 59
5.9.4 Limits ...................................................................................................................... 62
6 REQUIREMENTS FOR EQUIPMENT EMPLOYING SELECTIVE SIGNALLING .................................... 62
6.1 General........................................................................................................................................ 62
6.2 Calling indicator ........................................................................................................................... 62
6.3 Reset ........................................................................................................................................... 62
6.4 Reset time ................................................................................................................................... 62
6.5 Normal coded test signal ............................................................................................................. 62
6.5.1 Equipment employing sequential tone signalling ...................................................... 63
6.5.2 Equipment employing bit signalling ........................................................................... 63
6.6 Encoder ....................................................................................................................................... 63
6.7 Facilities for access ..................................................................................................................... 63
6.8 Transmitter adjacent channel power ........................................................................................... 63
6.8.1 Definition ................................................................................................................... 63
6.8.2 Method of measurement ........................................................................................... 63
6.8.3 Limit ...................................................................................................................... 63
6.9 Reference sensitivity (response) ................................................................................................. 64
6.9.1 Definition ................................................................................................................... 64
6.10 Maximum usable sensitivity (responses, conducted) ................................................................ 64
6.10.1 Definition ................................................................................................................. 64
6.10.2 Method of measurement ......................................................................................... 64
6.10.3 Limits ...................................................................................................................... 64
6.11 Maximum usable sensitivity (responses, field strength) ............................................................ 64
6.11.1 Definition ................................................................................................................. 65
6.11.2 Test conditions ........................................................................................................ 65
6.11.3 Test procedure ........................................................................................................ 65
6.11.4 Limit ...................................................................................................................... 66
6.12 Adjacent channel selectivity ...................................................................................................... 66
6.12.1 Definition ................................................................................................................. 66
6.12.2 Method of measurement ......................................................................................... 66
6.12.3 Limits ...................................................................................................................... 67
7 ACCURACY OF MEASUREMENTS ........................................................................................................ 67
8 INTERPRETATION OF THIS SPECIFICATION ...................................................................................... 67
ANNEX A: GUIDANCE ON THE USE OF RADIATION TEST SITES ........................................................ 69
A.1 Measuring distance ..................................................................................................................... 69
A.2 Test antenna ............................................................................................................................... 69
A.3 Substitution antenna ................................................................................................................... 69
A.4 Artificial antenna ......................................................................................................................... 69
A.5 Auxiliary cables ........................................................................................................................... 69
A.6 Identification of radiated components ......................................................................................... 69
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MPT 1314:1997
FOREWORD
It is a requirement of the Wireless Telegraphy Act 1949 that no radio apparatus shall be installed or used
in the United Kingdom except under the authority granted by the Secretary of State. It is a condition of this
authority that the performance of the apparatus must meet certain minimum standards. These minimum
standards of performance are given in specifications prepared by the Radiocommunications Agency in
consultation with the relevant manufacturers.
Applicants who wish to submit equipment for type approval testing should apply to one of the accredited
test houses. Guidance for applicants is given in the RA Information Sheet ‘RA 207 (Rev 1): Type
Approval - UK Type Approval Requirements for Land Mobile and Maritime Mobile Radiocommunications
Equipment’. This is available on a single copy basis free from the RA Information & Library Service.
Equipment will be considered for approval purposes either:
a)
by direct compliance with MPT 1314 or;
b)
by compliance with a national standard or government regulation of any Member State of the
European Community, or any Member State which is contracting party to the EEA Agreement or;
c)
by compliance with any relevant international standard or regulation recognised in a member State
of the European Community, or a Member Sate which is a contracting party to the EEA Agreement;
d)
and, where appropriate, by compliance with manufacturing rules and procedures of a Member State
of the European Communities, or a Member State which is a contracting party to the EEA
Agreement, relating to quality control operations during manufacture of the equipment where they
form part of a standard or technical regulations in a) or c) as above;
provided that in case b) or c) the regulation is deemed to comply with MPT 1314.
The results of tests to such a standard will be taken into consideration if carried out by authorised and
accredited test houses in accordance with ISO guides 25 and 38 or EN45001 and EN45002 or a national
standard conforming to these requirements.
Notwithstanding the provisions of the EMC Directive, the following sub clauses shall be applied for
spectrum management:
transmitter spurious emissions, subclause 4.7
receiver spurious radiations, subclause 5.9
The EMC tests carried out on the basis of article 10.5 of the EMC Directive 89/336/EEC by the notified
bodies established in other Member States would not normally be repeated for licensing purposes in the
United Kingdom.
Applicants who wish to demonstrate compliance with the EMC directive are advised to refer to the RA
Information sheets ‘RA 200: Electromagnetic Compatibility for Radio’ and ‘RA 227 (Rev. 1): EMC - The
EC Type Examination Route to compliance for Radiocommunication Transmission Apparatus’. These are
available on a single copy basis free from the RA Information & Library Service.
It may be necessary for amendments to this specification to be issued. Amendment sheets will be
available from the RA Information and Library Service.
For the latest information concerning Type Approval Status and Licensing conditions, refer to the RA
Information Sheet ‘RA 275: Status of Land Mobile Radio Specifications (MPT 1300 series)’. This
publication also contains contact names and telephone numbers for Agency staff who are able to assist
you with licensing and technical enquiries and is available on a single copy basis free from the RA
Information & Library Service.
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MPT 1314:1997
This revision was required in order to allow for;
a)
This document to be updated in line with the Agency’s current Standard format and layout for the
MPT 1300 series specifications.
b)
To allow for the introduction of equipment operating on 12.5 kHz channel spacing.
The Radiocommunications Agency has a ‘web site’ which can be accessed on
http://www.open.gov.uk/radiocom ;it is planned that all of the MPT 1300 series of specifications will be
available here using ‘LIBRARY’ and ‘MPT Specifications’ options.
Radiocommunications Agency
Information & Library Service
New King's Beam House
22 Upper Ground
London
SE1 9SA
Tel:
0171 211 0502/0505
Fax:
0171 211 0507
E-Mail
library.ra@gtnet.gov.uk
For further information on all radio matters please contact the Agency’s 24 Hour Telephone Service:
0171 211 0211
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MPT 1314:1997
1
1.1
GENERAL
Scope of specification
This specification covers the minimum performance requirements for angle modulated equipment for use in
the PMR Local Communication Service. The equipment comprises the UHF base station transmitter and the
associated portable receivers, also the portable VHF transmitters and the associated base station receiver.
For the equipment covered by this specification, the nominal channel spacing between adjacent carrier
frequencies is 12.5 kHz or 25 kHz.
The specification does not include all characteristics which may be required by the user nor does it represent
the maximum performance achievable.
The MPT 1314 applies to equipment with an external antenna and to equipment with an integral antenna.
In this specification, an integral antenna is defined as one which is designed to be connected permanently to
the transmitter or receiver without the use of an external feeder.
In the case of equipment which is intended for use with either an integral antenna or an external antenna, the
equipment shall be measured as equipment intended for use with an external antenna and shall meet the
appropriate limits. In addition to this,
the transmitter characteristics:
transmitter carrier power,
spurious emissions
and the receiver characteristic:
spurious radiations
shall be measured as for equipment for use with an integral antenna and the appropriate limits shall be met.
1.2
Licensee's responsibility
The use of this equipment is subject to the issue of a licence by the Secretary of State. Under the conditions
of the licence it will be the responsibility of the licensee to ensure that the equipment provided conforms with
and is maintained to the requirements of this specification.
1.3
Operating frequencies
The equipment shall provide for transmission and reception of angle modulated emissions on one or more
carrier frequencies in the bands allocated to the Private Mobile Radio Service. The precise operating
frequencies will be quoted by the Secretary of State when the licence is issued. For the purposes of type
testing, single channel equipment may be submitted operating on any channel in one of the allocated
frequency bands.
NOTE: transmission shall be inhibited until the frequency has stabilised within the required limits.
1.4
Selective signalling
The equipment shall be fitted with:
either a continuous tone controlled signalling system (CTCSS) preferably in accordance with the
standards laid down in the Code of Practice MPT 1306,
or sequential tone signalling preferably in accordance with the standards laid down in the Code of
Practice MPT 1316,
or binary signalling preferably conforming with the requirements of the Code of Practice MPT 1317.
The requirements for equipment employing selective signalling only are given in clause 6.
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MPT 1314:1997
1.5
Auxiliary test equipment
The encoder for the selective signalling system, although itself not subject to type approval, should
accompany the model submitted and include instructions for setting up the correct modulation of the
associated transmitter. This will be used for generating certain test signals.
1.6
Auxiliary information
Complete details of all codes and of the code format should be provided. This information will be recorded by
the testing authority to assist in its monitoring function but will be considered as commercially confidential.
1.7
Construction
Transmitters and receivers may be individual units or combination units but must include their power sources
or supply units.
Alternatively, an independent power supply may be used provided that the manufacturer of the independent
power supply verifies that it shall provide the nominal supply voltage for which the radio equipment is
designed.
1.8
Labelling
The equipment shall be provided with a clear indication of the type number and description under which it is
submitted for type testing.
Each type number shall be unique and in the event that the testing authority finds two manufacturers have
used a similar type number, one manufacturer will be asked to change the type number.
1.9
Controls
Those controls which if maladjusted might increase the interfering potentialities of the equipment shall not be
accessible to the user.
The power adjustment control, if fitted, shall not be accessible to the user.
1.10
Declarations by the manufacturer
When submitting an equipment for type testing, the manufacturer shall supply the following information.
-
Transmitter
Nominal frequency
Oscillator frequency and carrier generation formula
Single channel or multi-channel
Radio frequency switching range
Radio frequency output power
Continuous or intermittent rating
-
Receiver
-
Nominal frequency
Oscillator frequency and local oscillator generation formula
Single channel or multi-channel
Radio frequency switching range
Rated audio frequency output power
Value of resistive load into which audio output is delivered
Power supply
Nominal supply voltage
Type of battery (where applicable)
Battery end point voltage (where applicable)
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MPT 1314:1997
1.11
Classes of emission
Angle modulation shall be used which may be frequency or phase modulation by speech or tones provided
that the requirements of subclause 4.4 are met.
1.12
Synthesisers and PLL systems
Where use is made of a synthesiser and/or a PPL (phase locked loop) system for determining the transmitter
frequency, the transmitter shall be inhibited when synchronisation is absent. Transient behaviour of
transmitters shall be verified with the method of measurement given in subclause 4.9.
2
2.1
TEST CONDITIONS, POWER SOURCES AND AMBIENT TEMPERATURES
Normal and extreme test conditions
Type tests shall be made under normal test conditions and also, where stated, under extreme test conditions.
2.2
Test power source
During type tests the power source of the equipment shall be replaced by a test power source capable of
producing normal and extreme test voltages as specified in subclauses 2.3.2 and 2.4.2. The internal
impedance of the test power source shall be low enough for its effect on the test results to be negligible. For
the purpose of tests, the voltage of the power source shall be measured at the input terminals of the
equipment.
If the equipment is provided with a permanently connected power cable, the test voltage shall be that
measured at the point of connection of the power cable to the equipment.
For battery operated equipment, the batteries shall be removed and the test power source shall be applied as
close to the battery terminals as practicable.
During tests the power source voltages shall be maintained within a tolerance of < ± 1 % relative to the
voltage at the beginning of each test. The value of this tolerance is critical to power measurements, using a
smaller tolerance will provide better measurement uncertainty values.
2.3
2.3.1
Normal test conditions
Normal temperature and humidity
The normal temperature and humidity conditions for the tests shall be any convenient combination of
temperature and humidity within the following ranges:
temperature
relative humidity:
+ 15°C to + 35°C;
20 % to 75 %.
When it is impracticable to carry out the tests under these conditions, the ambient temperature and relative
humidity during the tests shall be stated in the test report.
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MPT 1314:1997
2.3.2
Normal test power source
2.3.2.1
Mains voltage
The normal test voltage for equipment to be connected to the mains shall be the nominal mains voltage. For
the purpose of this specification, the nominal voltage shall be the declared voltage or any of the declared
voltages for which the equipment was designed.
The frequency of the test power source, corresponding to the AC mains, shall be between 49 and 51 Hz.
2.3.2.2
Regulated lead-acid battery power sources used on vehicles
When the radio equipment is intended for operation from the usual types of regulated lead-acid battery power
source used on vehicles, the normal test voltage shall be 1.1 x the nominal voltage of the battery (6 V, 12 V
etc.).
2.3.2.3
Other power sources
For operation from other power sources or types of battery (primary or secondary), the normal test voltage
shall be that declared by the equipment manufacturer.
2.4
Extreme test conditions
2.4.1
Extreme temperatures
For tests at extreme temperatures, measurements shall be made, in accordance with the procedures
specified in subclause 2.5, at the upper temperature of + 55°C and at the lower temperature of - 10°C.
2.4.2
Extreme test source voltages
2.4.2.1
Mains voltage
The extreme test voltage for equipment to be connected to an AC mains source shall be the nominal mains
voltage ± 10 %.
2.4.2.2
Regulated lead-acid battery power sources used on vehicles
When the equipment is intended for operation from the usual types of regulated lead-acid battery power
sources used on vehicles, the extreme test voltages shall be 1.3 and 0.9 x the nominal voltage of the battery
(6 V, 12 V, etc.).
2.4.2.3
Power sources using other types of batteries
The lower extreme test voltages for equipment with power sources using the following batteries shall be:
for the Leclanché or the lithium type of battery: 0.85 x the nominal voltage of the battery;
for the mercury or nickel-cadmium type of battery: 0.9 x the nominal voltage of the battery.
No upper extreme test voltages apply.
2.4.2.4
Other power sources
For equipment using other power sources, the extreme test voltages shall be those agreed between the
equipment manufacturer and the testing authority and shall be recorded in the test report.
2.4.2.5
Variety of power sources
For equipment capable of operation from a variety of power sources, the extreme test voltages shall
correspond to those of the sources referred to in subclauses 2.4.2.1, 2.4.2.2 and 2.4.2.3, if appropriate.
2.5
Procedure for tests at extreme temperatures
Before measurements are made the equipment shall have reached thermal balance in the test chamber. The
equipment shall be switched off during the temperature stabilising period.
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MPT 1314:1997
In the case of equipment containing temperature stabilisation circuits designed to operate continuously, the
temperature stabilisation circuits may be switched on for 15 minutes after thermal balance has been
obtained, and the equipment shall then meet the specified requirements. For such equipment the
manufacturer shall provide for the power source circuit feeding the crystal oven to be independent of the
power source to the rest of the equipment.
If the thermal balance is not checked by measurements, a temperature stabilising period of at least one hour,
or such period as may be decided by the testing authority, shall be allowed. The sequence of measurements
shall be chosen, and the humidity content in the test chamber shall be controlled so that excessive
condensation does not occur.
2.5.1
Procedure for equipment designed for continuous operation
If the manufacturer states that the equipment is designed for continuous operation, the test procedure shall
be as follows:
Before tests at the upper extreme temperature the equipment shall be placed in the test chamber
and left until thermal balance is attained. The equipment shall then be switched on in the transmit
conditions for a period of half an hour after which the equipment shall meet the specified
requirements.
For tests at the lower extreme temperature the equipment shall be left in the test chamber unit
thermal balance is attained, then switched to the standby or receive conditions for a period of one
minute after which the equipment shall meet the specified requirements.
2.5.2
Procedure for equipment designed for intermittent operation
If the manufacturer states that the equipment is designed for intermittent operation, the test procedure shall
be as follows:
Before tests at the upper extreme temperature the equipment shall be placed in the test chamber
and left until thermal balance is attained. The equipment shall then be switched on for one minute in
the transmit condition, followed by four minutes in the receive condition, after which the equipment
shall meet the specified requirements.
For tests at the lower extreme temperature the equipment shall be left in the test chamber until
thermal balance is attained, then switched to the standby or receive condition for one minute after
which the equipment shall meet the specified requirements.
3
3.1
3.1.1
ELECTRICAL TEST CONDITIONS
Normal test modulation
Equipment employing speech modulation
Where stated, for the normal test modulation the modulation frequency shall be 1 kHz and the resulting
frequency deviation shall be 60 % of the maximum permissible frequency deviation, subclause 4.4.1. The
test signal shall be substantially free from amplitude modulation.
3.1.2
Equipment employing selective signalling only
Where stated, the normal test modulation shall be the normal coded test signal specified in subclause 6.5.
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MPT 1314:1997
3.2
Artificial antenna
Where applicable, tests shall be carried out using an artificial antenna which shall be a substantially nonreactive non-radiating load of 50  connected to the antenna connector. The voltage standing wave ratio
(VSWR) at the 50  connector shall not be greater than 1.2 over the frequency range of the measurement.
Tests on the transmitter requiring the use of the test fixture shall be carried out with a substantially nonreactive non-radiating load of 50  connected to the test fixture terminal.
3.3
Transmitter automatic shut-off facility.
If the equipment is fitted with an automatic transmitter shut-off facility, it shall be made inoperative for the
duration of the type test. The operation of the equipment shall not exceed the manufacturers stated duty
cycle.
3.4
Arrangement for test signals at the input of the transmitter
For the purpose of this specification, the transmitter audio frequency modulation signal shall be applied to the
microphone input terminals with the internal microphone disconnected, unless otherwise stated.
3.5
Arrangements for test signals at the input of the receiver
Test signal sources which are applied to the receiver shall present an impedance of 50  to the receiver
input. This requirement shall be met irrespective whether one or more signals using a combining network are
applied to the receiver simultaneously.
The levels of the test signals shall be expressed in terms of the e.m.f. at the receiver input connector.
The effects of any intermodulation products and noise produced in the test signal sources shall be negligible.
3.6
Arrangements for test signals at the input of the receiver via a test fixture or a test
antenna
Sources of test signals for application to the receiver via a test fixture (subclause 3.15), a stripline
arrangement (subclause 3.10.4) or a test antenna (subclause 3.13) shall be connected in such a way that the
impedance presented to the test fixture, the stripline or the test antenna is 50 ohms. This requirement shall
be met irrespective whether one or more signals using a combining network are applied to the receiver
simultaneously.
The levels of the test signals shall be expressed in terms of the e.m.f. at the output of the source prior to
connection to the receiver input connector.
The effects of any intermodulation products and noise produced in the test signal sources shall be negligible.
3.7
Receiver mute or squelch facility
If the receiver is equipped with a mute or squelch circuit, this shall be made inoperative for the duration of the
type tests.
3.8
Receiver rated audio output power
The rated audio output power shall be the maximum power, declared by the manufacturer, for which all the
requirements of this standard are met. With normal test modulation, subclause 3.1, the audio output power
shall be measured in a resistive load simulating the load with which the receiver normally operates. The value
of this load shall be declared by the manufacturer.
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MPT 1314:1997
3.9
Test of equipment with a duplex filter
If the equipment is provided with a built-in duplex filter or a separate associated duplex filter, the
requirements of this specification shall be met when the measurements are carried out using the antenna
connector of this filter.
3.10
Test sites and general arrangements for measurements involving the use of radiated
fields
Any of the four test sites described in subclauses 3.10.1 to 3.10.4 may be used.
3.10.1
Open air test site
3.10.1.1
Description
The term "open air" must be understood from a electromagnetic point of view. Such a test site may be in the
open air or alternatively with walls and ceiling transparent to the radio waves at the frequencies considered.
An open air test site can be used to perform the measurements using the radiated measurement methods
described in clauses 4 and 5. Absolute or relative measurements can be performed on transmitters or on
receivers; absolute measurements of field strength require a calibration of the test site.
The open air test site shall be on a reasonably level surface or ground. At one point on the site, a ground
plane of at least 5 m diameter shall be provided. In the middle of this ground plane, a non-conducting support
capable of rotation through 360° in the horizontal plane, shall be used to support the test sample at 1.5 m
above the ground plane. The test site shall be large enough to allow the erection of a measuring or
transmitting antenna at a distance of a half wavelength or 3 m whichever is the greater. The distance actually
used shall be recorded with the results of the tests carried out on the site.
Sufficient precautions shall be taken to ensure that reflections from extraneous objects adjacent to the site
and ground reflections do not degrade the measurements results, in particular:
no extraneous conducting objects having any dimension in excess of a quarter wavelength of the
highest frequency tested shall be in the immediate vicinity of the site,
all cables shall be as short as possible, as much of the cables as possible shall be on the ground
plane or preferably below and the low impedance cables shall be screened.
2
Specified
height
range
1 to 4 m
1
1.5 m
Ground plane
4
1
2
3
4
3
Equipment under test
Test antenna
High pass filter (necessary for strong fundamental Tx radiation)
Spectrum analyser or selective voltmeter
3.10.1.2
Figure 1: Measuring arrangement
Establishment of a relationship between signal levels and field strength
Page 17
MPT 1314:1997
This procedure allows the creation, in a given place, of a known field strength by the means of a signal
generator connected to a test antenna. It is valid only at a given frequency for a given polarisation and for the
exact position of the test antenna.
3
Specified
height
range
1 to 4 m
2
1.5 m
Ground plane
1
1
2
3
4
4
Selective voltmeter
Substitution antenna
Test antenna
Signal generator
Figure 2:
Measuring arrangement
All the equipment shall be adjusted to the frequency used.
The test antenna and the substitution antenna shall have the same polarisation.
The substitution antenna connected to the selective voltmeter constitutes a calibrated field strength meter.
a)
The signal generator level shall be adjusted to produce the required field strength as measured on
the selective voltmeter.
b)
The test antenna shall be raised or lowered through the specified range until the maximum signal
level is detected on the selective voltmeter.
c)
The signal generator level shall be readjusted to produce the required field strength as measured
on the selective voltmeter thus to establish a relationship between the signal generator level and the
field strength.
3.10.2
3.10.2.1
Indoor test site
Description
An indoor test site is a partly screened site, where the wall located behind the test sample is covered with a
radio frequency absorbing material and a corner reflector is used with the test antenna.
The site may be used when the frequency of the signals being measured is greater than 80 MHz.
The measurement site may be a laboratory room with a minimum area of 6 m by 7 m and at least 2.7 m in
height.
Apart from the measuring apparatus and the operator, the room shall be as free as possible from
reflecting objects other than the walls, floor and ceiling.
The potential reflections from the wall behind the equipment under test are reduced by placing a barrier of
absorbent material in front of it. The corner reflector around the test antenna is used to reduce the effect
of reflections from the opposite wall and from the floor and ceiling in the case of horizontally polarised
measurements. Similarly, the corner reflector reduces the effects of reflections from the side walls for
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MPT 1314:1997
vertically polarised measurements. For the lower part of the frequency range (below approximately
175 MHz) no corner reflector or absorbent barrier is needed. For practical reasons, the half wavelength
antenna in figure 3 may be replaced by an antenna of constant length, provided that this length is between
a quarter wavelength and one wavelength at the frequency of measurement and the sensitivity of the
measuring system is sufficient. In the same way the distance of half wavelength to the apex may be
varied.
Ceiling
1,35 m
Absorbing material
Feeder to
test receiver
or signal
generator
Corner reflector
Reference
point of
test sample
/2 Test antenna
Wall

/2
m
0,75 m
0,6 m
1,35 m
Floor
Figure 3:
3.10.2.2
Indoor test site arrangement (shown for horizontal polarisation)
Test for parasitic reflections
To ensure that errors are not caused by the propagation path approaching the point at which phase
cancellation between direct and the remaining reflected signals occurs, the substitution antenna shall be
moved through a distance of ± 0.1 m in the direction of the test antenna as well as in the two directions
perpendicular to this first direction.
If these changes of distance cause a signal change of greater than 2 dB, the test sample should be
repositioned until a change of less than 2 dB is obtained.
3.10.2.3
Mode of use
The mode of use is the same as for an open air test site, the only difference being that the test antenna does
not need to be raised and lowered whilst searching for a maximum, which simplifies the method of
measurement.
3.10.3
3.10.3.1
Anechoic chamber
General
An anechoic chamber is a well shielded chamber covered inside with radio frequency absorbing material and
simulating a free space environment. It is an alternative site on which to perform the measurements using the
radiated measurement methods described in clauses 4 and 5. Absolute or relative measurements can be
performed on transmitters or on receivers. Absolute measurements of field strength require a calibration of
the anechoic chamber. The test antenna, equipment under test and substitution antenna are used in a way
similar to that at the open air test site, but are all located at the same fixed height above the floor.
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MPT 1314:1997
3.10.3.2
Description
An anechoic chamber should meet the requirements for shielding loss and wall return loss as shown in figure
4. Figure 5 shows an example of the construction of an anechoic chamber having a base area of 5 m by
10 m and a height of 5 m. The ceiling and walls are coated with pyramidally formed absorbers approximately
1 m high. The base is covered with special absorbers which form the floor. The available internal dimensions
of the chamber are 3 m x 8 m x 3 m, so that a maximum measuring distance of 5 m in the middle axis of this
chamber is available (see Bibliography {4}, subclause 3.16). The floor absorbers reject floor reflections so
that the antenna height need not be changed. Anechoic chambers of other dimensions may be used.
At 100 MHz the measuring distance can be extended up to a maximum of two wavelengths.
3.10.3.3
Influence of parasitic reflections
For free-space propagation in the far field the relationship of the field strength X and the distance R is given
by X = Xo x (Ro/R), where Xo is the reference field strength and Ro is the reference distance. This relationship
allows relative measurements to be made as all constants are eliminated within the ratio and neither cable
attenuation nor antenna mismatch or antenna dimensions are of importance.
If the logarithm of the foregoing equation is used, the deviation from the ideal curve can be easily seen
because the ideal correlation of field strength and distance appears as a straight line. The deviations
occurring in practice are then clearly visible. This indirect method shows quickly and easily any disturbances
due to reflections and is far less difficult than the direct measurement of reflection attenuation.
With an anechoic chamber of the dimensions given in the foregoing, at frequencies below 100 MHz there are
no far field conditions, but the wall reflections are stronger, so that careful calibration is necessary. In the
frequency range from 100 MHz to 1 GHz the dependence of the field strength on the distance meets the
expectations very well. Above 1 GHz, because more reflections will occur, the dependence of the field
strength on the distance will not correlate so closely.
3.10.3.4
Mode of use
The mode of use is the same as for an open air test site, the only difference being that the test antenna does
not need to be raised and lowered whilst searching for a maximum signal level, which simplifies the method
of measurement.
a (dB)
110
100
90
80
70
Minimum limit for the sheilding loss
60
50
40
30
20
10
0
Limit of the return loss
10 k
100 k
Figure 4:
1M
10 M
30 M 100 M 300 M 1 G
Specification for shielding and reflections
4G
10 G f (Hz)
Page 20
MPT 1314:1997
10 m
Equipment
under test
Measurement distance
Measuring
Antenna
5m
Non-conductive turntables
Non-conductive surface
1m
Ground plan
Measurement distance
5m
Non-conductive turntables
Absorbers
Filter blocks and
coaxial feedthrough
Figure 5:
3.10.4
3.10.4.1
Shielded room without
absorbers for the
test instruments
Anechoic shielded chamber for simulated free space measurements
Stripline arrangement
General
The stripline arrangement is a RF coupling device for coupling the integral antenna of an equipment to a 50
 radio frequency terminal. This allows the radiated measurements to be performed without an open air test
site but in a restricted frequency range. Absolute or relative measurements can be performed; absolute
measurements require a calibration of the stripline arrangement.
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MPT 1314:1997
3.10.4.2
Description
The stripline is made of three highly conductive sheets forming part of a transmission line which allows the
equipment under test to be placed within a known electric field. The stripline must be sufficiently rigid to
support the equipment under test.
Two examples of stripline characteristics are as follows.
Useful frequency range
Equipment size limits
(antenna included):
3.10.4.3
IEC 489-3 App.J {2}
FTZ No512 TB 9 {3}
1 to 200
200
200
250
0.1 to 4000
1200
1200
400
MHz
length, mm
width, mm
height, mm
Calibration
The aim of calibration is to establish at any frequency a relationship between the voltage applied by the
signal generator and the field strength at the designated test area inside the stripline.
3.10.4.4
Mode of use
The stripline arrangement may be used for all radiated measurements within its calibrated frequency range.
The method of measurement is the same as the method using an open air test site with the following
change. The stripline arrangement input socket is used instead of the test antenna.
3.11
Standard position
The standard position in all test sites, except in the stripline arrangement, for equipment which is not intended
to be worn on a person, including hand-held equipment, shall be on a non-conducting support, height 1.5 m,
capable of rotating about a vertical axis through the equipment. The standard position of the equipment shall
be as follows:
a)
For equipment with an integral antenna, the equipment shall be placed in the position closest to
normal use as declared by the manufacturer.
b)
For equipment with a rigid external antenna, the antenna shall be vertical.
c)
For equipment with a non-rigid external antenna, the antenna shall be extended vertically upwards
by a non-conducting support.
Equipment which is intended to be worn on a person may be tested using a simulated man as support.
The simulated man comprises a rotatable acrylic tube filled with salt water, placed on the ground.
The dimensions of the container shall be as follows:
Height
Inside diameter
Sidewall thickness
1.7 m ± 0.1 m
300 mm ± 5 mm
5 mm ± 0.5 mm
The container shall be filled with a salt (NaCl) solution of 1.5 g per litre of distilled water.
The equipment shall be fixed to the surface of the simulated man, at the appropriate height for the
equipment.
NOTE: To reduce the weight of the simulated man it may be possible to use an alternative tube which has a
hollow centre of 220 mm maximum diameter.
In the stripline arrangement the equipment under test or the substitution antenna is placed in the designated
test area in the normal operational position, relative to the applied field, on a pedestal made of a low dielectric
material (dielectric constant less than 2).
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MPT 1314:1997
3.12
3.12.1
Acoustic coupler
General
When radiation measurements are performed on the receiver, the audio output voltage should be conducted
from the receiver to the measuring equipment without perturbing the field near the receiver.
This perturbation can be minimised by using wires with high resistivity associated to a test equipment with a
high input impedance (IEC 489-3 Appendix F {1}).
When this situation is not applicable, an acoustic coupler shall be used.
NOTE: When using this acoustic coupler care should be exercised that possible ambient noise does not
influence the test result.
3.12.2
Description
The acoustic coupler comprises a plastic funnel, an acoustic pipe and a microphone with a suitable amplifier.
The acoustic pipe shall be long enough (e.g. 2 m) to reach from the equipment under test to the
microphone which is located in a position that will not disturb the RF field. The acoustic pipe shall
have an inner diameter of about 6 mm and a wall thickness of about 1.5 mm and should be
sufficiently flexible to allow the platform to rotate.
The plastic funnel shall have a diameter appropriate to the size of the loudspeaker in the equipment
under test, with soft foam rubber glued to its edge, it shall be fitted to one end of the acoustic pipe
and the microphone shall be fitted to the other end. It is very important to fix the
centre of the
funnel in a reproducible position relative to the equipment under test, since the position of the centre
has a strong influence on the frequency response that will be measured. This can be achieved by
placing the equipment in a close fitting acoustic mounting jig, supplied by the manufacturer, of
which the funnel is an integral part.
The microphone shall have a response characteristic flat within 1 dB over a frequency range of
50 Hz to 20 kHz, a linear dynamic range of at least 50 dB. The sensitivity of the microphone and the
receiver audio output level shall be suitable to measure a signal to noise ratio of at least 40 dB at
the nominal audio output level of the equipment under test. Its size should be sufficiently small to
couple to the acoustic pipe.
The frequency correcting network shall correct the frequency response of the acoustic coupler so
that the acoustic SINAD measurement is valid, IEC 489-3 Appendix F {1}.
3.12.3
Calibration
The aim of the calibration of the acoustic coupler is to determine the acoustic SINAD ratio which is equivalent
to the SINAD ratio at the receiver output.
Rx
under
test
Signal
generator
Test fixture
acoustic
Micro
phone
Amplifier and
filter
pipe
1
2
SINAD
meter
Figure 6:
Measuring arrangement for calibration
Page 23
MPT 1314:1997
a)
The acoustic coupler shall be mounted to the equipment, if necessary using a test fixture. A direct
electrical connection to the terminals of the output transducer will be made. A signal generator shall
be connected to the receiver input (or to the test fixture input). The signal generator shall be at the
nominal frequency of the receiver and shall be modulated by the normal test modulation.
b)
Where possible, the receiver volume control shall be adjusted to give at least 50 % of the rated
audio output power and, in the case of stepped volume controls, to the first step that provides an
output power of at least 50 % of the rated audio output power.
c)
The test signal input level shall be reduced until an electrical SINAD ratio of 20 dB is obtained, the
connection being in position 1. The signal input level shall be recorded.
d)
With the same signal input level, the acoustic equivalent SINAD ratio shall be measured and
recorded, the connection being in position 2.
e)
Steps c) and d) shall be repeated for an electrical SINAD ratio of 14 dB and the acoustic equivalent
SINAD ratio measured and recorded.
3.13
Test antenna
When the test site is used for radiation measurements the test antenna is used to detect the field from both
the test sample and the substitution antenna. When the test site is used for the measurement of receiver
characteristics the antenna is used as a transmitting antenna. This antenna is mounted on a support capable
of allowing the antenna to be used in either horizontal or vertical polarisation and for the height of its centre
above the ground to be varied over the range 1 m to 4 m. Preferably test antennas with pronounced
directivity should be used. The size of the test antenna along the measurement axis shall not exceed 20 % of
the measuring distance.
3.14
Substitution antenna
The substitution antenna is used to replace the equipment under test. For measurements below 1 GHz the
substitution antenna shall be a half wavelength dipole resonant at the frequency under consideration, or a
shortened dipole, calibrated to the half wavelength dipole. For measurements between 1 GHz and 4 GHz
either a half wavelength dipole or a horn radiator may be used. The centre of this antenna shall coincide with
the reference point of the test sample it has replaced. This reference point shall be the volume centre of the
sample when its antenna is mounted inside the cabinet, or the point where an outside antenna is connected
to the cabinet.
The distance between the lower extremity of the dipole and the ground shall be at least 0.3 m.
NOTE: The gain of a horn antenna is generally expressed relative to an isotropic radiator.
Page 24
MPT 1314:1997
3.15
Test fixture
3.15.1
Description
The test fixture is a radio frequency coupling device associated with an integral antenna equipment for
coupling the integral antenna to a 50  radio frequency terminal at the working frequencies of the equipment
under test. This allows certain measurements to be performed using the conducted measurement methods.
Only relative measurements may be performed and only those at or near frequencies for which the test
fixture has been calibrated.
The test fixture shall provide:
a connection to an external power supply and
an audio interface either by direct connection or by an acoustic coupler.
The test fixture normally shall be provided by the manufacturer.
The performance characteristics of the test fixture shall be approved by the testing authority and shall
conform with the requirements a) to f) which are as follows.
a)
The coupling loss shall not be greater than 30 dB.
b)
A coupling loss variation over the frequency range used in the measurement shall not exceed 2 dB.
c)
Circuits associated with the RF coupling shall contain no active or non linear devices.
d)
The VSWR at the 50  terminal shall not be greater than 1.5 over the frequency range of the
measurements.
e)
The coupling loss shall be independent of the position of the test fixture and be unaffected by the
proximity of surrounding objects or people. The coupling loss shall be reproducible when the
equipment under test is removed and replaced.
f)
The coupling loss shall remain substantially constant when the environmental conditions are varied.
The characteristics shall be included in the test report.
3.15.2
Calibration
The calibration of the test fixture establishes a relationship between the output of the signal generator and the
field strength applied to the equipment inside the test fixture.
The calibration is valid only at a given frequency and for a given polarisation of the reference field.
Receiver
under test
Signal
generator
1
2
Test fixture
1
2
AF load/acoustic coupler
Distortion factor/audio level meter and psophometric filter
Figure 7:
a)
Measuring arrangement for calibration
Using the method described in subclause 5.2, measure the sensitivity expressed as field strength
and note the value of this field strength in dBV/m and the polarisation used.
Page 25
MPT 1314:1997
b)
The receiver is now placed in the test fixture which is connected to the signal generator. The level
of the signal generator producing a SINAD of 20 dB shall be noted.
c)
The calibration of the test fixture is thus the linear relationship between the field strength in dBV/m
and the signal generator level in dBV emf.
3.15.3
Mode of use
The test fixture may be used to facilitate some of the measurements in clauses 4 and 5 on equipment with an
integral antenna.
It is used in the measurements of effective radiated power and of average usable sensitivity in clauses 4 and
5 to enable these measurements to be made under extreme test conditions.
For the transmitter measurements calibration of the test fixture is not required.
For the receiver measurements calibration of the test fixture is necessary.
To apply the specified wanted signal level expressed as field strength, convert the signal into the signal
generator level (emf) using the calibration of the test fixture. Apply this value using the signal generator.
3.16
Bibliography
{1}
IEC Publication 489-3 Second edition (1988) Appendix F pages 130 to 133.
{2}
IEC Publication 489-3 Second edition (1988) Appendix J pages 156 to 164.
{3}
Construction of a Stripline. Technical Report FTZ No 512 TB 9.
{4}
Ketterling, H-P: Verification of the performance of fully and semi-anechoic chambers for radiation
measurements and susceptibility / immunity testing, 1991, Leatherhead / Surrey.
4
4.1
4.1.1
TRANSMITTER
Frequency error
Definition
The frequency error of the transmitter is the difference between the measured carrier frequency in the
absence of modulation and the nominal frequency of the transmitter.
4.1.2
Method of measurement
The carrier frequency shall be measured in the absence of modulation with the transmitter connected to an
artificial antenna, subclause 3.2.
A transmitter without a 50  output connector shall be placed in the test fixture, subclause 3.7, connected to
an artificial antenna.
The measurement shall be made under normal test conditions, subclause 2.3, and repeated under extreme
test conditions, (subclauses 2.4.1 and 2.4.2 applied simultaneously).
Page 26
MPT 1314:1997
4.1.3
Limits
The frequency error under normal, extreme or any intermediate set of conditions shall not exceed the values
defined in table 1.
Table 1:
Frequency error limit
Channel separation
(kHz)
Frequency error limit
(kHz)
12.5 kHz
±1.0 (Fixed)
±1.5 (Mobile)
25.0 kHz
±2.0
For practical reasons the measurements will be performed only under normal and extreme test conditions as
defined in subclause 4.1.2.
4.2
Carrier power (conducted)
The maximum value of the transmitter output power and/or the maximum value of the effective radiated
power of the carrier in an operating system will be a condition of the licence.
If the equipment is designed to operate with different carrier powers, the rated power for each level or range
of levels shall be declared by the manufacturer.
The requirements of this specification shall be met for all power levels at which the transmitter is intended to
operate. For practical reasons measurements shall be performed only at the lowest and the highest power
level at which the transmitter is intended to operate.
4.2.1
Definitions
The transmitter carrier power (conducted, normal conditions) is the mean power delivered to the artificial
antenna during a radio frequency cycle in the absence of modulation.
The rated output power is the carrier power (conducted) of the equipment declared by the manufacturer. Its
value shall be declared under normal test conditions.
4.2.2
Method of measurement
The transmitter shall be connected to an artificial antenna, subclause 3.2, and the power delivered to this
artificial antenna shall be measured.
The measurements shall be made under normal test conditions, subclause 2.3, and extreme test conditions,
subclause s 2.4.1 and 2.4.2 applied simultaneously.
4.2.3
Limits
The carrier power measured under normal test conditions shall be within ± 1.5 dB from the rated carrier
power.
The variation of power due to the change of temperature and voltage for the measurements under extreme
test conditions shall not exceed + 2.0 dB or - 3.0 dB.
4.3
Effective radiated power (field strength)
The maximum value of the effective radiated power of the carrier in an operating system will be a condition of
the licence.
If the equipment is designed to operate with different carrier powers, the rated effective radiated power for
each level or range of levels shall be declared by the manufacturer.
Page 27
MPT 1314:1997
The requirements of this specification shall be met for all power levels at which the transmitter is intended to
operate. For practical reasons measurements shall be performed only at the lowest and the highest power
level at which the transmitter is intended to operate.
4.3.1
Definitions
For the purpose of this measurement, the maximum carrier radiated power is defined as the effective
radiated power in the direction of the maximum field strength under specified conditions of measurement and
in the absence of modulation.
The rated effective radiated power is the effective radiated power of the equipment as declared by the
manufacturer.
The average carrier power is defined as the average of the effective radiated power measured in 8 directions.
The average effective radiated power shall also be declared by the manufacturer.
4.3.2
Methods of measurement
This subclause applies only to equipment without an external antenna connector.
4.3.2.1
Maximum effective radiated power under normal test conditions
test site
1
2
3
1
2
3
Transmitter under test
Test antenna
Spectrum analyser or selective voltmeter
Figure 8:
a)
Measurement arrangement
A test site which fulfils the requirements of the specified frequency range of this measurement shall
be used. The test antenna shall be orientated initially for vertical polarisation unless otherwise
stated.
The transmitter under test shall be placed on the support in its standard position (subclause 3.11)
and switched on without modulation.
b)
The spectrum analyser or selective voltmeter shall be tuned to the transmitter carrier frequency.
The test antenna shall be raised or lowered through the specified height range until the maximum
signal level is detected on the spectrum analyser or selective voltmeter.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3 (i.e. an anechoic chamber).
Page 28
MPT 1314:1997
c)
The transmitter shall be rotated through 360° about a vertical axis until a higher maximum signal is
received.
d)
The test antenna shall be raised or lowered again through the specified height range until a
maximum is obtained. This level shall be recorded. (This maximum may be a lower value than the
value obtainable at heights outside the specified limits). The test antenna need not be raised or
lowered if the measurement is carried out on a test site according to subclause 3.10.3.
test site
2
3
1
1
2
3
4
4
Signal generator
Substitution antenna
Test antenna
Spectrum analyser or selective voltmeter
Figure 9:
e)
Measurement arrangement
Using measurement arrangement shown in figure 9, the substitution antenna, subclause 3.14, shall
replace the transmitter antenna in the same position and in vertical polarisation. The frequency of
the signal generator shall be adjusted to the transmitter carrier frequency. The test antenna shall be
raised or lowered as necessary to ensure that the maximum signal is still received.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3.
The input signal to the substitution antenna shall be adjusted in level until an equal or a known
related level to that detected from the transmitter is obtained in the test receiver.
The maximum carrier radiated power is equal to the power supplied by the signal generator,
increased by the known relationship if necessary and after corrections due to the gain of the
substitution antenna and the cable loss between the signal generator and the substitution antenna.
f)
Steps b) to e) shall be repeated with the test antenna and the substitution antenna orientated in
horizontal polarisation.
4.3.2.2
Average effective radiated power under normal test conditions
a)
The procedures in steps b) to f) in subclause 4.3.2.1 shall be repeated except that in step c) the
transmitter shall be rotated through 8 positions, 45° apart, starting at the position corresponding to
maximum effective radiated power.
b)
The average effective radiated power corresponding to the eight average values is given by the
formula:
Page 29
MPT 1314:1997
1 X
8
8
average power =
where X is the power corresponding to each position.
4.3.3
Method of measurements of maximum and average effective radiated power under
extreme test conditions
Transmitter
under test
Test
load
RF power
meter
Test fixture
Figure 10: Measurement arrangement
a)
The measurement specified in subclause 4.3.2 shall also be performed under extreme test
conditions. Due to the impossibility of repeating this measurement on a test site under extreme
temperature conditions, only a relative measurement is performed using the test fixture, subclause
3.15, and the measurement arrangement shown in figure 10.
b)
The power delivered to the test load is measured under normal and extreme test conditions and the
difference in dB is noted. This difference is algebraically added to the carrier radiated power under
normal test conditions, in order to obtain the carrier radiated power under extreme test conditions.
Additional uncertainties can occur under extreme test conditions due to the calibration of the test
fixture.
4.3.4
Limits
The maximum effective radiated power measured under normal test conditions, subclause 4.3.2.1, shall be
within ± 1.5 dB from the rated maximum effective radiated power.
The average effective radiated power measured under normal test conditions, subclause 4.3.2.2, shall be
within ± 1.5 dB from the rated average effective radiated power.
The variation of power due to the change of temperature and voltage for the measurements under extreme
test conditions, subclause 4.3.3, shall not exceed + 2.0 dB or - 3.0 dB.
4.4
Frequency deviation
The frequency deviation is the maximum difference between the instantaneous frequency of the frequency or
phase modulated radio frequency signal and the carrier frequency in the absence of modulation.
4.4.1
Maximum permissible frequency deviation
4.4.1.1
Definition
The maximum permissible frequency deviation is the maximum value of frequency deviation stated for the
relevant channel separation.
4.4.1.2
Method of measurement
The transmitter shall be connected to the artificial antenna, subclause 3.2.
Page 30
MPT 1314:1997
Equipment with an integral antenna shall be placed in a test fixture, subclause 3.15, connected to the artificial
antenna.
The frequency deviation shall be measured by means of a deviation meter capable of measuring the
maximum permissible frequency deviation, including that due to any harmonics and intermodulation products
which may be produced in the transmitter. The deviation meter bandwidth must be suitable to accommodate
the highest modulating frequency and to achieve the required dynamic range.
4.4.1.2.1
Analogue signals within the audio bandwidth
a)
The modulation frequency shall be varied between the lowest frequency considered to be
appropriate and 2.55 kHz for 12.5 kHz channel spaced equipment and 3.0 kHz for other cases. The
level of this test signal shall be 20 dB above the level of the normal test modulation, subclause
3.1.1.
b)
The maximum (positive or negative) frequency deviation shall be recorded.
4.4.1.2.2
Analogue signals above the audio bandwidth
a)
The modulation frequency shall be varied between 2.55 kHz/3.0 kHz and a frequency equal to the
channel separation for which the equipment is intended. The level of this signal shall be the level of
the normal test signal, subclause 3.1.1.
b)
The maximum (positive or negative) frequency deviation shall be recorded.
4.4.1.3
Limits
The maximum permissible frequency deviation modulation at any modulation frequency shall not exceed
2.5 kHz or 5 kHz (12.5 kHz or 25 kHz channel spaced equipment respectively).
The frequency deviation at modulation frequencies between 2.55 kHz/3.0 kHz shall not exceed the frequency
deviation at a modulation frequency of 2.55 kHz/3.0 kHz. At 6.0 kHz the deviation shall be not more than ±
1.5 kHz.
The frequency deviation at modulation frequencies between 6.0 kHz and 25.0 kHz shall not exceed that
given by a linear representation of the frequency deviation (dB) relative to the modulation frequency starting
at the 6.0 kHz limit and having a slope of - 14 dB per octave.
4.5
4.5.1
Adjacent channel power
Definition
The adjacent channel power is that part of the total output power of a transmitter, under defined conditions of
modulation, which falls within a specified passband centred on the nominal frequency of either of the
adjacent channels.
This power is the sum of the mean power produced by the modulation, hum and noise of the transmitter.
4.5.2
Method of measurement
The adjacent channel power shall be measured with a power measuring receiver which conforms with the
requirements given in subclause 4.6, referred to in this subclause as the "receiver".
a)
The transmitter shall be operated at the carrier power determined in subclause 4.2 under normal
test conditions, subclause 2.3.
In the case of equipment with integral antenna the equipment shall be placed in a test fixture,
subclause 3.15, and operated at the effective radiated power determined in subclause 4.3.2.1 under
normal test conditions. When using a test fixture, it is important to ensure that direct radiation from
the transmitter to the "receiver" does not affect the result.
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MPT 1314:1997
The output of the transmitter shall be connected to the input of the "receiver" by a 50  power
attenuator, to ensure that the impedance presented to the transmitter is 50  and that the level at
the "receiver" input is appropriate.
b)
With the transmitter unmodulated, the tuning of the "receiver" shall be adjusted so that a maximum
response is obtained. This is the 0 dB reference point. The "receiver" variable attenuator setting and
the reading of the rms value indicator shall be recorded.
c)
The frequency of the "receiver" shall be adjusted above the carrier so that the "receiver" - 6 dB
response nearest to the transmitter carrier frequency is located at a displacement of 8.25 kHz or
17.0 kHz (for 12.5 kHz or 25 kHz channel spaced equipment respectively) from the nominal carrier
frequency.
d)
The transmitter shall be modulated by a test signal of 1 250 Hz at a level which is 20 dB higher than
that required to produce the normal test modulation, subclause 3.1.1.
e)
The "receiver" variable attenuator shall be adjusted to obtain the same reading as in step b) or a
known relation to it.
f)
The ratio of adjacent channel power to carrier power is the difference between the attenuator
settings in steps b) and e), corrected for any differences in the reading of the rms value indicator.
g)
The measurement shall be repeated with the frequency of the "receiver" adjusted below the carrier
so that the "receiver" - 6 dB response nearest to the transmitter carrier frequency is located at a
displacement of 8.25 kHz or 17.0 kHz (12.5 kHz or 25 kHz channel spaced equipment respectively)
from the nominal carrier frequency.
4.5.3
Limit
The adjacent channel power shall not exceed a value of 55.0 dB in the case of 12.5 kHz channel spaced
equipment and 70.0 dB in other cases below the transmitter carrier power without the need to be below
0.20 µW.
4.6
4.6.1
Power measuring receiver specification
General
The power measuring receiver consists of a mixer and oscillator, an IF filter, an amplifier, a variable
attenuator and a level indicator as shown in figure 11.
Input
Mixer
Filter
Amplifier
and
attenuator
Level
indicator
Oscillator
Figure 11: Power measuring receiver
The technical characteristics of the power measuring receiver are given in subclauses 4.6.2 to 4.6.5.
4.6.2
IF filter
The IF filter shall be within the limits of the selectivity characteristic of figure 12.
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MPT 1314:1997
The selectivity characteristics shall keep the frequency separations and tolerances given in tables 3 and 4.
The minimum attenuation of the filter outside the 90 dB attenuation points must be equal to or be greater
than 90 dB.
NOTE: A symmetrical filter can be used provided that each side meets the tighter tolerances and the D2
points have been calibrated relative to the - 6 dB response. When a non-symmetrical filter is used the
receiver must be designed in such a way that the tighter tolerance is used close to the carrier.
dB
D4
D4
90
close
to
carrier
D3
D3
26
D2
D2
6
2
D1
distant
from
carrier
D1
0
kHz
Figure 12: Selectivity characteristic
The selectivity characteristic shall keep the frequency separations from the nominal centre frequency of the
adjacent channel specified in table 2.
Table 2:
Channel
Separation (kHz)
Selectivity characteristic
Frequency separation of filter curve from nominal centre frequency of
adjacent channel (kHz)
D1
D2
D3
D4
12.5 kHz
3.00
4.25
5.50
9.50
25.0 kHz
5.55
8.00
9.25
13.25
The attenuation points shall not exceed the tolerances specified in tables 3 and 4.
Table 3:
Attenuation points close to carrier
Channel
separation (kHz)
Tolerance range
(kHz)
D1
D2
D3
D4
12.5 kHz
+1.35
±0.10
-1.35
-5.35
25.0 kHz
±3.10
±0.10
-1.35
-5.35
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MPT 1314:1997
Table 4:
Attenuation points distant from the carrier
Channel
separation (kHz)
Tolerance range (kHz)
D1
D2
D3
D4
12.5 kHz
±2.00
±2.00
±2.00
+2.0/-60
25.0 kHz
±3.50
±3.50
±3.50
+3.5/-7.5
The minimum attenuation of the filter outside the 90 dB attenuation points shall be greater than or equal to 90
dB.
Table 5:
Frequency displacement
Channel Separation
(kHz)
Specified necessary
bandwidth (kHz)
Displacement from - 6.0 dB
points (kHz)
12.5 kHz
8.5
8.25
25.0 kHz
16.0
17.0
The tuning of the power measuring receiver shall be adjusted away from the carrier so that the - 6 dB
response nearest to the transmitter carrier frequency is located at a displacement from the nominal carrier
frequency as specified in table 5.
4.6.3
Oscillator and amplifier
The measurement of the reference frequencies and the setting of the local oscillator frequency shall be within
± 50 Hz.
The mixer, oscillator and the amplifier shall be designed in such a way that the measurement of the adjacent
channel power of an unmodulated test signal source, whose noise has a negligible influence on the
measurement result, yields a measured value of -90 dB referred to the level of the test signal source.
The linearity of the amplifier shall be such that an error in the reading of no more than 1.5 dB will be obtained
over an input level variation of 100 dB.
4.6.4
Attenuation indicator
The attenuation indicator shall have a minimum range of 80 dB and a resolution of 1 dB.
4.6.5
Level indicators
Two level indicators are required to cover the rms and the peak transient measurements.
4.6.5.1
Rms level indicator
The rms level indicator shall indicate accurately non-sinusoidal signals within a ratio of 10:1 between peak
value and rms value.
4.6.5.2
Peak level indicator
The peak level indicator shall indicate accurately and store the peak power level. A storage oscilloscope or a
spectrum analyser may be used as a peak level indicator.
4.7
4.7.1
Spurious emissions
Definition
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MPT 1314:1997
Spurious emissions are emissions at frequencies other than those of the carrier and sidebands associated
with normal test modulation. The level of spurious emissions shall be measured
either as:
the power level in a specified load (conducted spurious emission) and
the effective radiated power when radiated by the cabinet and structure of the equipment (cabinet
radiation),
or as:
the effective radiated power when radiated by the cabinet and the integral antenna, in the case of
equipment fitted with such an antenna and no external antenna connector.
4.7.2
Method of measuring the power level in a specified load
This method applies only to equipment with an external antenna connector.
a)
The transmitter shall be connected to a 50  power attenuator. The output of the power attenuator
shall be connected to a measuring receiver, subclause 4.6.
b)
The transmitter shall be switched on without modulation, and the measuring receiver, subclause
4.6, shall be tuned over the frequency range 100 kHz to 4 GHz.
At each frequency at which a spurious component is detected, the power level shall be recorded as
the conducted spurious emission level delivered into the specified load, except for the channel on
which the transmitter is intended to operate and the adjacent channels.
c)
The measurements shall be repeated with the transmitter on standby.
4.7.3
Methods of measuring the effective radiated power
4.7.3.1
Equipment with an external antenna connector
This method applies only to equipment with an external antenna connector.
a)
On a test site conforming with the requirements of subclause 3.10, the equipment shall be placed at
the specified height on a non-conducting support and in the position closest to normal use as
declared by the manufacturer.
The transmitter antenna connector shall be connected to an artificial antenna, subclause 3.2.
b)
The test antenna shall be orientated for vertical polarisation and the length of the test antenna shall
be chosen to correspond to the instantaneous frequency of the measuring receiver. The output of
the test antenna shall be connected to a measuring receiver, subclause 4.6.
c)
The transmitter shall be switched on (without modulation) and the measuring receiver shall be
tuned over the frequency range 25 MHz to 4 GHz, except for the channel on which the transmitter is
intended to operate and its adjacent channels.
At each frequency at which a spurious component is detected, the test antenna shall be raised and
lowered through the specified range of heights until a maximum signal level is detected on the
measuring receiver.
The maximum signal level detected by the measuring receiver shall be noted.
d)
The transmitter shall be replaced by a substitution antenna as defined in subclause 3.14. The
substitution antenna shall be orientated for vertical polarisation and the length of the substitution
antenna shall be adjusted to correspond to the frequency of the spurious component detected.
The substitution antenna shall be connected to a calibrated signal generator. The frequency of the
calibrated signal generator shall be set to the frequency of the spurious component detected.
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MPT 1314:1997
The input attenuator setting of the measuring receiver shall be adjusted in order to increase the
sensitivity of the measuring receiver, if necessary.
The test antenna shall be raised and lowered through the specified range of heights to ensure that
the maximum signal is received.
The input signal to the substitution antenna shall be adjusted so that it produces a level detected by
the measuring receiver which is equal to the level noted while the spurious component was
measured, corrected for the change of input attenuator setting of the measuring receiver.
The input level to the substitution antenna shall be recorded as power level, corrected for the
change of input attenuator setting of the measuring receiver.
e)
The measurement shall be repeated with the test antenna and the substitution antenna orientated
for horizontal polarisation.
f)
The measure of the effective radiated power of the spurious components is the larger of the two
power levels recorded for each spurious component at the input to the substitution antenna,
corrected for the gain of the antenna if necessary.
g)
The measurements shall be repeated with the transmitter on standby.
4.7.3.2
Equipment without an external antenna connector
This method applies only to equipment without an external antenna connector.
test site
1
2
3
1
2
3
4
4
Transmitter under test
Test antenna
High 'Q' (notch) or high pass filter
Spectrum analyser or selective voltmeter
Figure 13: Measurement arrangement
a)
A test site which fulfils the requirements of the specified frequency range of this measurement shall
be used.
The test antenna shall be orientated initially for vertical polarisation and connected to a spectrum
analyser, or a selective voltmeter, through a suitable filter to avoid overloading of the spectrum
analyser or selective voltmeter. The bandwidth of the spectrum analyser or selective voltmeter shall
be between 10 kHz and 100 kHz, set to a suitable value to perform the measurement correctly.
For the measurement of spurious emissions below the second harmonic of the carrier frequency
the filter used shall be a high 'Q' (notch) filter centred on the transmitter carrier frequency and
attenuating this signal by at least 30 dB.
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MPT 1314:1997
For the measurement of spurious emissions at and above the second harmonic of the carrier
frequency the filter used shall be a high pass filter with a stop band rejection exceeding 40 dB. The
cut-off frequency of the high pass filter shall be approximately 1.5 times the transmitter carrier
frequency.
The transmitter under test shall be placed on the support in its standard position (subclause 3.11)
and shall be switched on without modulation.
b)
The radiation of any spurious emission shall be detected by the test antenna and spectrum analyser
or selective voltmeter over the frequency range 25 MHz to 4 GHz, except for the channel on which
the transmitter is intended to operate and its adjacent channels.
The frequency of each spurious emission detected shall be recorded.
If the test site is disturbed by interference coming from outside, this qualitative search may be
performed in a screened room, with a reduced distance between the transmitter and the test
antenna.
c)
At each frequency at which an emission has been detected, the spectrum analyser or selective
voltmeter shall be tuned and the test antenna shall be raised or lowered through the specified
height range until the maximum signal level is detected on the spectrum analyser or selective
voltmeter.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3 (i.e. an anechoic chamber).
d)
The transmitter shall be rotated through 360° about a vertical axis, until the highest maximum signal
is received.
e)
The test antenna shall be raised or lowered again through the specified height range until a
maximum is obtained. This level shall be recorded.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3.
test site
2
3
1
1
2
3
4
4
Signal generator
Substitution antenna
Test antenna
Spectrum analyser or selective voltmeter
Figure 14: Measurement arrangement
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MPT 1314:1997
f)
Using measurement arrangement shown in figure 14, the substitution antenna shall replace the
transmitter antenna in the same position and in vertical polarisation. It shall be connected to the
signal generator.
g)
At each frequency at which an emission has been detected, the signal generator, substitution
antenna and spectrum analyser or selective voltmeter shall be tuned. The test antenna shall be
raised or lowered through the specified height range until the maximum signal level is detected on
the spectrum analyser or selective voltmeter.
The test antenna need not be raised or lowered if the measurement is carried out on a test site in
according to subclause 3.10.3.
The level of the signal generator giving the same signal level on the spectrum analyser or selective
voltmeter as in step e) shall be recorded. This value, after corrections due to the gain of the
substitution antenna and the cable loss between the signal generator and the substitution antenna,
is the radiated spurious emission at this frequency.
The resolution bandwidth of the measuring instrument shall be the smallest bandwidth available
which is greater than the spectral width of the spurious component being measured.
h)
Steps c) to g) shall be repeated with the test antenna orientated in horizontal polarisation.
i)
Steps c) to h) shall be repeated with the transmitter in standby condition if this option is available.
4.7.4
Limits
The power of any spurious emission shall not exceed the values given in tables 6 and 7.
Table 6:
Frequency range
100 kHz to 1 GHz
>1 GHz to 4 GHz
Tx operating
0.25 µW
1.00 µW
Tx standby
2.0 nW
20.0 nW
Table 7:
4.8
Conducted spurious emissions
Radiated spurious emissions
Frequency range
25 MHz to 1 GHz
>1 GHz to 4 GHz
Tx operating
0.25 µW
1.00 µW
Tx standby
2.0 nW
20.0 nW
Intermodulation attenuation
This requirement applies only to transmitters to be used in base stations at fixed locations.
4.8.1
Definition
Intermodulation attenuation is the capability of a transmitter to avoid the generation of signals in the
non-linear elements caused by the presence of the carrier and an interfering signal entering the transmitter
via the antenna.
It is specified as the ratio, in dB, of the carrier power level to the power level of the third order intermodulation
product.
4.8.2
Method of measurement
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MPT 1314:1997
Trasmitter
under test
Directional
coupler
50  10 dB
Spectrum
analyser
50  20 dB
Interfering
test signal
source
50  terminator
50  attenuator
Figure 15: Measurement arrangement
The measurement arrangement shown in figure 15 shall be used.
The transmitter shall be connected to a 50  10 dB power attenuator and via a directional coupler to a
spectrum analyser. An additional attenuator may be required between the directional coupler and the
spectrum analyser to avoid overloading the spectrum analyser.
In order to reduce the influence of mismatch errors it is important that the 10 dB power attenuator is coupled
to the transmitter under test with the shortest possible connection.
The interfering test signal source is connected to the other end of the directional coupler via a 50  20 dB
power attenuator.
The interfering signal source may be either a transmitter providing the same power output as the transmitter
under test and be of a similar type, or a signal generator and a linear power amplifier capable of delivering
the same output power as the transmitter under test.
The directional coupler shall have an insertion loss of less than 1 dB, a sufficient bandwidth and a directivity
of more than 20 dB.
The transmitter under test and the test signal source shall be physically separated in such a way that the
measurement is not influenced by direct radiation.
The transmitter under test shall be unmodulated and the spectrum analyser adjusted to give a maximum
indication with a frequency scan width of 500 kHz.
The interfering test signal source shall be unmodulated and the frequency shall be 1 to 4 neighbouring
channels above the frequency of the transmitter under test.
The frequency shall be chosen in such a way that the intermodulation components to be measured do not
coincide with other spurious components.
The power output of the interfering test signal source shall be adjusted to the carrier power level of the
transmitter under test by the use of a power meter.
The intermodulation component shall be measured by direct observation on the spectrum analyser and the
ratio of the largest third order intermodulation component to the carrier shall be recorded.
This measurement shall be repeated with the interfering test signal source at a frequency within 1 to 4
neighbouring channels below the frequency of the transmitter under test.
4.8.3
Limits
Two classes of transmitter intermodulation attenuation are defined, the equipment shall fulfil one of the
requirements as follows:
The intermodulation attenuation ratio shall be at least 40.0 dB for any intermodulation component.
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MPT 1314:1997
For base stations to be used in special service conditions (e.g. at sites where more than one
transmitter will be in service), or when the regulatory authority makes it a condition of the licence,
the intermodulation attenuation ratio shall be at least 70.0 dB for any intermodulation component.
In the case where the performance is achieved by additional internal or external isolating devices
(such as circulators) these shall be supplied at the time of type testing and shall be used for the
measurements.
4.9
Transient frequency behaviour of the transmitter
This measurement does not apply to equipment designed for continuous operation only.
4.9.1
Definitions
The transient frequency behaviour of the transmitter is the variation in time of the frequency error of the
transmitter from the time when the radio frequency output power is switched on and off.
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MPT 1314:1997
The relevant instants and periods are defined as follows:
ton:
The switch-on instant at which the output power of the transmitter, measured at the antenna
terminal, exceeds 0.1 % of the nominal power.
t1:
The transient period starting at ton and of specified duration depending on the nominal frequency of
the transmitter, table 7 in subclause 4.9.3 refers.
t2:
The transient period starting at the end of t1 and of specified duration depending on the nominal
frequency of the transmitter, table 7 in subclause 4.9.3 refers.
toff:
The switch-off instant at which the output power of the transmitter, measured at the antenna
terminal, falls below 0.1 % of the nominal power.
t3:
The transient period finishing at toff and of specified duration depending on the nominal frequency of
the transmitter, table 7 in subclause 4.9.3 refers.
4.9.2
Method of measurement
Transmitter
under test
(ad)
50  power
attenuator
Combining
network
Test
discriminator
(fd)
Storage
oscilloscope
Signal generator
Figure 16: Measurement arrangement
The measurement arrangement shown in figure 16 shall be used.
Two signals shall be connected to the test discriminator via a combining network.
The transmitter shall be connected to a 50  power attenuator.
The output of the power attenuator shall be connected to the test discriminator, subclause 4.9.4, via one input
of the combining network. A test signal generator shall be connected to the second input of the combining
network.
The test signal shall be adjusted to the nominal frequency of the transmitter. The test signal shall be
modulated by a frequency of 1 kHz with a deviation equal to ± the value of the relevant channel separation.
The test signal level shall be adjusted to correspond to 0.1 % of the power of the transmitter under test
measured at the input of the test discriminator. This level shall be maintained throughout the measurement.
The amplitude difference (ad) and the frequency difference (fd) output of the test discriminator shall be
connected to a storage oscilloscope. The storage oscilloscope shall be set to display the channel
corresponding to the (fd) input of up to ± 1 channel frequency difference, pertaining to the relevant channel
separation from the nominal frequency of the transmitter.
The storage oscilloscope shall be set to a sweep rate of 10 ms/division and set so that the triggering occurs
at 1 division from the left edge of the display. The display will show the 1 kHz test signal continuously.
The storage oscilloscope shall then be set to trigger on the channel corresponding to the amplitude
difference (ad), that is the level of 0.1 % of the power of the tested transmitter for a rising input level.
The transmitter shall then be switched on, without modulation, to produce the trigger pulse and a picture on
the display.
The result of the change in the ratio of power between the test signal and the transmitter output will, due to
the capture ratio of the test discriminator, produce two separate sides on the picture, one showing the 1 kHz
test signal, the other the frequency difference of the transmitter versus time.
The moment when the 1 kHz test signal is completely suppressed is considered to provide the instant ton.
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MPT 1314:1997
The periods t1 and t2 as specified in table 7, subclause 4.9.3, shall be used to define the appropriate
template.
During the periods t1 and t2 the frequency difference shall not exceed the values specified in subclause
4.9.3.
The frequency difference, after the end of the period t2, shall be within the limit of the frequency error,
subclause 4.1.3.
The result shall be recorded as frequency difference versus time.
The transmitter shall remain switched on.
The storage oscilloscope shall be set to trigger on the channel corresponding to the amplitude difference (ad)
input at a high input level, decaying and set so that the triggering occurs at one division from the right edge of
the display.
The transmitter shall then be switched off.
The moment when the 1 kHz test signal starts to rise is considered to provide the instant toff.
The period t3 specified in table 7, subclause 4.9.3, shall be used to define the appropriate template.
During the period t3 the frequency difference shall not exceed the values specified in subclause 4.9.3.
Before the start of the period t3, the frequency difference shall be within the limit of the frequency error,
subclause 4.1.3.
The result shall be recorded as frequency difference versus time.
If an unmodulated carrier cannot be obtained, then the measurements shall be made with the transmitter
modulated by the normal test signal, see subclause 3.1, and an extra half of the channel separation will be
accepted for the limit of the peak frequency difference.
4.9.3
Limits
The transient periods are specified in table 8.
The transient periods for the frequency range 300 MHz to 500 MHz are shown as an example in figure 17.
Table 8:
Frequency range (MHz)
Transient periods
30 to 300
>300 to 500
5.0
10.0
t2
20.0
25.0
t3
5.0
10.0
Period (ms)
t1
During the periods t1 and t3 the frequency difference shall not exceed the value of one channel separation.
During the period t2 the frequency difference shall not exceed the value of half a channel separation.
In the case of equipment from which an unmodulated carrier cannot be obtained, an extra half a channel
separation will be accepted for the limit of the peak frequency difference.
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MPT 1314:1997
Switch on condition ton, t1 and t2
+f=1 channel
separation
+f=½ channel
separation
- nominal
frequency
-f=½ channel
separation
ms
10
ton
20
t1
30
40
50
60
70
80
-f=1 channel
separation
100
90
t2
Switch off condition t3, toff
+f=1 channel
separation
+f=½ channel
separation
- nominal
frequency
-f=½ channel
separation
ms
10
20
30
40
50
60
70
80
-f=1 channel
separation
100
90
t3
toff
Figure 17: Storage oscilloscope view of t1, t2 and t3
Page 43
MPT 1314:1997
4.9.4
Test discriminator
The test discriminator consists of a mixer and a local oscillator (auxiliary frequency) to convert the transmitter
frequency to be measured into the frequency of a broadband limiter amplifier and of a broadband
discriminator whose principal characteristics are as follows.
The test discriminator shall be sensitive and accurate enough to cope with transmitter carrier
powers as low as 0.1 mW.
The test discriminator must be fast enough to display the frequency deviations (approximately
100 kHz/100 s).
The test discriminator output must be d.c. coupled.
5
5.1
5.1.1
RECEIVER
Maximum usable sensitivity (conducted)
Definition
The maximum usable sensitivity (conducted) of the receiver is the minimum level of signal (e.m.f.) at the
receiver input, at the nominal frequency of the receiver and with normal test modulation, subclause 3.1, which
will produce:
an audio frequency output power of at least 50 % of the rated power output, subclause 3.8, and
a SINAD ratio of 20 dB, measured at the receiver output through a telephone psophometric
weighting network as described in CCITT Recommendation 0.41 Red Book 1984.
5.1.2
Method of measurement
This method applies only to equipment with an external antenna connector.
The test signal, at the nominal frequency of the receiver, with normal test modulation, subclause 3.1, at an
e.m.f. of 6.0 dBV, the value of the limit for the maximum usable sensitivity, shall be applied to the receiver
input connector.
An audio frequency output load, a SINAD meter and a psophometric telephone weighting network,
mentioned in subclause 5.1.1, shall be connected to the receiver output terminals.
Where possible, the receiver volume control shall be adjusted to give at least 50% of the rated output power,
subclause 3.8, or, in the case of stepped volume controls, to the first step that provides an output power of at
least 50% of the rated output power.
The test signal input level shall be reduced until a SINAD ratio of 20 dB is obtained.
The test signal input level under these conditions is the value of the maximum usable sensitivity.
The measurement shall be made under normal test conditions, subclause 2.3, and repeated under extreme
test conditions, subclauses 2.4.1 and 2.4.2 applied simultaneously.
Under extreme test conditions, the receiver audio output power shall be within ± 3.0 dB of the value obtained
under normal test condition.
5.1.3
Limits
The maximum usable sensitivity shall not exceed an e.m.f. of 6.0 dBV under normal test conditions and an
e.m.f. of 12.0 dBV under extreme test conditions.
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MPT 1314:1997
5.2
Average usable sensitivity expressed as a field strength
5.2.1
Definition
The average measured usable sensitivity expressed as field strength is the average of eight measurements
of field strength, in dBV/m, at the nominal frequency of the receiver and with specified test modulation which
produce a SINAD ratio of 20 dB measured at the receiver output through a psophometric weighting network,
mentioned in subclause 5.1.1, when the receiver is rotated in 45° increments starting at a particular
orientation.
NOTE: The average usable sensitivity mostly differs only by a small amount from the maximum usable
sensitivity to be found in a particular direction. This is due to the properties of the averaging process used in
the formula in subclause 5.2.2 g). For instance, an error not exceeding 1.2 dB can be found if the sensitivity
is equal in seven directions and is extremely bad in the eighth direction. For the same reason the starting
direction (or angle) can be selected randomly.
5.2.2
Method of measurement under normal test conditions
This method applies only to equipment without an external antenna connector.
A test site which fulfils the requirements of the specified frequency range of this measurement shall be used.
The test antenna shall be orientated for vertical polarisation or for the polarisation in which the equipment
under test is intended to operate.
test site
3
1
1
2
3
4
5
4
5
2
SINAD meter and psophometric weighting network.
AF load/acoustic coupler
Receiver under test
Test antenna
Signal generator
Figure 18: Measurement arrangement
a)
b)
A signal generator shall be connected to the test antenna. The signal generator shall be at the
nominal frequency of the receiver and shall be modulated by the normal test modulation, subclause
3.1. The receiver under test shall be placed on the support in its standard position, subclause 3.11,
in a random orientation. A distortion factor meter incorporating a 1 000 Hz band-stop filter (or a
SINAD meter) shall be connected to the receiver output terminals via a psophometric filter and an
audio frequency load or by an acoustic coupler for receivers not fitted with a direct connection
(subclause 3.12).
The output level of the signal generator shall be adjusted until a psophometrically weighted SINAD
ratio (or its acoustic equivalent) of 20 dB is obtained.
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MPT 1314:1997
c)
The test antenna shall be raised or lowered through the specified height range to find the lowest
level of the test signal that produces a psophometrically weighted SINAD ratio (or its acoustic
equivalent) of 20 dB.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3 (i.e. an anechoic chamber).
d)
Note the minimum signal generator level from step b) or c) as appropriate.
e)
Steps b) to d) shall be repeated for the remaining seven positions 45° apart of the receiver and the
corresponding values of the generator output which produces the psophometrically weighted SINAD
ratio of 20 dB again (or its acoustic equivalent) shall be determined and noted.
f)
Using the relationship in subclause 3.10.1.2, calculate and record the eight field strengths Xi in
mV/m corresponding to the foregoing output levels of the signal generator.
g)
The average sensitivity expressed as field strength Emean (dBV/m) is given by the formula:
Emean = 20 log
8

i 8
i 1
1
x i2
where Xi represents each of the eight field strengths calculated in step f).
The recorded result is the average usable sensitivity expressed in dBµV/m.
h)
The reference direction shall be that at which the maximum sensitivity level (i.e. the minimum field
strength for 20 dB SINAD noted during the measurement) occurred in the eight measuring
positions.
The corresponding direction, height (where applicable) and this reference field strength value shall
be recorded.
5.2.3
Method of measurement under extreme test conditions
Using the test fixture in measurement arrangement shown in figure 19, the measurement shall be performed
also under extreme test conditions.
Signal
generator
Receiver
under test
AF load/
acoustic
coupler
Psophometric
weighting
network and
SINAD meter
Test fixture
Figure 19: Measurement arrangement
The test signal input level providing a psophometrically weighted SINAD ratio of 20 dB (or its acoustic
equivalent) shall be determined under normal and under extreme test conditions and the difference in dB
shall be calculated. This difference shall be added to the average measured usable sensitivity to radiated
fields expressed in dBV/m, as calculated in subclause 5.2.2 paragraph g), under normal test conditions, to
obtain the sensitivity under extreme test conditions.
5.2.4
Limits
The maximum value of the average usable sensitivity shall not exceed a field strength of 26.0 dBµV/m under
normal test conditions and 32.0 dBµV/m under extreme test conditions.
5.2.5
Degradation measurements
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MPT 1314:1997
5.2.5.1
Definition
Degradation measurements are those measurements which are made on the receiver to establish the
degradation of the SINAD ratio at the output of the receiver from a wanted signal by an unwanted signal or
signals.
Degradation measurements are in two categories:
those carried out on a test site (subclauses 5.6, 5.8 and 3.10),
those carried out using a test fixture (subclauses 5.4, 5.5, 5.7 and 3.15).
The test fixture is only used for those tests where the difference in frequency of the wanted and unwanted
test signals is very small in relation to the actual frequency, so that the coupling loss is the same for the
wanted and unwanted test signals fed into the test fixture.
5.2.5.2
Procedures
As the test fixture is coupled to the signal generators via a combining network to provide the wanted and
unwanted test input signals to the receiver in the test fixture, it is necessary to establish the test output level
of the wanted test signal from the signal generator that results in a signal at the receiver input when it is in the
test fixture which corresponds to the average usable radiated sensitivity as specified in subclause 5.2.4.
This test output level from the signal generator for the wanted test signal is then used for all the receiver
measurements using the test fixture.
The method for determining the test output level from the signal generator is as follows.
a)
The average usable sensitivity of the receiver is measured in accordance with subclause 5.2.2 g)
and expressed as a radiated field strength which produces a 20 dB SINAD ratio at the output of the
receiver using a psophometric filter.
b)
The difference between the measured average usable sensitivity and the maximum average usable
sensitivity specified in subclause 5.2.4, expressed in dB, is noted.
c)
The receiver is then mounted in the test fixture. The signal generator providing the wanted input
signal is coupled to the test fixture via a combining network. All other input ports of the combining
network are terminated in 50  loads. The output from the signal generator with the normal test
modulation, subclause 3.1, is adjusted so that a SINAD ratio of 20 dB is obtained at the receiver
output (with a psophometric filter). This output is then increased by an amount corresponding to the
difference, expressed in dB, which is noted in step b).
The output level of the signal generator and the SINAD value (or S/N) are noted. The test output
level from the signal generator providing the wanted input test signal for all receiver degradation
measurements using the test fixture is the level corresponding to the noted SINAD value (or S/N).
This is subsequently referred to as the level of the signal generator A which provides the wanted
signal at a level equivalent to the limit of the average usable sensitivity expressed as a field
strength, subclause 5.2.4.
d)
When measurements are carried out on a test site, the wanted and unwanted signals shall be
calibrated in terms of dBµV/m at the position of the equipment under test.
For measurements according to subclauses 5.6, 5.8 and 3.10, the height of the test antenna and
the direction (angle) of the equipment under test shall be that recorded in subclause 5.2.2 h
(reference direction).
5.3
5.3.1
Amplitude characteristic of the receiver
Definition
The amplitude characteristic of the receiver is the relationship between the radio frequency input level of a
specified modulated signal and the audio frequency level at the receiver output.
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MPT 1314:1997
5.3.2
a)
Method of measurement
For the equipment with an external antenna connector, a test signal at the nominal frequency of the
receiver, with normal test modulation, subclause 3.1, and at an e.m.f. equal the value of the limit for
the maximum usable sensitivity, subclause 5.1.3, shall be applied to the receiver input connector.
The equipment without an external antenna connector shall be placed in the test fixture, subclause
3.15. A test signal at the nominal frequency of the receiver, with normal test modulation, subclause
3.1, and at a level equivalent to the maximum value of the average usable sensitivity expressed as
a field strength, subclause 5.2.4, shall be applied to the input of the test fixture.
b)
The audio output level shall be adjusted to approximately 25% of the rated output power, subclause
3.8. In case of a stepped volume control, the control shall be set to the first step which provides an
output power of at least 25 % of the rated output power. The audio output level shall be recorded.
c)
For the equipment with an external antenna connector, the input signal shall be increased to an
e.m.f. of 100.0 dBV and the level of the audio output shall be measured and recorded. For the
equipment without an external antenna connector, the input signal shall be increased by 70.0 dB
and the level of the audio output shall be measured and recorded.
d)
The amplitude characteristic of the receiver is recorded as the change in the level of the audio
output measured in steps b) and c) expressed in dB.
5.3.3
Limit
Within the specified change in the radio frequency input signal level, the change of the audio output level
shall not exceed 3.0 dB between the maximum and minimum radio frequency input signal levels.
5.4
5.4.1
Co-channel rejection
Definition
The co-channel rejection for analogue speech is the capability of the receiver to receive a wanted modulated
signal at the nominal frequency without exceeding a given degradation due to the presence of an unwanted
modulated signal also at the nominal frequency of the receiver.
It is specified as the ratio in decibels of the level of the unwanted signal to the specified wanted signal level at
the receiver input which produces through a psophometric weighting network a SINAD ratio of 14 dB.
5.4.2
a)
Method of measurement
For the equipment with an external antenna connector, two signal generators A and B shall be
connected to the receiver via a combining network, subclause 3.5.
The equipment without an external antenna connector shall be placed in the test fixture, subclause
3.15. Two signal generators shall be connected to the receiver input via a combining network,
subclause 3.6, and the test fixture.
The wanted test signal, represented by the signal generator A connected to one input of the
combining network, shall be at the nominal frequency of the receiver and shall have normal test
modulation, subclause 3.1.
The unwanted test signal, represented by the signal generator B connected to the second input of
the combining network, shall be at the nominal frequency of the receiver and shall be modulated
with a frequency of 400 Hz at a deviation of 60% of the maximum permissible frequency deviation,
subclause 4.4.1.
b)
Initially the unwanted signal shall be switched off (maintaining its output impedance). The amplitude
of the signal generator A shall be adjusted to a level which:
for equipment with an external antenna connector is equal to the value of the limit for the
maximum usable sensitivity, subclause 5.1.3,
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MPT 1314:1997
for equipment without an external antenna connector is equivalent to the maximum value of
the average usable sensitivity expressed as a field strength, subclause 5.2.4.
c)
The unwanted signal shall then be switched on and its level shall be adjusted so that the unwanted
signal causes:
a reduction of 3 dB in the audio output level of the wanted signal, or
a reduction to 14 dB of the SINAD ratio at the receiver output (with a psophometric filter),
whether or not measured acoustically,
whichever occurs first.
d)
The co-channel rejection shall be recorded as the ratio in dB of the level of the unwanted test signal
to the level of the wanted test signal at the receiver input for which the specified reduction in SINAD
ratio occurs. This ratio is the same as the ratio of the outputs of the two signal generators.
This ratio shall be noted.
e)
The measurement shall be repeated for displacements of the unwanted test signal of ± 1 500 Hz
and ± 3 000 Hz.
f)
The lowest value of the five measurement results noted shall be recorded as the co-channel
rejection.
5.4.3
Limit
The value of the co-channel rejection ratio at any frequency of the unwanted signal within the specified range
shall be between - 8.0 dB and 0.0 dB.
5.5
5.5.1
Adjacent channel selectivity
Definition
The adjacent channel selectivity is a measure of the capability of the receiver to receive a wanted modulated
signal at the nominal frequency without exceeding a given degradation due to the presence of an unwanted
modulated signal which differs in frequency from the wanted signal by an amount equal to the adjacent
channel separation for which the equipment is intended.
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MPT 1314:1997
5.5.2
Equipment with an external antenna connector
5.5.2.1
a)
Method of measurement
Two signal generators A and B shall be connected to the receiver via a combining network,
subclause 3.5.
The wanted test signal, represented by the signal generator A connected to one input of the
combining network, shall be at the nominal frequency of the receiver and shall have normal test
modulation, subclause 3.1.
The unwanted test signal, represented by the signal generator B connected to the second input of
the combining network, shall be at the frequency of the channel immediately above that of the
wanted signal of and shall be modulated with a frequency of 400 Hz at a deviation of 60% of
maximum permissible frequency deviation, subclause 4.4.1.
b)
Initially the unwanted test signal shall be switched off (maintaining its output impedance). The
amplitude of the signal generator A shall be adjusted to obtain at the receiver input an e.m.f. of 6.0
dBµV, the value of the limit for the maximum usable sensitivity, subclause 5.1.3.
c)
The unwanted test signal shall then be switched on and its level shall be adjusted so that the
unwanted signal causes:
a reduction of 3 dB in the audio output level of the wanted signal, or
a reduction to 14 dB of the SINAD ratio at the receiver output (with a psophometric filter),
whether or not measured acoustically,
whichever occurs first. This level shall be noted.
The measure of the adjacent channel selectivity is the ratio in dB of the level of the unwanted signal
to the level of the wanted signal at the receiver input for which the specified reduction in the SINAD
ratio occurs. This ratio shall be recorded.
d)
The measurement shall be repeated with an unwanted test signal at the frequency of the channel
below that of the wanted signal.
e)
The two noted ratios shall be recorded as the upper and lower adjacent channel selectivity.
f)
The measurements shall be repeated under extreme test conditions, subclauses 2.4.1 and 2.4.2
applied simultaneously, with the amplitude of the wanted test signal level adjusted to obtain an
e.m.f. of + 12.0 dBµV at the receiver input.
5.5.2.2
Limits
The adjacent channel selectivity shall be not less than 60.0 dB or 70.0 dB under normal test conditions and
not less than 50.0 dB or 60.0 dB under extreme conditions (for 12.5 kHz or 25 kHz channel spaced
equipment respectively) .
5.5.3
Equipment without an external antenna connector
5.5.3.1
a)
Method of measurement
The equipment shall be placed in the test fixture, subclause 3.15. Two signal generators A and B
shall be connected to the receiver input via a combining network, subclause 3.6, and the test
fixture.
The wanted test signal, represented by the signal generator A connected to one input of the
combining network, shall be at the nominal frequency of the receiver and shall have normal test
modulation, subclause 3.1.
The unwanted test signal, represented by the signal generator B connected to the second input of
the combining network, shall be at the frequency of the channel immediately above that of the
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MPT 1314:1997
wanted signal of and shall be modulated with a frequency of 400 Hz at a deviation of 60% of the
maximum permissible frequency deviation, subclause 4.4.1.
b)
Initially the unwanted test signal shall be switched off (maintaining its output impedance). The
amplitude of the signal generator A shall be adjusted to obtain at the receiver input a level
equivalent to 26.0 dBµV/m, the value of the limit for the average usable sensitivity expressed as a
field strength, subclause 5.2.4.
c)
The unwanted test signal shall then be switched on and its level shall be adjusted so that the
unwanted signal causes:
a reduction of 3 dB in the audio output level of the wanted signal, or
a reduction to 14 dB of the SINAD ratio at the receiver output (with a psophometric filter),
whether or not measured acoustically,
whichever occurs first. This level shall be noted.
The level of the unwanted signal, expressed as a field strength in dBµV/m is then calculated by
taking the average usable sensitivity limit, subclause 5.2.4, and adding to that limit the difference in
dB between the output of signal generators B and A. This level shall be recorded.
d)
The measurement shall be repeated with an unwanted signal at the frequency of the channel below
that of the wanted signal.
e)
The adjacent channel selectivity shall be recorded for the upper and lower adjacent channels as the
level of the unwanted signal at the receiver input for which the specified reduction in SINAD takes
place.
f)
The measurements shall be repeated under extreme test conditions, subclauses 2.4.1 and 2.4.2
applied simultaneously, with the amplitude of the wanted test signal level adjusted to obtain a level
equivalent to a field strength of 32.0 dBµV/m at the receiver input.
5.5.3.2
Limits
The adjacent channel selectivity shall be:
not less than (20 log10f + 38.3) dBµV/m under normal test conditions
and not less than (20 log10f + 28.3) dBµV/m under extreme test conditions,
where f is the frequency in MHz.
5.6
Spurious response rejection
Spurious responses may occur at all frequencies throughout the frequency spectrum and the requirements of
this specification shall be met for all frequencies. For practical reasons the measurements for type testing
shall be performed as specified in subclauses 5.6.1 to 5.6.6. This method of measurement is not intended to
capture all spurious responses but selects those that have a high probability of being present. However, in a
limited frequency range close to the nominal frequency of the receiver, it has been considered impossible to
determine the probability of a spurious response and therefore a search shall be performed over this limited
frequency range. This method provides a high degree of confidence that the equipment also meets the
requirements at frequencies not being measured.
5.6.1
Definition
The spurious response rejection is the capability of the receiver to discriminate between the wanted
modulated radiated field at the nominal frequency and an unwanted radiated field at any other frequency at
which a response is obtained.
5.6.2
Introduction to the method of measurement
To determine the frequencies at which spurious responses can occur calculations as detailed in subclauses
5.6.2.1 and 5.6.2.2 and shall be made as follows.
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MPT 1314:1997
5.6.2.1
Calculation of the limited frequency range
The limited frequency range is equal to the frequency of the local oscillator signal (flo) applied to the 1st mixer
of the receiver plus or minus the sum of the intermediate frequencies (fi1,...fin) and a half the switching range
of the receiver.
Hence the frequency fl of the limited frequency range is
f lo - i=n
i=1 f i -
5.6.2.2
sr
sr
 f l  f lo + i=n
i=1 f i +
2
2
Calculation of frequencies outside the limited frequency range
A calculation of the frequencies at which spurious responses can occur outside the range determined in
5.6.2.1) is made for the remainder of the frequency range of interest, as appropriate, subclause 5.4.5 d.
The frequencies outside the limited frequency range are equal to the harmonics of the frequency of the local
oscillator signal (flo) applied to the 1st mixer of the receiver plus or minus the 1st intermediate frequency (f i1)
of the receiver.
Hence:
the frequencies of these spurious responses are nf lo ± fi1,
where n is an integer greater than or equal to 2.
The measure of the first image response of the receiver shall initially be made to verify the calculation of
spurious response frequencies.
For the calculations 5.6.2.1) and 5.6.2.2) the manufacturer shall state the frequency of the receiver, the
frequency of the local oscillator signal (flo) applied to the 1st mixer of the receiver, the intermediate
frequencies (fi1, fi2 etc.), and the switching range of the receiver.
5.6.3
Equipment with an external antenna connector
5.6.3.1
a)
Method of the search
Two signal generators A and B shall be connected to the receiver via a combining network,
subclause 3.5.
The wanted test signal, represented by signal generator A, shall be at the nominal frequency of the
receiver and shall have normal test modulation, subclause 3.1.
The unwanted test signal, represented by signal generator B, shall be modulated with a frequency
of 400 Hz at the maximum permissible frequency deviation, subclause 4.4.1.
b)
Initially the unwanted test signal shall be switched off and the level of the wanted test signal from
signal generator A shall be adjusted to obtain an e.m.f. of 6.0 dBµV at the receiver input, the limit of
the maximum usable sensitivity, subclause 5.1.3.
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MPT 1314:1997
c)
The unwanted test signal shall then be switched on and its level shall be adjusted to obtain an
e.m.f. of 86.0 dBµV at the receiver input.
The frequency of the unwanted test signal shall be varied incrementally over the "limited frequency
range", subclause 5.6.2.
The incremental steps of the frequency of the unwanted test signal shall be 2.5 kHz or 5.0 kHz (for
12.5 kHz or 25 kHz channel spaced equipment respectively) .
The frequency of any spurious response detected during the search shall be recorded for the use in
measurements in accordance with subclause 5.6.3.2.
5.6.3.2
Method of measurement
At each frequency where a spurious response has been detected, within and outside the limited frequency
range, the measurement shall be performed as follows.
a)
The measurement arrangement is identical to that in subclause 5.6.3.1 a).
The wanted test signal, represented by signal generator A, shall be at the nominal frequency of the
receiver and shall have normal test modulation, subclause 3.1.
The unwanted test signal, represented by signal generator B, shall be modulated with a frequency
of 400 Hz at a deviation of 60% of the maximum permissible frequency deviation, subclause 4.4.1.
b)
Initially the unwanted test signal shall be switched off and the level of the wanted test signal from
signal generator A shall be adjusted to obtain an e.m.f. of 6.0 dBµV at the receiver input, the limit of
the maximum usable sensitivity, subclause 5.1.3.
The unwanted test signal shall then be switched on and its level shall be adjusted to an e.m.f. of
86.0 dBµV at the receiver input.
c)
The measurement shall be performed at all spurious response frequencies found during the search
over the "limited frequency range", subclause 5.6.2, and at frequencies calculated for the remainder
of the spurious response frequencies in the frequency range 100 kHz to 4 GHz.
At each frequency at which a spurious response occurs, the level shall of the unwanted test signal
shall be adjusted until the SINAD ratio, psophometrically weighted, is reduced to 14 dB.
d)
The measure of the spurious response rejection is the ratio in dB of the level of the unwanted test
signal to the level of the wanted test signal at the receiver input for which the specified reduction in
SINAD ratio occurs.
The ratio shall be recorded as the spurious response rejection for each spurious response
obtained.
5.6.3.3
Limit
At any frequency separated from the nominal frequency of the receiver by more than one channel, the
spurious response rejection shall not be less than 70.0 dB.
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MPT 1314:1997
5.6.4
Equipment without an external antenna connector
5.6.4.1
Measurement arrangement
test site
8
3
1
4
6
2
5
7
1
2
3
4
5
6
7
8
Psophometric weighting network and SINAD meter
AF load/acoustic coupler
Receiver under test
Wide band test antenna
Combining network (used only when one antenna is used)
Signal generator A
Signal generator B
Test antenna for the wanted signal (see subclause 5.6.4.1 e)
Figure 20: Measurement arrangement
a)
A test site corresponding to that for the measurement of average usable sensitivity shall be used
(subclause 5.2).
b)
The height of the wide band test antenna and the direction (angle) of the equipment under test shall
be positioned as indicated in subclause 5.2.5.2 d).
c)
During the course of the measurement it may be necessary to radiate high powers in a broad
frequency range and care must be taken to avoid the signals causing interference to existing
services which may be operating in the neighbourhood.
d)
In the presence of a reflective ground plane the height of the wide band test antenna has to be
altered to optimise the reflections from the ground plane. This cannot be done simultaneously for
two different frequencies.
If vertical polarisation is used, the ground floor reflection can be effectively eliminated by the use of
an appropriate monopole located directly on the ground plane (rod antenna).
e)
In case the wide band test antenna does not cover the necessary frequency range, alternatively two
different and suitably coupled antennas may be used.
f)
The receiver under test shall be placed in its standard position and in the reference direction on the
support as indicated in subclause 5.2.5.2 d).
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MPT 1314:1997
5.6.4.2
a)
Method of the search
Two signal generators A and B shall be connected to the wide band test antenna via a combining
network, where appropriate, or alternatively to two different antennas in accordance with subclause
5.6.4.1 e).
The test wanted signal, represented by signal generator A, shall be at the nominal frequency of the
receiver and shall have normal test modulation, subclause 3.1.
The unwanted test signal, represented by signal generator B, shall be modulated with a frequency
of 400 Hz at the maximum permissible frequency deviation, subclause 4.4.1.
b)
Initially the unwanted test signal shall be switched off and the level of the wanted test signal shall be
adjusted to obtain a SINAD ratio of approximately 20 dB.
c)
The unwanted test signal shall then be switched on and its level shall be adjusted to give a field
strength which is at least 10 dB above the limit of the spurious response rejection limit, subclause
5.6.4.4, measured at the receiver input, even when on some types of test sites the level of the
unwanted signal is varying considerably with the frequency due to ground reflections.
The frequency of the unwanted test signal shall be varied in increments of 10 kHz over the limited
frequency range and according to calculations outside of this frequency range, subclause 5.6.2 b.
d)
For any spurious response detected, the antenna shall be raised or lowered until the SINAD ratio is
minimised.
The test antenna need not be raised or lowered if a test site according to subclause 3.10.3 is used,
or if the ground floor reflection can effectively be eliminated as indicated in subclause 5.6.4.1 d.
e)
The frequency of any spurious response detected during the search, and the antenna position and
its height shall be recorded for the use in measurements in accordance with subclause 5.6.4.3.
5.6.4.3
Method of measurement
At each frequency where a spurious response has been detected, within and outside the limited frequency
range, the measurement shall be performed as follows.
a)
The measurement arrangement is identical to that in subclause 5.6.4.2).
The wanted test signal, represented by signal generator A, shall be at the nominal frequency of the
receiver and shall have normal test modulation, subclause 3.1.
The unwanted test signal, represented by signal generator B, shall be modulated with a frequency
of 400 Hz at a deviation of 60% of the maximum permissible frequency deviation, subclause 4.4.1.
b)
Initially the unwanted test signal shall be switched off and the level of the wanted test signal from
signal generator A shall be adjusted to be equivalent to the limit of the average usable sensitivity,
subclause 5.2.4, expressed in field strength when measured at the receiver input.
c)
The unwanted test signal shall then be switched on. Its frequency shall be adjusted around the one
originally applied in order to obtain the minimum SINAD. Its level shall be adjusted until a SINAD
ratio of 14 dB (or its acoustic equivalent) through a psophometric weighting network is obtained.
The equivalent of the level of the unwanted test signal expressed as a field strength in dBµV/m shall
be recorded as the level of the spurious response rejection.
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MPT 1314:1997
d)
The measurement shall be repeated at all spurious response frequencies found during the search
over the limited frequency range, subclause 5.6.2, and at frequencies calculated for the remainder
of the spurious response frequencies in the frequency range from f Rx/3.2 or 30 MHz, whichever is
higher, to 3.2 x fRx, where fRx is the nominal frequency of the receiver, with the antenna position and
height noted in subclause 5.6.4.2 e).
e)
The spurious response rejection to radiated fields shall be expressed, for the frequency
concerned, as the level in dBµV/m of the field strength of the unwanted test signal at the receiver
input.
5.6.4.4
Limits
At any frequency separated from the nominal frequency of the receiver by more than one channel, the
spurious response rejection shall be:
 75.0 dBµV/m for unwanted signal frequencies  68.0 MHz and
 (20 log10f + 38.3) dBµV/m for unwanted signal frequencies > 68.0 MHz, where f is the frequency
in MHz.
5.7
Intermodulation response rejection
5.7.1
Definition
The intermodulation response rejection is the capability of a receiver to receive a wanted modulated signal at
the nominal frequency without exceeding a given degradation due to the presence of two or more unwanted
signals with a specific frequency relationship to the wanted signal frequency.
5.7.2
Equipment with an external antenna connector
5.7.2.1
a)
Method of measurement
Three signal generators A, B and C shall be connected to the receiver via a combining network,
subclause 3.5.
The wanted test signal, represented by the signal generator A connected to one input of the
combining network, shall be at the nominal frequency of the receiver and shall have normal test
modulation, subclause 3.1.
The unwanted test signal, represented by the signal generator B connected to the second input of
the combining network, shall be unmodulated and adjusted to the frequency 2 neighbouring
channels above the nominal frequency of the receiver.
The second unwanted test signal, represented by signal generator C connected to the third input of
the combining network, shall be modulated with a frequency of 400 Hz at a deviation of 60% of
maximum permissible frequency deviation, subclause 4.4.1 and adjusted to the frequency 4
neighbouring channels above the nominal frequency of the receiver.
b)
Initially the unwanted test signals shall be switched off (each maintaining its output impedance). The
amplitude of the signal generator A shall be adjusted to produce at the receiver input an e.m.f. of
6.0 dBµV, the value of the limit for the maximum usable sensitivity, subclause 5.1.3.
c)
The two unwanted test signals shall then be switched on. The amplitude of the two unwanted
signals shall be maintained equal and shall be adjusted until the SINAD ratio, through a
psophometric weighting network, is reduced to 14 dB. The frequency of signal generator B shall be
adjusted to produce the maximum degradation of the SINAD ratio. The level of the two unwanted
test signals shall be readjusted to restore the SINAD ratio of 14 dB.
The measure of the intermodulation response rejection is the ratio in dB of the level of the
unwanted test signals to the level of the wanted test signal at the receiver input for which the
specified reduction in SINAD ratio occurs.
This ratio shall be recorded.
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MPT 1314:1997
d)
The measurement shall be repeated with the unwanted signal from signal generator B at a
frequency 50 kHz above frequency 2 neighbouring channels above the wanted signal and with the
unwanted signal from signal generator C at a frequency 4 neighbouring channels above the wanted
signal.
5.7.2.2
Limit
The intermodulation response rejection shall be not less than 70.0 dB for fixed station equipment and not
less than 65 dB for portable equipment.
5.7.3
Equipment without an external antenna connector
5.7.3.1
a)
Method of measurement
The equipment shall be placed in the test fixture, subclause 3.15. Three signal generators shall be
connected to the receiver input via a combining network, subclause 3.6, and the test fixture.
The wanted test signal, represented by the signal generator A connected to one input of the
combining network, shall be at the nominal frequency of the receiver and shall have normal test
modulation, subclause 3.1.
The unwanted test signal, represented by the signal generator B connected to the second input of
the combining network, shall be unmodulated and adjusted to the frequency 2 neighbouring
channels above the nominal frequency of the receiver.
The second unwanted test signal, represented by signal generator C connected to the third input of
the combining network, shall be modulated with a frequency of 400 Hz at a deviation of 60% of the
maximum permissible frequency deviation, subclause 4.4.1 and adjusted to the frequency 4
neighbouring channels above the nominal frequency of the receiver.
b)
Initially the unwanted test signals shall be switched off (each maintaining its output impedance). The
amplitude of the signal generator A shall be adjusted to produce a level equivalent to a field
strength of 26.0 dBµV/m at the receiver input, the level of the limit for the average usable
sensitivity, subclause 5.1.4.
c)
The two unwanted test signals shall then be switched on. The amplitude of the two unwanted
signals shall be maintained equal and shall be adjusted until the SINAD ratio, through a
psophometric weighting network is reduced to 14 dB. The frequency of signal generator B shall be
adjusted to produce the maximum degradation of the SINAD ratio. The level of the two unwanted
test signals shall be readjusted to restore the SINAD ratio of 14 dB.
The level of the unwanted signals, expressed as field strength, is calculated by taking the average
usable sensitivity limit, subclause 5.1.4, and adding to that limit the difference in dB between the
output of signal generator B (or C) and A.
This level shall be recorded.
d)
The intermodulation response rejection shall be recorded as the level of the unwanted signals at the
receiver input for which the specified reduction in SINAD occurs.
e)
The measurements shall be repeated with the unwanted signal from the generator B at the
frequency 2 neighbouring channels below that of the wanted signal and with the unwanted signal
from the generator C at the frequency 4 neighbouring channels below that of the wanted signal.
5.7.3.2
Limits
 70.0 dBµV/m for unwanted signal frequencies  68.0 MHz and
 (20 log10f + 33.5) dBµV/m for unwanted signal frequencies > 68.0 MHz, where f is the frequency
in MHz.
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5.8
Blocking or desensitisation
5.8.1
Definition
Blocking is a change (generally a reduction) in the wanted audio output power of a receiver or a reduction of
the SINAD ratio due to an unwanted signal on another frequency.
5.8.2
Equipment with an external antenna connector
5.8.2.1
Method of measurement
a)
Two input signals from signal generators A and B shall be connected to the receiver via a
combining network, subclause 3.5.
b)
The wanted test signal, represented by the signal generator A connected to one input of the
combining network, shall be at the nominal frequency of the receiver and shall have normal test
modulation, subclause 3.1. The level of the wanted test signal shall be adjusted to obtain at the
receiver input an e.m.f. of 6.0 dBmV, the value of the limit for the maximum usable sensitivity.
Where possible, the receiver volume control shall be adjusted to give at least 50 % of the rated
output power, subclause 3.8, or, in the case of stepped volume controls, to the first step that
provides an output power of at least 50 % of the rated output power. The obtained audio output
level shall be noted.
c)
The unwanted test signal, at a frequency from 1 MHz to 10 MHz offset from the nominal frequency
of the receiver, without modulation, shall be applied to the receiver input connector via the second
input of the combining network.
d)
For practical reasons the measurements shall be carried out at frequencies of the unwanted test
signal at approximately ± 1 MHz, ± 2 MHz, ± 5 MHz and ± 10 MHz, avoiding those frequencies at
which spurious responses occur.
The amplitude of the unwanted test signal shall be adjusted until:
a reduction of 3 dB in the audio output level of the wanted signal, or
the SINAD ratio, psophometrically weighted, at the output of the receiver is reduced to 14
dB,
whichever occurs first. This level shall be noted.
e)
The measure of the blocking or desensitisation is the ratio in dB of the level of the unwanted test
signal to the level of the wanted test signal at the receiver input for which the specified reduction in
audio output level or in the SINAD ratio occurs.
This ratio shall be recorded for each of the eight noted levels as the blocking or desensitisation.
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MPT 1314:1997
5.8.2.2
Limit
The blocking ratio, for any frequency within the specified ranges, shall not be less than 84.0 dB, except at
frequencies on which spurious responses are found, subclause 5.6.
5.8.3
Equipment without an external antenna connector
5.8.3.1
Method of measurement
test site
3
1
4
6
2
5
7
1
2
3
4
5
6
7
Psophometric weighting network and SINAD meter
AF load/acoustic coupler
Receiver under test
Wide band test antenna
Combining network
Signal generator A
Signal generator B
Figure 21: Measurement arrangement
a)
A test site corresponding to that for the measurement of average usable sensitivity shall be used,
subclause 5.2.
The equipment under test shall be positioned in the reference direction recorded in subclause 5.2.2
h).
b)
The two input signals from signal generators A and B shall be connected via a combining network
to the wideband test antenna. The wanted test signal, represented by signal generator A, shall be at
the nominal frequency of the receiver and shall have normal test modulation, subclause 3.1. The
level of the wanted test signal shall be adjusted to obtain at the test antenna a level which is
equivalent to 26.0 dBµV/m, the level of the limit for the average usable sensitivity expressed as a
field strength, subclause 5.2.4.
c)
Where possible, the receiver volume control shall be adjusted to give at least 50 % of the rated
output power, subclause 3.8, or, in the case of stepped volume controls, to the first step that
provides an output power of at least 50 % of the rated output power. The obtained audio output
level shall be noted.
d)
The unwanted test signal, represented by signal generator B, shall provide a frequency from
1 MHz to 10 MHz offset from the nominal frequency of the receiver, without modulation.
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MPT 1314:1997
For practical reasons the measurements shall be carried out at frequencies of the unwanted signal
at approximately ± 1 MHz, ± 2 MHz, ± 5 MHz and ± 10 MHz, avoiding those frequencies at which
spurious responses occur, subclause 5.6.
e)
The amplitude of the unwanted test signal shall be adjusted until:
a reduction of 3 dB in the audio output level of the wanted signal, or
the SINAD ratio, psophometrically weighted, at the output of the receiver is reduced to 14
dB,
whichever occurs first. This level shall be noted.
f)
The measure of the blocking or desensitisation is the lowest of the eight noted levels of the
unwanted test signal at the receiver input for which the specified reduction in audio output level or in
the SINAD ratio occurs.
This level shall be recorded in dBµV/m as the blocking or desensitisation.
5.8.3.2
Limit
89.0 dBµV/m for unwanted signal frequencies 68.0 MHz and
(20 log10f + 52.3) dBµV/m for unwanted signal frequencies > 68.0 MHz, where f is the
frequency in MHz.
5.9
Spurious radiations
5.9.1
Definition
Spurious radiations from the receiver are components at any frequency radiated by the equipment and
antenna.
The level of spurious radiations shall be measured
either as:
the power level in a specified load (conducted spurious emission) and
the effective radiated power when radiated by the cabinet and structure of the equipment (cabinet
radiation),
or as:
the effective radiated power when radiated by the cabinet and the integral antenna, in the case of
equipment fitted with such an antenna and no external antenna connector.
5.9.2
Method of measuring the power level in a specified load
This method applies only to equipment with an external antenna connector.
a)
The receiver shall be connected to a 50  attenuator. The output of the attenuator shall be
connected to a measuring receiver.
b)
The receiver shall be switched on and the measuring receiver shall be tuned over the frequency
range 100 kHz to 4 GHz.
At each frequency at which a spurious component is detected, the power level shall be recorded as
the spurious power level delivered into the specified load.
5.9.3
Methods of measuring the effective radiated power
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5.9.3.1
Equipment with an external antenna connector
test site
1
2
3
1
2
3
Receiver under test
Test antenna
Spectrum analyser or selective voltmeter
Figure 22: Measurement arrangement
a)
A test site conforming with the requirements of subclause 3.10 and which fulfils the requirements of
the specified frequency range of this measurement shall be used. The receiver under test shall be
placed on a non-conducting support and in the position closest to normal use as declared by the
manufacturer. The receiver antenna connector shall be connected to an artificial antenna,
subclause 3.2.
The test antenna shall be orientated for vertical polarisation and connected to a spectrum analyser
or a selective voltmeter. The resolution bandwidth of the spectrum analyser or selective voltmeter
shall be the smallest bandwidth available which is greater than the spectral width of the spurious
component being measured.
b)
The receiver shall be switched on and the radiation of any spurious component shall be detected by
the test antenna and the spectrum analyser or selective voltmeter over the frequency range 25 MHz
to 4 GHz.
The frequency of each spurious component shall be recorded. If the test site is disturbed by
radiation coming from outside, this qualitative search may be performed in a screened room with
reduced distance between the transmitter and the test antenna.
c)
At each frequency at which a component has been detected, the spectrum analyser or selective
voltmeter shall be tuned and the test antenna shall be raised or lowered through the specified
height range until the maximum signal level is detected on the spectrum analyser or selective
voltmeter.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3 (i.e. an anechoic chamber).
d)
The receiver shall be rotated up to 360° about a vertical axis, until higher maximum signal is
received.
e)
The test antenna shall be raised or lowered again through the specified height range until a
maximum is obtained. This level shall be recorded.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3 (i.e. an anechoic chamber).
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MPT 1314:1997
test site
2
3
1
1
2
3
4
4
Signal generator
Substitution antenna
Test antenna
Spectrum analyser or selective voltmeter
Figure 23: Measurement arrangement
f)
Using measurement arrangement shown in figure 23, the substitution antenna shall replace the
receiver antenna in the same position and in vertical polarisation. It shall be connected to the signal
generator.
g)
For each frequency at which a component has been detected, the signal generator and spectrum
analyser or selective voltmeter shall be tuned and the test antenna shall be raised or lowered
through the specified height range until the maximum signal level is detected on the spectrum
analyser or selective voltmeter.
The test antenna need not be raised or lowered if the measurement is carried out on a test site
according to subclause 3.10.3 (i.e. an anechoic chamber).
The level of the signal generator giving the same signal level on the spectrum analyser or selective
voltmeter as in step e) shall be recorded. This value, after correction due to the gain of the
substitution antenna and the cable loss between the signal generator and the substitution antenna,
is the radiated spurious component at this frequency.
h)
Measurements b) to g) shall be repeated with the test antenna orientated in horizontal polarisation.
5.9.3.2
Equipment without an external antenna connector
The method of measurement shall be performed according to subclause 5.9.3.1 except that the receiver
input shall be connected to the integral antenna and not to an artificial antenna.
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5.9.4
Limits
The power of any spurious radiation shall not exceed the values specified in tables 9 and 10.
Table 9:
Conducted components
Frequency range
100 kHz to 1 GHz
>1 GHz to 4 GHz
Limit
2.0 nW
20.0 nW
Table 10:
6
6.1
Radiated components
Frequency range
25 MHz to 1 GHz
>1 GHz to 4 GHz
Limit
2.0 nW
20.0 nW
REQUIREMENTS FOR EQUIPMENT EMPLOYING SELECTIVE SIGNALLING
General
The equipment fitted with a continuous tone controlled signalling system (CTCSS) should meet the
requirements of the Code of Practice MPT 1306.
The equipment using sequential tone signalling should conform with the requirements of the Code of Practice
MPT 1316.
The equipment including a binary signalling system should be in accordance with the standards of the Code
of Practice MPT 1317.
The equipment employing selective signalling only shall meet the requirements of subclauses 4.1, 4.2, 4.3,
4.7 and 5.9. In addition, the equipment shall meet the requirements specified in subclauses 6.8, 6.10, 6.11
and 6.12.
6.2
Calling indicator
The calling indicator may be any suitable means of indicating that the receiver has responded to a correctly
coded input signal may be used.
6.3
Reset
The reset may be a manual or automatic method of cancelling the calling indication and resetting the
decoder enabling it to respond to the next correctly coded input signal.
6.4
Reset time
The reset time of the receiver is the minimum elapsed time between two calls in order that both may be
registered successfully. The reset time shall be declared by the manufacturer in order that the formation of
the normal coded test signal may be derived.
6.5
Normal coded test signal
The normal coded test signal shall be defined such that it requires the greatest occupied radio modulation
bandwidth. Details of the test signal shall be included in the test report.
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6.5.1
Equipment employing sequential tone signalling
The normal coded test signal shall comprise trains of correctly coded signals, messages or tones separated
from each other by a time of not less than the reset time of the receiver. Each information, e.g. selective call,
shall not be longer than about 400 ms.
6.5.2
Equipment employing bit signalling
The normal coded test signal shall comprise trains of correctly coded bits or correctly coded signals
(messages), if possible of length 22 bits.
6.6
Encoder
To facilitate measurements on the receiver, an encoder for the signalling system should accompany the
model submitted complete with details of the normal modulation process. The encoder shall be used to
modulate a signal generator for use as a test signal source.
If possible, the encoder should be capable of operation in a repetitive mode with intervals between each code
which are not less than the reset time of the associated receiver.
Complete details of all codes and of the code format(s) shall be given.
Details concerning the interconnection of the encoder and the signal generator shall be agreed between the
manufacturer and the testing authority.
6.7
Facilities for access
When possible, in order to simplify the measurement in subclause 6.11, a temporary access between the
receiver demodulator output and its decoder input shall be provided for the equipment to be tested.
6.8
6.8.1
Transmitter adjacent channel power
Definition
The adjacent channel power is that part of the total output power of a transmitter, under defined conditions of
modulation, which falls within a specified bandpass centred on the nominal frequency of either of the
adjacent channels.
This power is the sum of the mean power produced by the modulation, hum and noise of the transmitter.
6.8.2
Method of measurement
The method of measurement shall be as in subclause 4.5.2 except that the transmitter shall be modulated, in
accordance with the manufacturer's instructions, by the normal coded test signal specified in subclause 6.5.1
or 6.5.2 as applicable. If possible, this should be continuous modulation for the duration of the measurement.
6.8.3
Limit
The adjacent channel power shall not exceed a value of 55.0 dB or 65.0 dB (for 12.5 kHz or 25 kHz channel
spaced equipment respectively) below the transmitter carrier power without the need to be below 0.20 µW.
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MPT 1314:1997
6.9
6.9.1
Reference sensitivity (response)
Definition
In the case of degradation measurements, a reference sensitivity is used which is defined as follows.
The reference sensitivity (response) of the receiver is the minimum level of signal, to be provided at the
receiver input terminals as e.m.f. or as field strength, by a generator operating at the nominal frequency of
the receiver and modulated with the normal coded test signal, subclause 6.5, which will be used as a
reference for the degradation measurements.
The reference sensitivity (response) for normal test conditions is a level of + 6.0 dBµV e.m.f. or a field
strength of 26.0 dBµV/m.
6.10
6.10.1
Maximum usable sensitivity (responses, conducted)
Definition
The maximum usable sensitivity (responses, conducted) of the receiver is the minimum level of the RF signal
(e.m.f.) at the receiver input, at the nominal frequency of the receiver, with normal coded test signal
(subclause 6.5) which without interference will produce after demodulation a signal with a specified
successful response rate of 80 %.
6.10.2
Method of measurement
a)
A signal of carrier frequency equal to the nominal frequency of the receiver and modulated with the
normal coded test signal, subclause 6.5, in accordance with instructions of the manufacturer (and
approved by the type testing authority) shall be applied to the receiver input terminals.
b)
The level of this signal shall be such that a successful response rate of less than approximately 10
% is obtained.
c)
The normal coded test signal shall be transmitted repeatedly whilst observing in each case whether
or not a successful response is obtained. The input level shall be increased by 2 dB for each
occasion that a successful response is not obtained. The procedure shall be continued until three
consecutive successful responses are observed. The level of the input signal shall be recorded.
d)
The input signal shall be reduced by 1 dB and the new value recorded. The normal coded test
signal shall then be transmitted 20 times. In each case, if a response is not obtained the input level
shall be increased by 1 dB and the new value recorded. If a successful response is obtained, the
input level shall not be changed until three consecutive successful responses have been obtained.
In this case, the input level shall be reduced by 1 dB and the new value recorded.
No input signal levels shall be recorded unless preceded by a change in level.
e)
The maximum usable sensitivity is the average of the values recorded in steps c) and d).
f)
The measurement shall be repeated under extreme test conditions, subclauses 2.4.1 and 2.4.2
applied simultaneously.
6.10.3
Limits
The maximum usable sensitivity shall not exceed an e.m.f. of + 3.0 dBµV under normal test conditions and
an e.m.f. of + 9.0 dBµV under extreme test conditions.
6.11
Maximum usable sensitivity (responses, field strength)
This method applies only to equipment without an external antenna connector.
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MPT 1314:1997
6.11.1
Definition
The maximum usable sensitivity of the receiver (responses, field strength) is the minimum field strength
present at the location of the receiver, at the nominal frequency of the receiver and modulated with normal
coded test signal, subclause 6.5, which will fulfil the requirements of subclause 6.10.
6.11.2
Test conditions
Three test conditions are specified.
a)
The manufacturer declares the direction corresponding to the maximum usable sensitivity, in this
case this position shall be used to perform the measurement in subclause 6.11.3.
b)
If the manufacturer does not declare the position corresponding to the maximum usable sensitivity
but provides an analogue output according to subclause 6.7, then this output shall be used to
determine the direction of the maximum usable sensitivity. This shall be the position used for the
measurement in subclause 6.11.3.
c)
If the direction corresponding to the maximum usable sensitivity cannot be determined as specified
in a) or b), then an initial position shall be used and the measurement in subclause 6.11.3 shall be
repeated with eight positions, 45° apart. The maximum usable sensitivity shall be determined from
the minimum field strength recorded.
6.11.3
Test procedure
Arrangements shall be made by the manufacturer to provide a facility to give access to the analogue
information, subclause 6.7, in a way that does not affect the radiated field. This analogue access shall be
used to find the minimum of field strength for the maximum sensitivity, as indicated in the text which follows.
On a test site, fulfilling the requirements of subclause 3.10, the equipment shall be placed at the specified
height on a non-conducting support and in the position closest to normal use as declared by the
manufacturer. This position shall be recorded in the test report.
The test antenna shall be orientated for vertical polarisation and the length of the test antenna shall be
chosen to correspond to the frequency of the receiver.
The input of the test antenna shall be connected to a signal generator. The signal generator shall be tuned to
the frequency of the receiver under test and its output level shall be adjusted to 100 dBµV.
The signal generator shall have normal test modulation, subclause 3.1 . The analogue information shall be
monitored and used to find the two minima of field strength.
The test antenna shall be raised and lowered through the specified range of height to find the lowest level of
the test signal necessary, that is, one of the minima of field strength. The receiver shall then be rotated
through 360o in the horizontal plane, to find again the lowest level of the test signal necessary, that is, the
second of the minima.
The test antenna need not be raised or lowered if the measurement is carried out on a test site according to
subclause 3.10.3.
Under these test conditions and positions and using the test antenna and the signal generator connected to
it, the actual sensitivity will be measured using the method described in subclause 6.10.2.
The input signal level to the test antenna shall be set to the average of the values recorded, subclause 6.10.2
e).
The receiver shall then be replaced by a substitution antenna as defined in subclause 3.14.
The substitution antenna shall be orientated for the vertical polarisation and the length of the substitution
antenna shall be adjusted to correspond to the frequency of the receiver.
The substitution antenna shall be connected to a calibrated measuring receiver.
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MPT 1314:1997
The test antenna shall be raised and lowered through the specified range of height to ensure that the
maximum signal is received.
The test antenna need not be raised or lowered if the measurement is carried out on a test site according to
subclause 3.10.3.
The measured signal level shall be noted as field strength in dBµV/m.
The measurement shall be repeated with the test antenna and the substitution antenna orientated for
horizontal polarisation.
The maximum usable sensitivity, expressed as a field strength, is equal to the minimum of the two signal
levels noted at the input to the calibrated measuring receiver, corrected for the known relationship when
necessary.
6.11.4
Limit
The maximum usable sensitivity shall not exceed the field strength value of 23.0 dBµV/m.
6.12
6.12.1
Adjacent channel selectivity
Definition
The adjacent channel selectivity is the capability of the receiver to achieve a specific successful response
ratio when receiving the wanted signal in the presence of an unwanted signal which differs in its frequency
from the wanted signal by an amount equal to the adjacent channel separation for which the equipment is
intended.
6.12.2
a)
Method of measurement
Two signal generators A and B shall be connected to the receiver via a combining network,
subclause 3.5 or 3.6 refers as applicable.
Signal generator A shall be at the nominal frequency of the receiver and shall be modulated with the
normal coded test signal, subclause 6.5.
Signal generator B shall be modulated with a frequency of 400 Hz at a deviation of ± 1.5 kHz and
shall be adjusted to the frequency of the channel immediately above that of the wanted signal.
b)
Initially signal generator B shall be switched off. Signal generator A will be used for the wanted
signal whose amplitude shall be adjusted to the level of the reference sensitivity (response) at the
receiver input terminals according to subclause 6.9.1, i.e. to 6.0 dBµV.
c)
The unwanted signal (generator B) shall then be switched on and the input level adjusted until a
successful response rate of less than 10 % is obtained.
d)
The normal coded test signal shall be transmitted repeatedly whilst observing in each case whether
or not a successful response is obtained. The level of the unwanted signal shall be reduced by 2 dB
for each occasion in which a successful response is not obtained. The procedure shall be continued
until three consecutive successful responses are observed. The level of the input signal shall then
be recorded.
e)
The level of the unwanted input signal shall be increased by 1 dB and the new value recorded. The
normal coded test signal shall then be transmitted 20 times. In each case, if a response is not
obtained the level of the unwanted signal shall be reduced by 1 dB and the new value recorded.
If a successful response is obtained, the level of the unwanted signal shall not be changed until
three consecutive successful responses have been obtained. In this case the unwanted signal shall
be increased by 1 dB and the new value recorded.
No levels of the unwanted input signal shall be recorded unless preceded by a change in level.
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MPT 1314:1997
f)
The measurement shall be repeated with the unwanted signal at the frequency of the channel below
that of the wanted signal.
g)
The adjacent channel selectivity is the ratio in dB of the average of the levels recorded in steps d)
and e) to the reference level (generator A) of 6.0 dBµV emf. The adjacent channel selectivity for the
equipment under test is the lower value measured in the upper and lower channel nearest to the
receiving channel.
h)
The measurement shall be repeated under extreme test conditions, subclauses 2.4.1 and 2.4.2
applied simultaneously, using the level of the reference sensitivity (response), subclause 6.9.1,
increased by 6 dB to an e.m.f. of 12.0 dBµV.
6.12.3
Limits
The adjacent channel selectivity shall not be less than 60.0 dB or 70.0 dB under normal test conditions and
not less than 50.0 dB or 60.0 dB under extreme test conditions (for 12.5 kHz or 25 kHz spaced equipment
respectively).
7
ACCURACY OF MEASUREMENTS
The overall accuracy of measurements shall be as follows:
*
DC voltage
<±1%
*
AC voltage
<±3%
*
AC mains frequency
*
Audio frequency voltage, power etc.
*
Audio frequency
<±1%
*
Distortion, noise etc. of audio frequency generators
<±1%
*
Radio frequency
*
Radio frequency voltage
< ± 2 dB
*
Radio frequency field strength
< ± 3 dB
*
Radio frequency carrier power
< ± 10 %
*
Adjacent channel power
< ± 3 dB
*
Impedance of artificial loads, combining units, cables, plugs, attenuators etc.
<±5%
*
< ± 10 %
*
Source impedance of generators and input impedance of measuring
receivers
Attenuation of attenuators
*
Temperature
< ± 1 °C
*
Humidity
<±5%
8
< ± 0.5 %
< ± 0.5 dB
< ± 50 Hz
< ± 0.5 dB
INTERPRETATION OF THIS SPECIFICATION
In cases of doubt about the interpretation of this specification, the methods of carrying out the tests and the
validity of statements made by the manufacturers of the equipment, the decision of the
Radiocommunications Agency shall be final.
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ANNEX A:
GUIDANCE ON THE USE OF RADIATION TEST SITES
For measurements involving the use of radiated fields, use may be made of a test site in conformity with the
requirements of subclause 3.10 of this specification. When using such a test site, the conditions outlined in
subclauses A.1 to A.6 should be observed to ensure consistency of measuring results.
A.1
Measuring distance
Evidence indicates that the measuring distance is not critical and does not significantly affect the measuring
results, provided that the distance is not less than a half wavelength at the frequency of measurement and
the precautions described in this specification are observed. Measuring distances of 3 m, 5 m, 10 m and 30
m are in common use in European test laboratories.
A.2
Test antenna
Different types of test antenna may be used, since performing substitution measurements reduces the effect
of the errors on the measuring results.
Height variation of the test antenna over a range of 1 m to 4 m is essential in order to find the point at which
the radiation is a maximum.
Height variation of the test antenna may not be necessary at frequencies below approximately 100 MHz.
A.3
Substitution antenna
Variations in the measuring results may occur with the use of different types of substitution antenna at
frequencies below approximately 80 MHz. Where a shortened dipole antenna is used at these frequencies,
details of the type of antenna used should be included with the results of the tests carried out on the site.
Correction factors shall be taken into account when shortened dipole antennas are used.
A.4
Artificial antenna
The dimensions of the artificial antenna used during radiated measurements should be small in relation to
the sample under test.
Where possible, a direct connection should be used between the artificial antenna and the test sample.
In cases where it is necessary to use a connecting cable, precautions should be taken to reduce the radiation
from this cable, for example, by the use of ferrite cores or double screened cables.
A.5
Auxiliary cables
The position of auxiliary cables (power supply and microphone cables, etc.) which are not adequately
decoupled may cause variations in the measuring results. In order to get reproducible results, cables and
wires of auxiliaries should be arranged vertically downwards (through a hole in the non-conducting support).
A.6
Identification of radiated components
The method of measurement for conducted spurious emissions, subclause 4.7.2, can be used to identify
some radiated spurious emissions and radiations.