1、STD-CEPT ERC REPORT LB-ENGL 1993 111 232b4L4 OOL5L29 4L5 I ERC REPORT 18 w European Radiocommunications Committee (ERC) . within the European Conference of Postal and Telecommunications Administrations (CEPT) * %- ._. SPURIOUS EMISSIONS AND LIMIT VALUES THEREOF Montreux, October 1993 STD-CEPT ERC RE
2、PORT 18-ENGL 1993 I Z32b434 0025330 137 II Copyright 1994 the European Conference of Postal and Telecommunications Administrations (CEP“) STD-CEPT ERC REPORT 38-ENGL 3993 I 232b434 0035333 073 ERC REPORT 18 Page 1 SPURIOUS EMISSIONS AND LIMIT VALUES THEREOF 1. INTRODUCTION Studies have been carried
3、out by Working Group SE on spurious emissions and limit values thereof appropriate to provide a satisfactory environment for the operation of radio systems. 2. SUMMARY OF FINDINGS Earlier studies had shown that the setting of generic limit values for all the parameters needed for spectrum management
4、 was not possible. In order to perform adequately the necessary compatibility evaluation and/or make stipulations on system performance it would generally be necessary to perform calculations on specific systems on a case by case basis. For a few parameters, particularly spurious emissions, frequenc
5、y dependency may not need to be considered and the necessary protection may be directly related to the parameters of the victim system and the expected physical separation due to operational scenarios. This method is discussed below. Based on this methodology and other considerations, target values
6、for spurious emissions have been established. 3. DEFINITIONS For the purpose of this study the dennitions of Article 1 of the Radio Regulations were used. Existing specifications use various terms for elements of Unwanted Emissions such as broadband noise, transient emissions, products due to switch
7、ing and modulation, etc. These vary in definition from one specification to another and can make the interpretation of the specifications difficult. For the purposes of this Report the term “Earth Station“ excludes VSATs (Very Small Aperture Terminals). 4. METHODOLOGY FOR THE DERIVATION OF LIMIT VAL
8、UES FOR SPURIOUS EMISSIONS 4.1 General The methodology used can be briefly described by the three following steps : - the collection of relevant parameters of existing systems in the whole spectrum to determine the protection they need in their receiving band(s); the evaluation from these parameters
9、, using realistic scenarios, of the maximum allowable spurious emission a system can produce without disturbing other systems in their receiving bands (in all calculations the flat earth propagation model is assumed); the setting of guidelines for general limits based on the above calculations. - -
10、The approach of using “worst case“ conditions, that is, in considering the interaction of two systems, estimating the minimum possible separation distance and deducing limits for spurious emissions to avoid interference was rejected as being likely to lead to limits which would be unnecessarily stri
11、ngent, possibly unachievable, and of little practical use. Instead, realistic situations were considered, taking into account probabilities when determining a scenario of interference between systems. Some of these probabilistic assessments are reflected in the calculations when determining an isola
12、tion distance and a systematic isolation between systems. (However, others, such as the distribution of wanted signal levels and time-related aspects, have not been treated fully.) Of course, choices had to be made when defining typical figures for these two parameters and it may be thought that oth
13、er values would be more accurate in particular cases. The choices presented have been governed by the fact that the aim is not to eliminate all interference but to set sensible limits to avoid a majority of potential interference schemes. STD-CEPT ERC REPORT LB-ENGL 1,993 m 2321,434 005332 TOT II ER
14、C REPORT 18 Page 2 A further simpliying step made in the study was the grouping of systems with similar characteristics (mobiles, base stations etc.) in order to avoid extensive calculations of interference between aU existing systems on a case by case basis and also to try to anticipate future syst
15、ems in protecting them from spurious emissions and in setting some requirements they will have to meet not to disturb already existing systems. 4.2 Receiving parameters of system to protect Without being exhaustive, protection is needed for most typicai existing and forthcoming systems. So, a survey
16、 of radiocommunication systems was conducted and relevant parameters collected for each. For each system, the six following parameters were identified : - field to protect (dB(pV/m) - protection ratio (a) - receiving bandwidth (kHz) - antenna height (m) - antennagain( * Protection ratio usuaiiy depe
17、nds upon the nature of the interfering signal. Since no assumption can be made on the nature of the spurious, the intra-system protection ratio, which has the advantage of always being specified, was generally used; * Receiving bandwidth enables the determination of the required protection against a
18、 wideband spurious; * Antenna height is a parameter used in the fiat earth propagation model; * Antenna gain is sometimes used to convert power sensitivity into field strength sensitivity and is helpfui to assess discrimination between mainlobe and sidelobes; * Propagation losses are calculated at c
19、entre frequency. 4.3 Transmitters The transmitters were gathered into groups of similar characteristics. The aim of this was to avoid a global case by case study with all the systems and to allow general assessments to be made. The transmitter groupings were: - broadcasting transfitter : for large c
20、overage, high mounted (50 m) and omnidkectional antenna; - base station : for large coverage, quite widespread, high mounted (30 m) and omnidirectional antenna; - mobile : widespread, moving, omnidirectional antenna (1.5 m); - earth station : high antenna gain in space direction, few in number, gene
21、rally in rural areas; - radio relay : high mounted antenna, high antenna gain; - radar : on ground, high antenna gain, in rural or suburban areas. STD-CEPT ERC REPORT LB-ENGL 1993 I 2326414 O015133 94b II ERC REPORT 18 Page 3 4.4 Isolation between receivers and spurious emitters The isolation betwee
22、n receivers and spurious emitters was analysed both in terms of isolation distance and systematic isolation. The isolation distance is based upon minimum physical distance between two systems, coordination feasibility, transmitter and receiver density, quality required etc. The systematic isolation
23、is due to antenna discrimination, fading margin, wall attenuation etc. The determination of the values was based upon the assumption of a typical interference scenario likely to occur between one given receiver and one given group of transmitters. So, probabilistic considerations are included in the
24、 choice of both isolation distance and systematic isolation. If a receiver is considered to be uncommon, we can accept a large interference area. In this regard, it should be noted that isolation distance between a common receiving system and one rare spurious emitting system is higher than between
25、this rare system, as a receiver, and the same common system, as a spurious emitter. This is because in the first case, the probability to meet an interference for one given receiver is lower. It should be noted that in determining this minimum isolation the flat earth propagation model was used in c
26、alculations. This is the reason why some isolation distances are quite large. In real cases, site shielding will give higher propagation loss than predicted using the flat earth model. Isolation parameters between receivers and spurious emitters groups are explained in the six tables given in Annex
27、A for the most typical cases. Typical antenna heights for spurious emitters are also defined here and will be used in propagation model. However, some receivers (CB, ILS, TPTS, MLS, TVRO, VSAT .) are not taken into account in these global tables, since these are special systems for which details nee
28、d to be considered. Four types of mobile receivers have been identified: radiomessaging, public radiotelephone, cordless telephone and PMR. In some frequency bands, it is believed that PMR requires the same protection as radiotelephone. In this case, isolation parameters for PMR are identical to iso
29、lation parameters for public radiotelephone. Otherwise, the figures provided in the following general table for PMR have been used. For radar emitters, two difficulties arose : the scanning effect and the low duty cycle. Both lead to an averaging of the interfering signal. The question is then wheth
30、er a receiver is sensitive to peak or mean power ? For digital systems, for example, the peak power is likely to determine whether a bit transmission would be affected or not, and the total Bit Error Ratio will depend on the number of radar pulses, i.e. scanning and duty cycle. It was decided to con
31、sider the peak power, except for radio astronomy, where an “averaging effect“ of 20 dB is assumed. For radar, a 20 dB systematic isolation was also assumed, due to the low probability, when scanning, of having two radars facing one another. 5. APPLICATION OF THE METHODOLOGY 5.1 Basic Calculation The
32、 flat earth propagation model was used to determine the maximum permissible spurious radiation from the above interference criteria and the receiver characteristics. This radiation could be expressed as the total power in the receiver bandwidth or normalised to a power in a unit bandwidth, however t
33、his does not take into account the practicalities of measurement and specification. For incorporation in a standard it is considered necessary to specify a reference bandwidth for the measurement to avoid misinterpretation and to promote automatic measurements. It was noted that, in the case of very
34、 wide band spurious (above 3 MHz), no present spectrum analyser is able to measure the total spurious power. ERC REPORT 18 Page 4 Noting that the reference bandwidth should approximate to the receiving bandwidth to ensure relevant limit values can be determined, when all receiving bandwidths are con
35、sidered it appears possible to reach the following compromise reference bandwidth: Bref = 100 kHz for frequencies between 30 MHz and 1 GHz Bref = 1 MHz for frequencies above 1 GHz and Resulting figures for the maximum spurious power with these reference bandwidths (Bref) are given in Annex B for eac
36、h system to protect against each emitter group. 6. LLMITS DERIVED FROM THE CALCULATIONS As a step in establishing practical limits, it was possible to identify the following frequency bands where. different limits would be applicable as follows (the reference bandwidth for measurements in each band
37、are also mentioned) : - BO: 9kHzto30MH Bref = 9 Wz - B1 : 30 tO23OMHz Bref = 100 kHz - B2: 230tlOOOMHz Bref = 100 kHz - B3: 1000 to 3400 MHz Bref = 1 MHz - B4: 3400MHzt030GHz Bref = 1 MHz - B5: above30GHz Bref = 1 MHz For the BO band, it seems not to be relevant to set radiation limits. Moreover, th
38、ere are not enough systems considered in this study below 30 MHz to assess the relevant limits. No systems have been considered in the B5 band and, for these high frequencies, some testing difficulties could occur. This requires further study. Only limits for B1, B2, B3 and B4 will therefore be give
39、n. A choice of more frequency bands could give some more accurate limits but would increase the inflexibility and the complexity of the limits. A single limit can be specified for each emitter group by considering that all receivers have to be protected (except radio astronomy, because some too stri
40、ngent limits would be required) meaning that the most stringent limit is applied. The resulting limits are shown in the table below (for each figure, the systems giving the limit are identified). TAFLE 1 RADIATED SPURIOUS LIMITS (dBm) 1 I SPURIOUS TRANSMITTER B1 I B2 I B3 I B4 Broadcasting -59 TV I
41、I -46 R 2000 base I (-18 “en route“ radar) 1-24 MLS -1 8 on ground TFS -67 Eurosignai the “coordination distance“ is the subjective distance from which people setting equipment will take care of other existing stations; “height difference“ means that the spurious is not emitted in the same plane as
42、the wanted signal; “walls“ give a systematic isolation (10 dB before 1 GE, 20 dB above) when receiver is inside and emitter outside (or conversely); “low protection“ means that it is acceptable to find some areas where the receiver is affected by interference. The area radius also depends upon the i
43、nterference probability; “fading margin is the value to add to the sensitivity to find the mean wanted signal. - - - - - Table 1-Broadcasting transmitter (50 m antenna height) : receiver broadcasting : -Tv - radio mobile : - radiomessagery - PMR - public radiotel. - cordless tel. base station earth
44、station radio relay radio astronomy radar systematic isolation (a) 8-16 10 30 20-35 20-35 20-30 0-10 30-70 30-50 35-80 30 comments on systematic isolation yagi antenna directivity height difference walls & height difference height difference & fading height difference & fading wails &height differen
45、ce face to face antennas, depending on the antenna height antenna directivity antenna directivity antenna directivity speed and location discrimina- margin margin isolation distance m 500 700 700 3000 1000 700 1 O00 10000 10000 20000 5000 I comments on isolation distance antenna on the roof last flo
46、or in a building last floor in a building street and low quality street last floor in a building minimum urban coordination distance rurai coordination distance rural coordination distance rural coordination distance suburban coordination distance STDmCEPT ERC REPORT LB-ENGL 1993 I 2326414 nn1533q 3
47、b4 antenna directivity mobile in the main beam antenna directivity speed and location discrimina- ERC REPORT 18 Page 10 1000 5 O00 1000 1000 Table 2-Mobile Transmitter (1.5 m antenna height) : - public radiotel. - cordless tel. base station earth station radio relav receiver 20-35 20-30 O 30-70 30-5
48、0 roadcasting : TV radio nobile : radiomessagery PMR public radiotel. cordless tel. ase station wth station adio relay ,adio astronomy ,adar systematic isolation (a) 18-26 10 30 0-15 0-15 10-20 10-20 30-70 O 35-80 30 comments on isolation systematic isolation distance antenna directivity and height
49、30 difference wall or fading margin 20 Table 3-Base station transmitter (30 m antenna height) : comments on isolation distance distance between antenna on the roof and streets distance between radio inside and mobile outside require protection both in street, low protection both in street street-building distance mobile in a street near the building carrying the base antenna exclusion area around the station minimum distance where it is likely to have a mobile in the main beam exclusion area around the station mobile transmitting in front of the airport hall receiver broadcasting
