Radiocommunications Agency
MPT 1570
RTCG Whyteleafe Surrey
April 2000
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
APRIL 2000
RADIOCOMMUNICATIONS AGENCY
Wyndham House
189 Marsh Wall
LONDON
E14 9SX
Tel. 0207 211 0211
1
116106078
Radiocommunications Agency
MPT 1570
RTCG Whyteleafe Surrey
April 2000
Contents
1.0
Introduction
Page _3
2.0
Definition of telecommunications systems utilising material substances
Page _4
3.0
Application
4.0
Aims
5.0
Revisions
--------------------------------------------------------------
6.0
PART A:
Electromagnetic radiation from Telecommunications Systems
operating over material substances in the frequency range 9 kHz to 150 kHz
Page_5
7.0
PART B:
Electromagnetic radiation from Telecommunications Systems
operating over material substances in the frequency range 150 kHz to 1.6 MHz
8.0
PART C:
Electromagnetic radiation from Telecommunications Systems
operating over material substances in the frequency range 1.6 MHz to 30 MHz
9.0
Page_8
Page_11
PART D:
Electromagnetic radiation from Telecommunications Systems
operating over material substances in the frequency range 30 MHz to 300 MHz
-------------------------------------------------------------
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Page_12
Radiocommunications Agency
MPT 1570
RTCG Whyteleafe Surrey
April 2000
1.0
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, radio controlled clocks 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
electromagnetic 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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Radiocommunications Agency
MPT 1570
2.0
RTCG Whyteleafe Surrey
April 2000
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 2000.
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
electromagnetic radiation from telecommunications systems utilising material substances operating in
the frequency range 9 kHz to 30 MHz. This standard sets out the procedure to be adopted for the
measurement of that radiation.
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
Aims
The emission limits contained in this document are intended to afford general protection to licensed
and licence exempt radio communication services in addition to the specific examples set out in Parts
A & B.
NB.
There is currently no MPT 1570 requirement in respect of Parts C & D.
5.0
Revisions
The Radiocommunications Agency reserves the right to amend this Standard.
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Radiocommunications Agency
MPT 1570
6.0
PART A:
6.1
Principle
RTCG Whyteleafe Surrey
April 2000
Electromagnetic radiation from Telecommunications Systems operating
over material substances in the frequency range 9 kHz to 150 kHz.
The limits set for this part of the spectrum are specifically, but not exclusively, intended to afford
protection to radio receivers incorporated into devices such as, but not limited to, Radio Clocks and
Standard Frequency Generators which are intended for use within buildings.
6.2
6.3
Equipment
6.2.1
A calibrated Measuring Receiver meeting the requirements of CISPR 16-1 for
measurements between 9 kHz and 150 kHz:
(peak detector and 200 Hz measuring bandwidth)
6.2.2
A calibrated Loop Antenna meeting the requirements of CISPR 16-1 for
measurements between 9 kHz and 150 kHz:
6.2.3
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 6 dB below the limit field strength at the frequency being measured. (see 6.9 )
6.4
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 9 kHz and 150 kHz.
6.5
Magnetic Field Limit
The maximum permitted Magnetic Field Strength between 9 kHz and 150 kHz is calculated using the
formula: [ 22 - 20 log f (kHz) dB µA/m ]
For the purposes of this document, this is expressed as an Equivalent Electric Field Strength using
the formula: [ 73.5 -20 log f (kHz) 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 6.9
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Radiocommunications Agency
MPT 1570
6.6
RTCG Whyteleafe Surrey
April 2000
Method
This method describes the measurement of electromagnetic field strength at 1 metre spacing from the
nearest accessible point to any material substance forming part of, or connected to, a
telecommunication system.
6.7
Preliminary Investigations
6.7.1
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/s,
in the vicinity of the complainant/s receiving installation/s, where emission levels at 1 metre
spacing from the nearest accessible point to any material substance forming part of, or
connected to, a telecommunication system, appear to be highest.
6.7.2
If appropriate to the type of system being investigated, 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.
6.7.3
If the telecommunications system operator declares all levels normal, but the complaint
persists and appears justified, calibrated measurements should be made.
6.8
Measurement Procedure
Mount the loop antenna on a tripod at the location identified in paragraph 6.7.1 above so that the
periphery of the loop is 1 metre from the nearest accessible part of 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.
6.8.1
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
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.
6.8.2
Taking into account the antenna calibration factor, record the highest field strength reading
obtained and compare it directly with the limit in Section 6.5.
6.8.3
The Agency expects the measurement uncertainty to be in the range  6 dB but intends to
determine limit compliance probability on a shared risk basis using the procedure indicated
above.
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Radiocommunications Agency
MPT 1570
6.9
RTCG Whyteleafe Surrey
April 2000
Radiated Emission Magnetic Field Limit from 9 kHz to 150 kHz
Magnetic Field Limit:
The diagonal line represents the Magnetic Field Limit expressed as an Equivalent Electric Field in
accordance with the formula: [73.5 -20 log f (kHz) dB µV/m ]
NB.
This is NOT an Electric Field Strength Limit
Measuring System Noise Floor:
The lower trace shows the measuring system noise floor using the following equipment:
CISPR Measuring Receiver with a 200 Hz bandwidth and a Peak detector
CISPR Magnetic Loop Antenna
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Radiocommunications Agency
MPT 1570
7.0
PART B:
7.1
Principle
RTCG Whyteleafe Surrey
April 2000
Electromagnetic radiation from Telecommunications Systems operating
over material substances in the frequency range 150 kHz to 1.6 MHz.
Notwithstanding the general aims described in Section 4.0, the limits set for this part of the spectrum
are specifically intended to provide reasonable protection to AM broadcast radio receivers, having
integral ferrite rod antennas, when they are being used within domestic premises.
Reasonable protection is defined as a level of interference causing no worse than a Grade 3
impairment (slightly annoying) on the ITU-R Rec. 562-3, 5 point impairment scale where 'being used'
is receiving an AM Broadcast Transmission at, or greater than, the edge of service area field strength.
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 1.6 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 1.6 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 6 dB below the limit field strength at the frequency being measured. (see 7.9)
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
Magnetic Field Limit
The maximum permitted Magnetic Field Strength between 150 kHz and 1.6 MHz is calculated using
the formula: [ -11.5 – 7.7log f ( MHz ) dB µA/m ]
For the purposes of this document, this is expressed as an Equivalent Electric Field Strength using
the formula: [ 40 – 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 7.9
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116106078
Radiocommunications Agency
MPT 1570
7.6
RTCG Whyteleafe Surrey
April 2000
Method
This method describes the measurement of electromagnetic field strength at 1 metre spacing from the
nearest accessible point to 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 the nearest accessible point to any material substance forming part of, or
connected to, a telecommunication system, appear to be highest.
7.7.2
If appropriate to the system being investigated 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 1 metre from the nearest accessible part of 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
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 directly with the limit in Section 7.5.
7.8.3
The Agency expects the measurement uncertainty to be in the range  6 dB but intends to
determine limit compliance probability on a shared risk basis using the procedure indicated
above.
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116106078
Radiocommunications Agency
MPT 1570
7.9
RTCG Whyteleafe Surrey
April 2000
Radiated Emission Magnetic Field Limit from 150 kHz to 1.6 MHz
Magnetic Field Limit:
The diagonal line represents the Magnetic Field Limit expressed as an Equivalent Electric Field in
accordance with the formula: [40 – 7.7 log f (MHz) dB µV/m]
NB
This is NOT an Electric Field Strength Limit
Measuring System Noise Floor:
The lower trace shows the measuring system noise floor using the following equipment:
CISPR Measuring Receiver with a 9 kHz bandwidth and a Peak detector
CISPR Magnetic Loop Antenna
10
116106078
Radiocommunications Agency
MPT 1570
8.0
PART C:
RTCG Whyteleafe Surrey
April 2000
Electromagnetic radiation from Telecommunications Systems operating
over material substances in the frequency range 1.6 to 30 MHz.
LIMITS AND MEASUREMENT METHODS ARE CURRENTLY UNDER DEVELOPMENT
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116106078
Radiocommunications Agency
MPT 1570
9.0
PART D:
RTCG Whyteleafe Surrey
April 2000
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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