1、 Report ITU-R SM.2157 (09/2009) MEASUREMENT METHODS FOR POWER LINE HIGH DATA RATE TELECOMMUNICATION SYSTEMS SM Series Spectrum management Rep. ITU-R SM.2157 ii Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency
2、 spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunic
3、ation Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent s
4、tatements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Reports (Also avail
5、able online at http:/www.itu.int/publ/R-REP/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite
6、services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management Note: This ITU-R Report was approved in English
7、 by the Study Group under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2009 ITU 2009 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rep. ITU-R SM.2157 1 REPORT ITU-R SM.2157 Measurement m
8、ethods for power line high data rate telecommunication systems (Question ITU-R 218/1) (2009) Summary There is an increasing demand for and use of broadband access to the Internet throughout the world. Power line telecommunication systems may provide one means of such access. Such systems are uninten
9、tional emitters of RF radiation, and such unintentional emission may cause interference to radiocommunication receivers. The interference coupling path to victim receivers may be by means of radiated emissions, or may be by means of conducted emissions. Some administrations have already adopted or a
10、re developing methods or procedures for measuring either the radiated emissions or the conducted emissions from power line telecommunication systems, or both. This report is a compilation of those methods and procedures. See Annexes 1 to 6. Other administrations are in the process of evaluating such
11、 measurement methods. Those administrations may wish to consider the methods described in the annexes to this Report. In addition, the International Special Committee on Radio Interference (CISPR), which develops limits and methods of measurement for radio frequency disturbances originating from var
12、ious types of sources, also has work underway on measurement methods for conducted emissions from power line telecommunication systems. 1 Unintentional emissions from PLT systems PLT modems are designed to communicate with each other by transmitting and receiving signals through power lines. Therefo
13、re, in general, the signal power is concentrated in the vicinity of two wires of the power line. However, if the two wires are not well-balanced, the signal power may leak from the power line in the form of radiated emission. Imbalance of the power lines is caused by various loads connected to the l
14、ines, such as electrical or electronic devices, and many branch lines connected in parallel with backbone power lines, such as circuits of lamps with their switches. In addition, branch lines may cause resonance at certain frequencies, resulting in unbalanced signal currents in the lines. Thus, radi
15、ated emission from power lines may be caused by imbalance of the signal currents flowing in the PLT system, including factors such as the PLT modems, layout of the power lines, and varying loads. The imbalance currents in a PLT system may vary with time and frequency. Accordingly, radiated emission
16、levels from a PLT system depend primarily on the signal power of PLT modems, but may change extensively with time, frequency and location (and possibly other factors such as reflective objects that are nearby to the power lines). 2 Measurements on the PLT emissions There are two different categories
17、 of measurements of PLT emissions: radiated emission measurement and conducted emission measurement. 2.1 Radiated emission measurement Electromagnetic fields radiated from a PLT system are usually measured along the power lines or outside the house equipped with PLT systems. In general, field-streng
18、th measurement results strongly depend on the measurement distance and direction from radiating sources, and the 2 Rep. ITU-R SM.2157 polarization and height of an antenna being used. In the HF band, either a loop antenna or a monopole antenna is used for measuring the magnetic field or electric fie
19、ld, respectively. However, it is difficult to mutually convert the measurement data between the magnetic field strength and the electric field strength, especially at a distance less than about /2, because a conversion factor of 377 may not be applicable. Radiated emission measurements are usually c
20、onducted in situ where interference to radio services may occur. However, as described in the previous section, it should be noted that the results may vary with time, frequency, and location. To minimize the likelihood that PLT systems will cause interference, radiated emission measurements are req
21、uired by regulations and standards as shown in Annexes 1 (ITU-T), 2 (United States of America), and 3 (Germany). Annex 4 describes work underway (in Brazil) to correlate radiated measurements that are made with different antenna types. Key factors for the radiated emission measurement are the charac
22、teristics of a measuring receiver and the antenna being used (as discussed in Annexes 3 and 4). In addition, the measurement distance, antenna height, and influence of reflecting objects that may be nearby to measurement positions are also important. Annex 6 contains the methods used by the Communic
23、ations Research Centre to carry out measurements of both radiated and conducted RF emissions from PLT devices operating in a residential environment. The results of these measurements can be found in Report ITU-R SM.2158. 2.2 Conducted emission measurement In contrast to the radiated emission measur
24、ement, the conducted emission measurement may be employed in the equipment authorization test. As described in 2.1, unintentional radiation from a PLT system originates from the imbalance (common mode) currents that are transformed from the balanced (differential mode) signal currents due to imbalan
25、ce and resonance of the PLT system. Therefore, measurements are made on the balance and imbalance components of the signal voltage or current conducted on the power line. In actual situations, however, measurement data may be spread in an extremely wide range, because imbalance in PLT modems, power
26、lines, and connected equipment greatly varies with time and frequency as well as layouts and nearby objects to the power lines. Accordingly, in compliance tests of the PLT modem, a network called an “impedance stabilization network (ISN),” is usually used to simulate representative characteristics o
27、f actual power line conditions. To control interference potential of other kinds of electrical/electronic equipment, such as personal computers and household appliances, conducted emission measurements are always requested to show compliance with relevant limits by various standards such as CISPR st
28、andards, especially in the frequency range below 30 MHz. In the same way, conducted emission measurements can be applied to PLT modems for equipment authorization tests. Annex 5 (Japan) requests measurements of the common mode signal currents flowing out of a modem under test when it is connected to
29、 an ISN. Since the ISN characteristics are strictly specified as a fixed load to the modem, the differential mode signal currents are also restricted by the limits for the common mode currents. Key factors to the conducted emission measurement are the characteristics of a measuring receiver and an I
30、SN being used. Protection requirements for radiocommunication services have to take account of the level of RF energy radiated from PLT systems into free space as well as conducted emissions from PLT systems sharing common electrical power circuits with receiving equipment. However, there is not a w
31、ell-defined correspondence between the RF energy radiated by PLT systems and the values of conducted current measured at the outlets of PLT systems, or the power delivered to power lines by Rep. ITU-R SM.2157 3 PLT modems. This Report includes a method for measuring conducted emissions, but does not
32、 consider whether conducted emissions or radiated emissions should be used for regulating PLT. 2.3 Other relevant ITU-R texts Recommendation ITU-R SM.1753 Method for measurements of radio noise. Recommendation ITU-R P.372-9 Radio Noise. Report ITU-R SM.2055 Radio noise measurements. Report ITU-R SM.
33、2155 Man-made noise measurements in the HF range. Annex 1 Disturbance emission measurements from ITU-T Recommendation K.601A1.1 General In order to get the highest readings of disturbance emissions, it should be ensured that the part of the telecommunication network being assessed operates at the ma
34、ximum signal levels for this site and in the mode previously identified as resulting in maximum RF disturbance field strength. If the system is interactive, it will be important to check for the presence of the reverse path (upstream) signals if these are in the same frequency range as reported in t
35、he complaint(s). Indoor measurements are particularly subjected to uncertainties due to reflections or unknown cable routes for example. It is important to carefully search for the maximum emission and take into account possible influence factors. Although the measurement of the radiated field has t
36、he drawbacks of a relatively high measurement uncertainty and positioning difficulties, this method is applicable both indoor and outdoor. In addition, when performing indoor measurement, a particular attention to reflections has to be drawn. In certain cases, the field intensity may be double that
37、of the calculated value. A1.2 Normalization of measurement results to the standard measurement distance Local restrictions in space (appearing e.g. during indoor measurements) can require a reduction of the measuring distance to less than the standard measurement distance. The measurement distance c
38、hosen will be as large as possible, but not closer than 1 m. In case of outdoor measurements, it may also be necessary to use a measurement distance which is larger than the standard distance. If a measurement distance greater or smaller than the standard measurement distance needs to be used, then
39、three different and accessible measuring points located along the measuring axis will be chosen. The distance between these points should be as large as possible. At each point, the level of the disturbing field strength has to be measured. The local conditions and measurability of the disturbance f
40、ield strength will be the determining factors. 1The purpose of this Recommendation is to guide administrations when considering complaints of interference between telecommunication systems and is not intended to set compliance requirements or recommendations for protecting the radio spectrum. 4 Rep.
41、 ITU-R SM.2157 The measurement results will then be plotted in a diagram showing the field strength level (dB(V/m) versus the logarithm of the measurement distance. The line interconnecting the measurement results represents the slope in field strength along the measuring axis. If this slope cannot
42、be determined, then additional measuring points have to be chosen. The field strength level at the standard measurement distance can be read from the diagram using the straight prolongation of the interconnecting line. Normalization of measurement results is not permitted if, at the measurement loca
43、tion, the true distance to the telecommunication network cable is not known. A1.3 Disturbance emission measurements in the frequency range 9 kHz to 30 MHz A1.3.1 Introduction In the frequency range 9 kHz to 30 MHz, the magnetic component of the radiated disturbance emission has to be measured and as
44、sessed. A calibrated measuring system, in accordance with CISPR 16-1-1, consisting of a radio disturbance measuring receiver (or a suitable spectrum analyser), in conjunction with an associated loop antenna for the measurement of magnetic field components, and a tripod are required. Other specialize
45、d equipment such as resonant loop antennas can also be used, if necessary. In order to speed up the measurement, a peak detector has first to be used. If the background noise makes this simple measurement unusable, a quasi-peak detector will be used and the quasi-peak level applied. It is recommende
46、d that both the measuring receiver and the loop antenna have an independent power source with no ground connection (e.g. battery power), particularly in case of indoor measurements, in order to minimize the possibility of current loops via earth that could affect the measurement. A1.3.2 Measurement
47、procedure The loop antenna will be mounted on a tripod at a height of 1 m (at the lower edge of the loop) and allocated at the measurement location previously identified as having the maximum disturbance field strength so that it is at the standard measurement distance. Set the measuring receiver to
48、 the frequency carrying the disturbance and type of detector required, and position the loop antenna so that the maximum reading is obtained. The measurement of magnetic fields radiated from telecommunication networks in the frequency range up to 30 MHz may become complicated due to the presence of
49、a variety of high-level wanted RF emissions from radio services. In view of this, it may be necessary to identify some frequencies (hereafter described as “quiet frequencies”) allocated close to the frequency of the radio service being affected, with low field strengths such that the background noise and any ambient signals are below the applicable limit. Where possible, this margin should be greater than 6 dB. This should be done without altering the antenna position, and ideally with the telecommunication network switched off. If the network cannot be switched off, then t
