1、CCIR RECMN*792 92 m 4855232 O520009 373 m I The CCIR, 140 Rec. 792 RECOMMENDATION 792* INTERFERENCE PROTECTION RATIOS FOR THE IN THE 12GHz BAND (Questions 83/11, 87/11, 88/11 and91/11) BROADCASTING-SATELLITE SERVICE (TELEVISION) ( 1992) considering a) that the interference protection ratio is a prim
2、ary parameter for the broadcasting-satellite service CBSS) (television); b that certain values of protection ratios for television signals have already been used for planning purposes by the WARC-BS-77 and RARC SAT-83; c) that more accurate values of protection ratio required for frequency modulated
3、 television systems, using time domain multiplex for the video components, and digital techniques for associated sound and data, are now well established; 4 that the existing Plans for the BSS in the 12 GHz band may be reconsidered in the future and that the planning will require protection ratio da
4、ta for the types of wanted and interfering signals involved; e) that the selectivity characteristics of receiving equipment for the BSS (television) are designed Ling into account these values, recommends 1. systems using conventional frequency modulated TV signals; that the protection ratio templat
5、es given in Annex 1 should be used for the planning of broadcasting-satellite 2. that for satellite broadcasting using conventional frequency modulated TV and the channel spacings specified in Appendix 30 of the Radio Regulations, but with a different frequency deviation, the formulae given in Annex
6、 2 could be used to obtain an estimation of the Co-channel protection ratio PRO measured under the reference conditions described in Recommendation 600. In these formulae, it is assumed that the modulation parameters of the wanted and unwanted signais are the same; 3. that to facilitate the coordina
7、tion of MAC systems in the 12 GHz band, the values shown in Table 1 2-MAC), Table 2 (D-MAC) and Tables 3,4 and 5 (B-MAC) of Annex 3 could be used as protection ratios. Note I - Data applicable to new systems (for example HDTV analogue or digital) are not yet available. but will be included in future
8、 revisions of this Recommendation. * Note from the Director, CUR - Report 634-4 was used in preparing this Recommendation CCIR RECflN*792 92 4855232 0520030 993 m Rec. 792 ANNEX1 141 Protection ratios for satellite broadcasting of conventional frequency modulated television signais 1. emphasis for 6
9、25 lines (Region 1) and 525 lines (Region 3), use Fig. la. 2. For systems SECAM, PAL and NTSC (Regions 1 and 3) with deviation sensitivity 13.5 MHz and pre- For system NTSC (Region 2) with deviation sensitivity 12 MHz, and pre-emphasis for 525 lines, use Fig. 1 b. FIGURE la Reference case protection
10、 ratios relative to co-channel values 10 O -1 o h 3 .g E c -20 .n Y 8 Ei 2 a d 2 -30 e O O -40 -5 O -30 -20 -1 o O 10 20 t 1 Carrier-frequency offset, Af (MHz) Af = (fnrerfering - hanred) CurvesA: notused B: television/frequency modulation-wanted, television/frequency modulation interfering, Co-chan
11、nel value: 30 dB (Regions 1 and 3) televisiodfrequency modulation-w anted, televisiodvestigial sideband modulation interfering, co-channel value: 30 dB (Regions 1,2 and 3) C: 30 CCIR RECMN*792 92 W LIB552312 0520055 B2T m 142 Rec, 792 FIGURE lb Protectlon ratlo template (FiM-TV) Region 2 Carrier fre
12、quency offset& (MHz) Protection ratio (peak-to-pcak frequency deviation D, = 12 MHz): -2.762 if01 + 51.09 dB for 8.36 c ifoi I 12.87MHz 28.0 di3 for If01 I 8.36MHz -1.154 if01 + 30.4 dB fml2.87 c If01 21.25 MHz ANNEX 2 Formulae for estimating co-channel protection ratios for conventlonal frequency m
13、odulated TV 1. For all systems except 525 line M/NTSC PRO = C - 2010g (Dv/12) - Q + 1.1 Q2 (la) where: Dy : nominal peak-to-peak frequency deviation (MHz) Q: the impairmetit grade, concerning the effect of interference only, measured on the 5-point scale recommended in Recommendation 500 C: a consta
14、nt depending on the television system which is: 12.5, for 625-line systems WAL, GPAL, L/SECAM 18.5, for 625-line system WSECAM. 2. For 525-line system MMTSC where: PRO = 16.9 - 8.7 log I, - 20 log (O,/ 12) Equation (lb) is based on data obtained from measurements carried out in Canada and the United
15、 States of America using 525-line system ?v/NTSC. This equation was found to provide a reasonably good fit to these data over the full range of Q. CCIR RECMN*2 92 - 4855232 0520012 766 I I Rec. 792 ANNEX 3 Protection ratios for MAC television signais I I TABLE 1 Protection ratios between D2-MAUpacke
16、t and PAUSECAM (WARC-BS-77) Wanted signal 143 Interfering signai Lower adjacent Upper adjacent Co-channel channel channel I I (dB) I I I C/I corresponding to the visibility threshold D2-MACIpacket (W ARC-B S -77) PAUSECAM D2-MACIpacket 20 11 12 D2-MAC/packet 27 12 13 Wanted signal (1) Interfering si
17、gnai (1) D-MAC/packet D-MAC/packet continuous data (2) D-MAClpacket C-MAUpacket (3) PAL system D-MAC/packet (W ARC-B S -77) continuous data (2) PAL system C-MAC/packet (3) Lower adjacent Upper adjacent channel channel Co-channel 17 3 1 27 10 6 22 7 6 29 11 8 Deviation sensitivity for all signals at
18、the cross-over frequency of the pre-emphasis network: 13.5 MHzN. RF channel bandwidth: 27 MHz. Pre-emphasis parameters for D2-MAC: A = 0.7071, fi = 0.84 MHz, f2 = 1.50 MHz. Note 1 -The values given in this table were measured with a -3 dB bandwidth of 27 MHz using a 5th order Chebyshev IF filter. TA
19、BLE 2 Protection ratios for the D-MAC/packet system using frequency modulation* 144 NTSC CCIR RECMN*772 92 48555E) 0520053 bTE! B-MAC Rec. 792 NTSC Wanted signai B-MAC TABLE 3 Co-channel intcrfcrence results for BMAC (CA (dB) MB = 24.3 CB = 26.1 MB = 24.4 CB 3 26.2 Average = 25.2 Average = 25.3 ME!
20、= 24.3 CB = 25.1 MB = 23.6 CB = 25.1 Average = 24.4 Average = 24.4 NTSC Wanted signai B-MAC Interfering signai B-MAC NTSC ME -4.3 C =4.4 MB 7.4 CB =7.2 Average = 4.3 Average = 7.3 MB=4.2 CB 2.4 MB = 6.1 CB = 6.8 Average = 3.3 Avcrage = 6.5 MB: multiburst video test signai CB: 75% colour bar test sig
21、nai NTSC TABLE 4 Upper adJacent-channel intcrfcrence results for B-MAC (C/ (dB) B-MAC Wanted signai - MB: multiburst video test signal CB: 75% colour bar test signai NTSC MR = 5.5 GI3 = 2.9 MB=7.2 CB =5.1 Average = 4.2 Average = 6.2 B-MAC m =5.7 CI3 = 3.9 MB =9.1 CB =9.2 Avcrage = 4.8 Average = 9.2 TABLE 5 Lower adjacent-channel lnterfercncc results fer B-MAC (C/ (dB) MR: multiburst video test signai CB: 75% colour bar test signal Pre-emphasis parameters for B-MAC A = 0.7071, fi = 1.87 MHz, f2= 3.74 MH2.
