Radiocommunications Agency
MPT 1570 (July 99 draft)
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
MPT 1570
Radiation Limits and Measurement
Standard
Electromagnetic radiation from telecommunications
systems operating over material substances
in the frequency range 9 kHz to 300 MHz
[ July 1999 ]
RADIOCOMMUNICATIONS AGENCY
Wyndham House
189 Marsh Wall
LONDON
E14 9SX
Tel. 0207 211 0211
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1570_1.doc
Radiocommunications Agency
MPT 1570 (July 99 draft)
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Contents
1.0
Introduction
Page _3
2.0
Definition of telecommunications systems utilising material substances
Page _4
3.0
Application
4.0
Interpretation
5.0
Revisions
--------------------------------------------------------------
Electromagnetic radiation from Wired Telecommunications Systems
operating in the frequency range:
6.0
PART A:
9 kHz to 150 kHz
Page_5
7.0
PART B:
150 kHz to 1.6 MHz.
Page_6
Principle
Equipment
Measuring System Sensitivity
Measurement Frequencies
Limits
Method
Preliminary Investigations
Measurement Procedure
Chart of Emission Limit from 150 kHz to 1.6 MHz
8.0
PART C:
1.6 MHz to 30 MHz.
Page_9
Principle
Equipment
Measuring System Sensitivity
Measurement Frequencies
Limits
Method
Preliminary Investigations
Measurement Procedure
Chart of Emission Limit from 1.6 to 30 MHz
9.0
PART D:
30 MHz to 300 MHz
Page_12
--------------------------------------------------------------
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Radiocommunications Agency
MPT 1570 (July 99 draft)
1.0
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Introduction
1.1
Telecommunications systems utilising material substances can be a source of
interference to a wide range of radio services that use the radio frequency spectrum.
1.1.1
1.2
These include not only the emergency services, safety of life, broadcasting,
aeronautical, military and radio navigation services but also cordless
telephones, land mobile and hobby radio services.
The range of radio services considered liable to the threat of interference from
telecommunications systems utilising material substances fall into two broad types:
1.2.1
The first is radio receiving equipment operating in a high wanted signal
environment, but most frequently located very close to telecommunications
systems utilising material substances
(mainly broadcast receivers and cordless telephones )
1.2.2
The second is radio communication equipment operating with low level
wanted signals requiring the use of efficient external antennas.
( most other types )
1.3
Because there is a need to protect existing and projected radio services, falling into
both of the types described above, the Radiocommunications Agency has determined
limits of radiation from telecommunications systems utilising material substances for
both threat categories and methods by which the radiation shall be measured in each
case.
1.4
The measurement procedures outlined in this standard are primarily intended for use
by Radiocommunications Agency staff tasked with investigating complaints of radio
interference from telecommunications systems utilising material substances.
1.4.1
While they may have application for telecommunication system operators and
others, the measurement procedures in this standard are not intended as a
vehicle by which overall system compliance may be determined.
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MPT 1570 (July 99 draft)
2.0
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Definition of "telecommunications systems utilising material substances"
This MPT standard is the standard referred to in the Wireless Telegraphy ( Control of Interference
from Telecommunications Systems Utilising Material Substances ) Regulations 1999.
Notwithstanding the legal interpretation in those Regulations, this standard relates to systems for
carrying information in analogue or digital form, whether for use by individuals ( as speech, video or
data ) or for controlling machinery or processes. The " material substances " over which information
may be carried can be wires, cables, fibre -optic cables etc and they may be buried, supported or
suspended in or on any manner of ways.
2.1
Examples
Where data or speech are transmitted over mains cabling through being modulated on to
electromagnetic waves ( often referred to as " radio frequency "); or
where video or data are transmitted in similar manner over pairs of telephone wires; or
where house electric wiring is used to carry telephone signals at radio frequencies to save installing
separate extension cables.
Generally, but not always, the apparatus is being used for a purpose for which it was not originally
designed, intended or installed and because the system is not properly shielded or balanced, radio
frequency energy can escape.
3.0
Application
The Radiocommunications Agency has established the maximum permissible levels of radiation from
telecommunications systems utilising material substances operating in the frequency range 9 kHz to
300 MHz. This standard sets out the procedure to be adopted for the measurement of that radiation.
3.1
Operators of telecommunications systems utilising material substances requiring further
information on the application of this standard should apply to:
Enforcement Policy Unit
Customer Services Executive
Radiocommunications Agency
Wyndham House
189 Marsh Wall
LONDON E14 9SX
Tel:
0207-211 0470 / 0455
4.0
Interpretation
In cases of doubt regarding the interpretation of this standard or the method of carrying out the
measurements, the decision of the Radiocommunications Agency shall be final.
5.0
Revisions
The Radiocommunications Agency reserves the right to amend this standard without notice when
necessary.
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Radiocommunications Agency
MPT 1570 (July 99 draft)
6.0
PART A:
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Electromagnetic radiation from Telecommunications Systems operating
over material substances in the frequency range 9 kHz to 150 kHz.
LIMITS AND MEASUREMENT METHODS ARE UNDER CONSIDERATION
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MPT 1570 (July 99 draft)
7.0
PART B:
7.1
Principle
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Electromagnetic radiation from Telecommunications Systems operating
over material substances in the frequency range 150 kHz to 1.6 MHz.
The limits set for this part of the spectrum are principally intended to afford protection to broadcast
receivers intended for use within the domestic environment.
7.2
7.3
Equipment
7.2.1
A calibrated Measuring Receiver meeting the requirements of CISPR 16-1 for
measurements between 150 kHz and 30 MHz:
(peak detector and 9 kHz measuring bandwidth)
7.2.2
A calibrated Loop Antenna meeting the requirements of CISPR 16-1 for
measurements between 150 kHz and 30 MHz:
7.2.3
A tripod for mounting the loop antenna 1 metre above ground level in the vertical
plane and having a facility for orientating the loop in the horizontal plane.
Measuring System Sensitivity
The equipment specified above, should achieve a noise floor equivalent electromagnetic field strength
of not less than [ 4 dB] below the limit field strength at the frequency being measured.
7.4
Measurement Frequencies
Measurements using this method will normally be made at or around the emission frequency giving
rise to a complaint but shall be limited to frequencies between 150 kHz and 1.6 MHz.
7.5
Limits
The maximum permitted Magnetic Field Strength between 150 kHz and 1.6 MHz is calculated using
the formula: [ -11.5 - 20 log f ( MHz ) dB µA/m ]
For the purposes of this document, this is expressed as an Equivalent Electric Field Strength using the
formula: [ 40 -20 log f (MHz) dB µV/m ] but see note below.
NOTE: Magnetic Loop Antennas respond primarily to the magnetic field component of an
electromagnetic wave which is properly expressed in dBµA/m. Loop antenna manufacturers
commonly provide conversion factors for electric field strength, expressed in dBµV/m, by
adding a far field impedance correction of 51.5 dB (20 log 377 Ω). In this case the
measurement distance is clearly within the near field at all frequencies so the far field
impedance conversion is technically incorrect but used here by convention to refer to an
Equivalent Electric Field Strength.
A Chart showing the limit curves is provided in Section 7.9
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Radiocommunications Agency
MPT 1570 (July 99 draft)
7.6
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Method
This method describes the measurement of electromagnetic field strength at 1 metre spacing from
any material substance forming part of, or connected to, a telecommunication system.
7.7
Preliminary Investigations
7.7.1 Using a portable receiver with a signal level indicator, or other convenient tracing technique,
conduct an investigation to verify that the source of the interference, being complained of, is a
telecommunications systems utilising material substances. Identify and record the location, in the
vicinity of the complainant/s receiving installation/s, where emission levels at 1 metre spacing from any
material substance forming part of, or connected to, a telecommunication system, appear to be
highest.
7.7.2 To avoid unnecessary work, discuss the complaint with the telecommunications system
operators. If necessary, enlist their help to establish that the telecommunications system operating
over material substances is operating with its normal signal levels at the Network Terminating Points
nearest to the complainant. If the system is interactive, it will be particularly important to check the
reverse path (upstream) signal levels if these are in the same frequency range as that of the
complaint.
7.7.3 If the telecommunications system operator declares all levels normal, but the complaint persists
and appears justified, calibrated measurements should be made.
7.8
Measurement Procedure
Mount the loop antenna on a tripod at the location identified in paragraph 7.7.1 above so that the
periphery of the loop is no closer than 1 metre from the telecommunications system operating over
material substances. If it is found necessary to measure emissions from material substances out of
sight behind the surface of a wall or below ground level, then the 1 metre spacing shall be measured
from the loop periphery to the surface of the wall or ground.
NOTE: If the system is interactive, normal levels of reverse path (upstream) signals must be
maintained during the measurements.
7.8.1 Tune the measuring receiver to the frequency of complaint and rotate the loop antenna to
obtain the maximum signal indication on the measuring receiver. Taking care to maintain the
minimum 1 metre measurement distance, move the tripod either side of the measuring position to
ensure the maximum level is obtained. Repeat as necessary on adjacent frequencies to establish any
variations.
7.8.2 Taking into account the antenna calibration factor, record the highest field strength reading
obtained and compare it with the limit in Section 7.5.
7.8.3 The measuring equipment level uncertainty should be taken into account during any
assessment of conformity with the limit values.
------------------------------------------------------------------------------------------------
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MPT 1570 (July 99 draft)
7.9
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Radiated Emission Limit from 150 kHz to 1.6 MHz
Measurement Conditions:
CISPR Measuring Receiver set to 9 kHz ( 10 kHz ) bandwidth and Peak detector
Magnetic Loop Antenna
Limit Curve:
40 - 20 log f (MHz) dB V/m
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MPT 1570 (July 99 draft)
8.0
PART C:
8.1
Principle
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Electromagnetic radiation from Telecommunications Systems operating
over material substances in the frequency range 1.6 to 30 MHz.
The limits for emissions in this part of the spectrum, have been related to the slope of the spectrum
noise floor. They are much lower than can be measured using standard CISPR 16 magnetic loop
measuring antennas. The technique described in this section utilises, recently developed, electrically
small tuned loop measuring antennas which are significantly more sensitive than those previously
available.
8.2
8.3
Equipment
8.2.1
A calibrated Measuring Receiver meeting the requirements of CISPR 16-1 for
measurements between 150 kHz and 30 MHz:
(peak detector and 9 kHz measuring bandwidth)
8.2.2
An electrically small tuned Loop Antenna calibrated for measurements between 150
kHz and 30 MHz:
8.2.3
A tripod for mounting the loop antenna 1 metre above ground level in the vertical
plane and having a facility for orientating the loop in the horizontal plane.
Measuring System Sensitivity
The measuring system noise floor equivalent field strength shall not be less than [ 4 dB ] below the
limit field strength at the frequency of measurement.
8.4
Measurement Frequencies
Measurements using this method will generally be made at and around the emission frequency giving
rise to a complaint but shall be limited to frequencies between 1.6 and 30 MHz only.
8.5
Limits
The maximum permitted Magnetic Field Strength between 1.6 MHz and 30 MHz is calculated using
the formula: [ -31.5 - 7.7 log f ( MHz ) dB µA/m ]
For the purposes of this standard the Magnetic Field Strength Limit is expressed as an Equivalent
Electric Field Strength using the formula: [ 20 -7.7 log f (MHz) dB µV/m ] but see note below.
NOTE: Magnetic Loop Antennas respond primarily to the magnetic field component of an
electromagnetic wave which is properly expressed in dBµA/m. Loop antenna manufacturers
commonly provide conversion factors for electric field strength, expressed in dBµV/m, by
adding a far field impedance correction of 51.5 dB (20 log 377 Ω). In this case the
measurement distance is clearly within the near field at all frequencies so the far field
impedance conversion is technically incorrect but used here by convention to refer to an
Equivalent Electric Field Strength.
A Chart showing the limit curves is provided in Section 8.9
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Radiocommunications Agency
MPT 1570 (July 99 draft)
8.6
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Method
This method describes the measurement of low level electromagnetic field strength at a spacing of 3
metres from any material substances forming part of, or connected to, a telecommunication system.
8.7
Preliminary Investigation
8.7.1
Using a portable receiver with a signal level indicator, or other convenient tracing technique,
conduct an investigation to verify that the source of the interference, being complained of, is a
telecommunications systems utilising material substances. Identify and record the location, in
the vicinity of the complainant/s receiving installation/s, where emission levels at 3 metre
spacing from any material substance forming part of, or connected to, a telecommunication
system, appear to be highest.
8.7.2
If appropriate to the type of telecommunication system being investigated, discuss the
complaint with the system operators and enlist their help to establish that the
telecommunication system is operating with its normal signal levels at the Network
Terminating Points nearest to the complainant. With interactive systems, it will be particularly
important to check the reverse path (upstream) signal levels, if these are in the same
frequency range as that of the complaint.
8.7.3
If the system operator declares all levels normal, but the complaint persists and appears
justified, calibrated measurements should be made.
8.8
Measurement Procedure
Mount the loop antenna on a tripod at the location identified in paragraph 8.7.1 above so that the
periphery of the loop is no closer than 3 metres from the telecommunications system operating over
material substances. If it is found necessary to measure emissions from material substances out of
sight behind the surface of a wall or below ground level, then the 3 metre spacing shall be measured
from the loop periphery to the surface of the wall or ground.
NOTE: If the system is interactive, normal levels of reverse path (upstream) signals must be
maintained during the measurements.
8.8.1 Tune the measuring receiver to the frequency of complaint and rotate the loop antenna to
obtain the maximum signal indication on the measuring receiver. Taking care to maintain the
minimum 3 metre measurement distance, move the tripod either side of the measuring position to
ensure the maximum level is obtained. Repeat as necessary on adjacent frequencies to establish any
variations.
8.8.2 Taking into account the antenna calibration factor, record the highest field strength reading
obtained and compare it with the limit in Section 8.5.
8.8.3 The measuring equipment level uncertainty should be taken into account during any
assessment of conformity with the limit values.
--------------------------------------------------------------------
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Radiocommunications Agency
MPT 1570 (July 99 draft)
8.9
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Radiated Emission Limit from 1.6 to 30 MHz
Measurement Conditions:
CISPR Measuring Receiver set to 9 kHz ( 10 kHz ) bandwidth and Peak detector
Magnetic Loop Antenna
Limit Curve:
20 - 7.7 log f (MHz) dB V/m
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Radiocommunications Agency
MPT 1570 (July 99 draft)
9.0
PART D:
RTCG Whyteleafe Surrey
WORD 97 version - September 1999
Electromagnetic radiation from Telecommunications Systems operating
over material substances in the frequency range 30 MHz to 300 MHz.
LIMITS AND MEASUREMENT METHODS ARE UNDER CONSIDERATION
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