MPT 1570

Radiocommunications Agency

MPT 1570 (dec 99 draft)

RTCG Whyteleafe Surrey

CEPT/ERC/SE (99) PLT11 rev 1

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

[ December 1999 ]

RADIOCOMMUNICATIONS AGENCY

Wyndham House

189 Marsh Wall

LONDON

E14 9SX

Tel. 0207 211 0211

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Contents



1.0

2.0

Introduction

3.0

4.0

5.0

Application

Aims

Revisions

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6.0 PART A:

Electromagnetic radiation from Telecommunications Systems operating over material substances in the frequency range 9 kHz to 150 kHz

Page _3

Definition of telecommunications systems utilising material substances Page _4

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 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_8

Page_11

Page_14

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1.3

1.4


1.2



Introduction 1.0

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 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 )

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.

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 RTCG Whyteleafe Surrey


2.0


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 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


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, & C.

NB There is currently no MPT 1570 requirement in respect of Part D.

5.0 Revisions

The Radiocommunications Agency reserves the right to amend this Standard.

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6.0 PART A:


Electromagnetic radiation from Telecommunications Systems operating over material substances in the frequency range 9 kHz to 150 kHz.

6.2

6.1 Principle

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.

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.

6.3 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 con version 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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6.6 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 with the limit in Section 6.5.

6.8.3 The measuring equipment level uncertainty should be taken into account during any assessment of conformity with the limit values.

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6.9


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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7.0 PART B:


Electromagnetic radiation from Telecommunications Systems operating

over material substances in the frequency range 150 kHz to 1.6 MHz.

7.2

7.1 Principle

The limits set for this part of the spectrum are specifically, but not exclusively, intended to provide reasonable protection to broadcast radio receivers having integral ferrite rod antennas which are intended for use within buildings.

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:


7.3 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 ex pressed 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.


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7.6 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.


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.


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.



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7.9


Radiated Emission Magnetic Field Limit from 150 kHz to 1.6 MHz


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


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

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8.0 PART C:



over material substances in the frequency range 1.6 to 30 MHz.

8.1 Principle

The emission limits for this part of the spectrum are specifically intended to provide reasonable protection to low signal radio communications systems. Such systems will usually be installed in buildings but they will necessarily utilise efficient external receiving antennas so that the overall system sensitivity will allow reception of signals at, or close to, the spectrum noise floor. It is envisaged that the limits set will allow reasonable protection if the external antenna is situated at 10 metres or more from a Telecommunications System operating over material substances.

8.2 Equipment

8.2.1 A calibrated Measuring Receiver meeting the requirements of CISPR 16-1 for measurements between 1.6 and 30 MHz:

(peak detector and 9 kHz measuring bandwidth)

8.2.2 An electrically small, tuned Loop Antenna, with an antenna factor such that the measuring system sensitivity requirements of 8.3 (below) can be met at the frequency of measurement.


8.3

8.4

Measuring System Sensitivity

The equipment specified above should achieve a noise floor equivalent electromagnetic field strength of at least [ 6 dB ] below the limit field strength at the frequency of measurement. (see 8.9)

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 Magnetic Field 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 document, 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.


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8.6 Method



This method describes the measurement of low level electromagnetic field strength at a spacing of 3 metres from the nearest accessible point to 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 the nearest accessible point to 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.


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.


8.8.1 Tune the measuring receiver and the magnetic loop antenna 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.



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8.9


Radiated Emission Magnetic Field Limit from 1.6 to 30 MHz


The diagonal line represents the Magnetic Field Limit expressed as an Equivalent Electric Field in accordance with the formula: [ 20 – 7.7 log f (MHz) dB µV/m ]

NB This is NOT an Electric Field Strength Limit


The lower race shows the measuring system noise floor achieved using the equipment specified:

CISPR Measuring Receiver with a 9 kHz bandwidth and a Peak detector

Magnetic Loop Antenna with an Antenna Factor of – 6.5 dB/m

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9.0 PART D:



over material substances in the frequency range 30 MHz to 300 MHz.

LIMITS AND MEASUREMENT METHODS ARE UNDER CONSIDERATION

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MPT 1570 - Radiation Limits and Measurements Standards

Radiation Limits and Measurement

Standard

Electromagnetic radiation from telecommunications

systems operating over material substances

in the frequency range 9 kHz to 300 MHz

[ December 1999 ]

RADIOCOMMUNICATIONS AGENCY

Wyndham House

189 Marsh Wall

LONDON

E14 9SX

Tel. 0207 211 0211

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