1、Rec. ITU-R SM.851-1 1 RECOMMENDATION ITU-R SM.851-1* SHARING BETWEEN THE BROADCASTING SERVICE AND THE FIXED AND/OR MOBILE SERVICES IN THE VHF AND UHF BANDS (Question ITU-R 2/12) (1992-1993) The ITU Radiocommunication Assembly, considering a frequency bands that might be shared between the broadcasti
2、ng service and the fiied and mobile services; that the World Administrative Radio Conference, (Geneva, 1979) (WARC-79), increased the number of b) the fiied, mobile and broadcasting services on a co-primary basis; that in many parts of the world, some bands are allocated, as specified in Article 8 o
3、f the Radio Regulations, to c that some administrations have partitioned the VHF and UHF bands between the three services and this situation has created some difficulty in coordination between two or more administrations which share borders in the coverage areas and which use these bands for differe
4、nt services; 4 frequency assignment plans and equipment specifications applicable to national and multilateral arrangements; that there is a requirement for standardized compatibility analysis procedures to facilitate the development of e that careful planning of frequency assignments to broadcastin
5、g, fiied and land mobile stations will lead to improvement in spectrum utilization by minimizing harmful interference to operations in the adjacent or shared frequency bands; I) that fiied service applications in many parts of the world presently use the upper part of UHF television bands for radiot
6、elephone links and are expected to remain for some time to come. However, new applications for those links in the fiied service are not expected to expand in these bands; s and UHF bands; that fiied and mobile applications for services ancillary to broadcasting are likely to be expanded in the VHF h
7、) that a variety of system characteristics exists for broadcasting, fixed and mobile service applications; j the broadcasting service and the fixed and mobile services, in particular concerning systems involving new technology, that studies are progressing in the Radiocommunication Sector (ITU-R) co
8、ncerning the compatibility between recommends 1. that frequency separation, geographical separation and time sharing, or a combination thereof, be used to ensure compatibility where sharing is required between different services. In this context, frequency sharing refers to the subdivision of the al
9、located bands between different services, geographical separation refers to the simultaneous use of a frequency by different services in separate geographical areas, and time sharing refers to the use of separate hours of operation for each of the services; 2. that the procedure in Annex 1 be used t
10、o determine the protection margin for the broadcasting service (sound and television) when it is operated simultaneously with either the fiied or land mobile service in shared or in adjacent VHF or UHF bands; 3. operated simultaneously with the broadcasting service in shared or in adjacent VHF or UH
11、F bands; that the procedure in Annex 2 be used to determine the protection margin for the land mobile service when it is * Radiocommunication Study Group 1 made editorial amendments to this Recommendation. 2 Rec. ITU-R SM.851-1 Band I (41-68 MHz) Field strength to be protected (dB(pV/m) at edge of c
12、overage area (50% of time, 90% of locations) 46 4. operated simultaneously with the broadcasting service in shared or in adjacent VHF or UHF bands; that the procedure in Annex 3 be used to determine the protection margin for the fixed service when it is Band II (76-100 MHz) 48 5. that the system par
13、ameters related to determination of these protection margins include: minimum field strengths to be protected, protection ratios, antenna characteristics, propagation conditions and other related factors as described in Annexes 1 , 2 and 3; 6. and 3; that the parameters contained in this Recommendat
14、ion be used only for systems referred to in Annexes 1, 2 7. that with the introduction of new technology (e.g. digital television, digital audio broadcasting, digital mobile and digital fixed) these parameters should be extended to accommodate future developments and to take account of ongoing Radio
15、communication Sector (ITU-R) studies. ANNEX 1 Protection of the broadcasting service from the fixed and land mobile services PART I TO ANNEX 1 Television services 1. Minimum field strength to be protected Table 1 gives the minimum field strength values to be protected at 10 m above ground level for
16、the broadcasting service (television) and the wanted field strength values fiom which they are derived. TABLE 1 Wanted field strength (dB(pV/m) at edge of coverage area (50% of time, 1 48 1 52 50% of locations) ftom Recommendation ITU-R BT.417 Band III (162-230 MHz) 49 55 Band IV (470-582 MHz) 53 65
17、 Band V (582-960 MHz) 58 70 The field strength to be protected is derived fiom the wanted field strength by taking account of the need to protect 90% of locations and the relatively high man-made noise levels in the VHF bands. Rec. ITU-R SM.851-1 3 Wanted field strength and field strength to be prot
18、ected ( these are dealt with separately below. Four distinct cases of interference to a station of the television service fi-om stations of the fixed or land mobile Rec. ITU-R SM.851-1 13 4.1.1 Interference from stations of the fixed service or base stations of the land mobile service which are orth
19、ogonally polarized with respect to a station of the television service In this case, the adjustment factor is equal to the antenna discrimination which has a value of -16 dB for 50% of locations and - 1 O dB for 90% of locations. 4.1.2 Interference from stations of the fixed service or base stations
20、 of the land mobile service which have the same polarization as a station of the television service In this case, the adjustment factor is equal to the relevant receiving antenna directivity discrimination value given in Recommendation ITU-R BT.419. For television Band II, the values as given for Ba
21、nd I should be used. 4.1.3 Interference from a land mobile station operating at more than 40 km outside the coverage area of a station of the television service No polarization discrimination can be taken into account because: the mobile transmitter system, consisting of an antenna and the body of a
22、 vehicle, cannot be assumed to radiate with only horizontal or vertical polarization; the effect of environmental clutter near the mobile transmitter can be expected to introduce a degree of depolarization. It would be impracticable to carry out calculations for all possible geographical locations f
23、or any mobile station, taking account of propagation losses and receiving antenna directivity discrimination. A reasonable simplification of the problem is to carry out interference calculations for the e.r.p. of the mobile station assuming this to be situated at the base station site with an effect
24、ive antenna height of 75 m. It is then appropriate to use an adjustment factor of -15 dB (see Note 1) to allow for the effect of clutter loss and ground reflection effects near the mobile station. In some cases, it may be possible to include an additional adjustment to allow for the directivity of t
25、he television receiving antenna, as given in Recommendation ITU-R BT.419. For television in Band II, the values given for Band I should be used. Note 1 - See Final Acts of the Second Session of the Regional Administrative Conference for the planning of VHF/HF Television Broadcasting in the AEcan Bro
26、adcasting Area and Neighbouring Countries (RARC AFBC(2). 4.1.4 Interference from a land mobile station operating less than 40 km from a receiving site of a station of the television service In this case, it is necessary to carry out detailed calculations for individual, worst-case paths. No polariza
27、tion discrimination can be taken into account, for the same reasons as are explained in 5 4.1.3 above. 4.2 Multiple interference from Co-sited sources The interference arising from multiple Co-sited sources should be combined by means of the power-sum method: - E = lo log 1oO i= 1 where: Ei : value
28、(dB(pV/m), of (NF + AF) for each individual Co-sited source. As indicated in 5 3 above, NF is expressed in dB(pV/m) and AF in dB n : number of Co-sited sources E : effective interference (dB(pV/m). Note 1 - The value of E represents one of the terms to be included in the procedure given in 5 4.3 bel
29、ow. 14 Rec. ITU-R SM.851-1 4.3 Multiple interference from non co-sited sources The interference arising from multiple non co-sited sources should be combined by using the simplified multiplication method given in Annex II of the Final Acts of the RARCAFBC(2), 1989, reproduced herein as Appendix 1 to
30、 Annex 1. 4.4 Effective transmitting antenna heights The effective transmitting antenna height is determined according to Recommendation ITU-R PN.370. When the effective transmitting antenna height is less than 37.5 m or more than 1200 m, the field-strength values are calculated using the method des
31、cribed in the Final Acts of the RARCAFBC(2), reproduced herein as Appendix 2 to Annex 1. 5. Interference assessments Interference assessments should normally be made for several reception points within the service area of the television transmitter. These points should be those which are considered
32、to be most likely to suffer from interference. Moreover, for rebroadcasting stations, it is necessary to ensure that the received television signal is also protected against interference. In this case, the protection ratios given in Recommendation ITU-R BT.655 for the limit of perceptibility are nor
33、mally used. PART II TO ANNEX 1 Sound broadcasting services 1. Minimum field strengths to be protected The minimum values of field strength which require protection from the fixed and mobile service as given in 37 dB(pV/m) at an antenna height of 10 m above ground for monophonic reception 48 dB(pV/m)
34、 at an antenna height of 10 m above ground for stereophonic reception. Recommendation ITU-R BS.412, are: 2. Protection ratios The protection ratios for a wanted FM sound broadcasting station and an unwanted AM or FM fiied or mobile station are given in Figs. 8 and 9, and Tables 12 and 13 (for a maxi
35、mum frequency deviation of I75 and I50 kHz respectively). In the case of a very narrow-band FM interfering system, some relaxation may be possible (see also Report ITU-R SM.659). Rec. ITU-R SM.851-1 FIGURE 8 Radio-frequency protection ratios required by broadcasting services in band 8 (VHF) at frequ
36、encies between 87.5 MHz and 108 MHz using a maximum frequency deviation off 75 kHz 15 60 50 40 30 20 10 O -1 o -20 O 1 O0 200 300 400 Difference between the wanted and interfering carrier frequencies (kHz) Curves M1: monophonic broadcasting; steady interference M2: monophonic broadcasting; troposphe
37、ric interference S1: stereophonic broadcasting; steady interference S2: stereophonic broadcasting; tropospheric interference (protection for 99% of the time) (protection for 99% of the time) - Estimated values for AM interfering stations DI0 16 Rec. ITU-R SM.851-1 60 50 40 30 20 10 O -1 o -20 O FIGU
38、RE 9 Radio-frequency protection ratios required by broadcasting services in band 8 (VHF) using a maximum frequency deviation off 50 kHz 1 O0 200 300 400 Difference between the wanted and interfering carrier frequencies (kHz) Curves M1: monophonic broadcasting; steady interference M2: monophonic broa
39、dcasting; tropospheric interference (protection for 99% of the time) S 1: stereophonic broadcasting; steady interference S2: stereophonic broadcasting; tropospheric interference (protection for 99% of the time) The values of curves S1 and S2 apply equally to the pilot-tone system and the polar-modul
40、ation system - Estimated values for AM interfering stations 17 O 25 50 75 1 O0 125 150 175 200 225 250 275 300 325 350 375 400 Rec. ITU-R SM.851-1 TABLE 12 Protection ratios required by broadcasting services in band 8 (VHF) using a maximum frequency deviation of f 75 kHz Protection ratio (a) 39.0 32
41、.0 24.0 15.0 12.0 7.5 6.0 2.0 -2.5 -3.5 -6.0 -7.5 -10.0 -12.0 -15.0 -17.5 -20.0 Frequency spacing ocHz1 Monophonic Stereophonic Steady interference Tropospheric interference Steady interference Tropospheric interference FM AM FM AM FM AM FM AM O 25 50 75 1 O0 125 150 175 200 225 250 275 300 325 350
42、375 400 36.0 31.0 24.0 16.0 12.0 9.5 8.0 7.0 6.0 4.5 2.0 -2.0 -7.0 -11.5 -15.0 -17.5 -20.0 36.0 31.0 24.0 16.0 12.0 9.5 8.0 7.0 6.0 4.5 2.0 -2.0 -7.0 -7.0 -7.0 -7.0 -7.0 28.0 27.0 22.0 16.0 12.0 9.5 8.0 7.0 6.0 4.5 2.0 -2.0 -7.0 -11.5 -15.0 -17.5 -20.0 28.0 27.0 22.0 16.0 12.0 9.5 8.0 7.0 6.0 4.5 2.
43、0 -2.0 -7.0 -7.0 -7.0 -7.0 -7.0 45.0 51.0 51.0 45.0 33.0 24.5 18.0 11.0 7.0 4.5 2.0 -2.0 -7.0 -11.5 -15.0 -17.5 -20.0 45.0 51.0 51.0 45.0 33.0 24.5 18.0 11.0 7.0 4.5 2.0 -2.0 -7.0 -7.0 -7.0 -7.0 -7.0 37.0 43.0 43.0 37.0 25.0 18.0 14.0 10.0 7.0 4.5 2.0 -2.0 -7.0 -11.5 -15.0 -17.5 -20.0 37.0 43.0 43.0
44、 37.0 25.0 18.0 14.0 10.0 7.0 4.5 2.0 -2.0 -7.0 -7.0 -7.0 -7.0 -7.0 TABLE 13 Protection ratios required by broadcasting services in band 8 (VHF) using a maximum frequency deviation of f 50 kHz Protection ratio (a) I Stereophonic Frequency spacing ocHz1 Tropospheric interference Steady interference T
45、ropospheric interference I FM AM FM AM FM I AM FM AM 39.0 32.0 24.0 15.0 12.0 7.5 6.0 2.0 -2.5 -3.5 -6.0 -7.5 -10.0 -10.0 -10.0 -10.0 -10.0 32.0 28.0 22.0 15.0 12.0 7.5 6.0 2.0 -2.5 -3.5 -6.0 -7.5 -10.0 -12.0 -15.0 -17.5 -20.0 32.0 28.0 22.0 15.0 12.0 7.5 6.0 2.0 -2.5 -3.5 -6.0 -7.5 -10.0 -10.0 -10.
46、0 -10.0 -10.0 49.0 53.0 51.0 45.0 33.0 25.0 18.0 12.0 7.0 5.0 2.0 0.0 -7.0 -10.0 -15.0 -17.5 -20.0 49.0 53.0 51.0 45.0 33.0 25.0 18.0 12.0 7.0 5.0 2.0 0.0 -7.0 -7.0 -7.0 -7.0 -7.0 41.0 45.0 43.0 37.0 25.0 18.0 14.0 11.0 7.0 5.0 2.0 0.0 -7.0 -10.0 -15.0 -17.5 -20.0 41.0 45.0 43.0 37.0 25.0 18.0 14.0
47、11.0 7.0 5.0 2.0 0.0 -7.0 -7.0 -7.0 -7.0 -7.0 18 Rec. ITU-R SM.851-1 3. Protection margin for sound broadcasting services The protection margin (PM) is given (dB) by: PM = FS - combined value of (NF + AF) for all interfering sources where: FS : AF : NF : relevant field-strength value (dB(pV/m) given
48、 in 5 1 above adjustment factor (a), intended to deal with antenna discrimination and clutter loss (see 5 4.1 below) nuisance field and the larger of Ec and ET given below (dB(pV/m). For continuous interference: EC = E(50,50) AC For tropospheric interference: ET = E(50,t) + + AT where: E(50,t) : fie
49、ld strength (dB(pV/m) of the interfering transmitter, normalized to 1 kW, and exceeded during to? of the time, determined using Recommendation ITU-R PN.370. For tropospheric interference the value oft is between 1 and 10 (the precise value should be specified by each administration) e.r.p. ( which might cause interference in relation to the required protection ratio (Ai). For the n interfering transmitters identified, the resulting nuisance field, Est, is: Eni(50, T) : Pi Ai protection ratio (dB); Bi receiving antenna discrimination (dB). field strength in dB(pV/m) of the
