ITU-R BS 412-9-1998 Planning Standards for Terrestrial FM Sound Broadcasting at VHF《VHF地面调频声音广播的规划标准》.pdf

1、 Rec. ITU-R BS.412-9 1 RECOMMENDATION ITU-R BS.412-9*Planning standards for terrestrial FM sound broadcasting at VHF (1956-1959-1963-1974-1978-1982-1986-1990-1994-1995-1998) The ITU Radiocommunication Assembly, recommends that the following planning standards should be used for frequency modulation

2、sound broadcasting in band 8 (VHF): 1 Minimum usable field strength 1.1 In the presence of interference from industrial and domestic equipment (for limits of radiation from such equipments refer to Recommendation ITU-R SM.433, which gives the relevant CISPR recommendations) a satisfactory service re

3、quires a median field strength (measured at 10 m above ground level) not lower than those given in Table 1: TABLE 1 1.2 In the absence of interference from industrial and domestic equipment, the field strength values (measured at 10 m above ground level) given in Table 2 can be considered to give an

4、 ac-ceptable monophonic or stereophonic service, respectively. These field strength values apply when an outdoor antenna is used for monophonic reception, or a directional antenna with appreciable gain for stereophonic reception (pilot-tone system, as defined in Recommendation ITU-R BS.450). TABLE 2

5、 NOTE 1 The figures of Table 2 are not median values and, consequently, they are not directly comparable with those given in Table 1. _ *Radiocommunication Study Group 6 made editorial amendments to this Recommendation in 2002 in accordance with Resolution ITU-R 44. Services Areas Monophonic dB(V/m)

6、 Stereophonic dB(V/m) Rural 48 54 Urban 60 66 Large cities 70 74 Services Monophonic dB(V/m) Stereophonic dB(V/m) 34 48 2 Rec. ITU-R BS.412-9 1.3 In a practical plan, because of interferences from other sound broadcasting transmissions, the field strength values that can be protected will generally

7、be higher than those of Table 1. Moreover, in the case of the boundary area between any two countries, the exact values to be used should be agreed between the administrations concerned. 2 Radio-frequency protection ratios 2.1 General 2.1.1 The Radio-Frequency (RF) protection ratio is the minimum va

8、lue of wanted-to-unwanted signal ratio, usually expressed in decibels at the receiver input, determined under specified conditions such that a specific reception quality is achieved at the receiver output. The protection ratio curves were originally determined by subjective evaluation of interferenc

9、e effects. As subjective tests are rather time-consuming an objective measuring method was deve-loped (see Annex 1 to Recommendation ITU-R BS.641) and found to yield results which are in fair agreement with those of the subjective tests. 2.1.2 Except where otherwise stated, the values of protection

10、ratio quoted apply to interference produced by a single source. In the case of multiple interferences, appropriate assessment methods are indicated in Report ITU-R BS.945. 2.1.3 It is assumed that wanted and unwanted signals contain different programmes without any correlation. In the case of an ide

11、ntical programme (same modulation), an improvement of the protection ratio is expected at least for monophonic signals. 2.1.4 In the case of same frequency and same modulation, with synchronized signals, the protection ratios for monophonic signals are much lower than those in Fig.1. In the case of

12、stereo-phonic signals the protection ratios depend on the propagation delay and on the stereophonic con-tent (see Annex 3). 2.1.5 The protection ratio values are given for steady and tropospheric interference respectively. The protection ratios for steady interference provide approximately 50 dB sig

13、nal-to-noise ratio (weighted quasi-peak measurement according to Recommendation ITU-R BS.468, with a reference signal at maximum frequency deviation. See also Annex 1 to Recommendation ITU-R BS.641). The protection ratios for tropospheric interference correspond closely to a slightly annoying impair

14、-ment condition and it is considered acceptable only if the interference occurs for a small percentage of the time, not precisely defined but generally considered to be between 1 % and 10 %. In determining whether the interference is to be regarded as steady or tropospheric, see Annex 1. Significant

15、ly strong wanted signals can require higher protection ratio values than those given in Fig. 1 and Fig. 2, because of non-linear effects in the receiver (see Annex 2). 2.2 Monophonic service 2.2.1 The radio-frequency protection ratios required to give satisfactory monophonic reception, in systems us

16、ing a maximum frequency deviation of 75 kHz, for tropospheric interference, are those given by curve M2 in Fig. 1. For steady interference, it is desirable to provide a higher degree Rec. ITU-R BS.412-9 3 of protection, shown by the curve M1 in Fig. 1. The protection ratios at important values of th

17、e carrier frequency spacing are also given in Table 3. 0412-01 20 1001020304050604003002001000S1S2M1M2FIGURE 1Radio-frequency protection ratio required by broadcasting servicesin band 8 (VHF) at frequencies between 87.5 MHz and 108 MHzusing a maximum frequency deviation of 75 kHzRadio-frequency prot

18、ectionratios(dB)Difference between the carrier frequencies (kHz) of the unwanted and wanted signalsCurves M1: monophonic broadcasting; steady interferenceM2: monophonic broadcasting; tropospheric interferenceS1: stereophonic broadcasting; steady interferenceS2: stereophonic broadcasting; tropospheri

19、c interference2.2.2 The corresponding values for monophonic systems using a maximum frequency deviation of 50 kHz are those given by the curves M2 and M1 in Fig. 2. The protection ratios at important values of the carrier frequency spacing are also given in Table 4. 4 Rec. ITU-R BS.412-9 2.3 Stereop

20、honic service 2.3.1 The radio-frequency protection ratios required to give satisfactory stereophonic reception, for transmissions using the pilot-tone system and a maximum frequency deviation of 75 kHz, for tropospheric interference, are those given by curve S2 in Fig. 1. For steady interference it

21、is desirable to provide a higher degree of protection, shown by the curve S1 in Fig. 1. 0412-02400300200100 20 1001020304050600S1S2M1M2FIGURE 2Radio-frequency protection ratios required by broadcasting servicesin band 8 (VHF) using a maximum frequency deviation of 50 kHzRadio-frequency protectionrat

22、ios(dB)Difference between carrier frequencies (kHz) of the unwanted and wanted signalsCurves M1: monophonic broadcasting; steady interferenceM2: monophonic broadcasting; tropospheric interferenceS1: stereophonic broadcasting; steady interferenceS2: stereophonic broadcasting; tropospheric interferenc

23、eRec. ITU-R BS.412-9 5 The protection ratios at important values of the carrier frequency spacing, are also given in Table 3. 2.3.2 The corresponding values for stereophonic systems using a maximum frequency deviation of 50 kHz are those given by the curves S2 and S1 in Fig. 2. The protection ratios

24、 at important values of the carrier frequency spacing are also given in Table 4. TABLE 3 TABLE 4 Radio-frequency protection ratio (dB) using a maximum frequency deviation of 75 kHz Carrier frequency Monophonic Stereophonic spacing (kHz) Steady interference Tropospheric interference Steady interferen

25、ce Tropospheric interference 000 36.0 28.0 45.0 37.0 025 31.0 27.0 51.0 43.0 050 24.0 22.0 51.0 43.0 075 16.0 16.0 45.0 37.0 100 12.0 12.0 33.0 25.0 125 09.5 09.5 24.5 18.0 150 08.0 08.0 18.0 14.0 175 07.0 07.0 11.0 10.0 200 06.0 06.0 07.0 07.0 225 04.5 04.5 04.5 04.5 250 02.0 02.0 02.0 02.0 275 02.

26、0 02.0 02.0 02.0 300 07.0 07.0 07.0 07.0 325 11.5 11.5 11.5 11.5 350 15.0 15.0 15.0 15.0 375 17.5 17.5 17.5 17.5 400 20.0 20.0 20.0 20.0 Radio-frequency protection ratio (dB) using a maximum frequency deviation of 50 kHz Carrier frequency Monophonic Stereophonic spacing (kHz) Steady interference Tro

27、pospheric interference Steady interference Tropospheric interference 0 39.0 32.0 49.0 41.0 25 32.0 28.0 53.0 45.0 50 24.0 22.0 51.0 43.0 75 15.0 15.0 45.0 37.0 100 12.0 12.0 33.0 25.0 125 7.5 7.5 25.0 18.0 150 6.0 6.0 18.0 14.0 175 2.0 2.0 12.0 11.0 200 2.5 2.5 7.0 7.0 225 3.5 3.5 5.0 5.0 250 6.0 6.

28、0 2.0 2.0 275 7.5 7.5 0 0 300 10.0 10.0 7.0 7.0 325 12.0 12.0 10.0 10.0 350 15.0 15.0 15.0 15.0 375 17.5 17.5 17.5 17.5 400 20.0 20.0 20.0 20.0 6 Rec. ITU-R BS.412-9 2.4 Carrier frequency differences greater than 400 kHz The curves of Fig. 1 and Fig. 2 give protection ratio values for carrier freque

29、ncy differences between unwanted and wanted signals of up to 400 kHz. For carrier frequency differences greater than 400 kHz, the protection ratio values should be substantially lower than 20 dB. Detailed information on this subject is given in Annex 2. The radio-frequency protection ratio value for

30、 the particular carrier frequency difference of 10.7 MHz (intermediate frequency) should be below 20 dB. 2.5 Technical conditions 2.5.1 For the radio-frequency protection ratios given in Fig. 1 and Table 3, it is assumed that the maximum peak deviation of 75 kHz is not exceeded. Moreover, it is assu

31、med that the power of the complete multiplex signal (including pilot-tone and additional signals) integrated over any interval of 60 s is not higher than the power of a multiplex signal containing a single sinusoidal tone which causes a peak deviation of 19 kHz. It is important that the limits for m

32、odulation levels given above should not be exceeded, otherwise the radiated power of the transmitter has to be reduced in accordance with the increased figures for protection ratios given in Annex 2. Examples of measurement results, showing the maximum peak deviation and the power of the complete mu

33、ltiplex signal as a function of time are given in Annex 4. NOTE The power of a sinusoidal tone causing a peak deviation of 19 kHz is equal to the power of the coloured noise modulation signal according to Recommendation ITU-R BS.641, i.e. a coloured noise signal causing a quasi-peak deviation of 32

34、kHz. 2.5.2 The protection ratios for stereophonic broadcasting assume the use of a lowpass filter following the frequency modulation demodulator in the receiver designed to reduce interference and noise at frequencies greater than 53 kHz in the pilot-tone system and greater than 46.25 kHz in the pol

35、ar-modulation system. Without such a filter or an equivalent arrangement in the receiver, the protection ratio curves for stereophonic broadcasting cannot be met, and significant interference from transmissions in adjacent or nearby channels is possible. In determining the characteristics of the fil

36、ters whose phase response is important in the preser-vation of channel separation at high audio frequencies, reference should be made to Annex III of Recommendation ITU-R BS.644. 2.5.3 In the case of AM-FM receivers, it is necessary to take measures so that the circuits at the AM intermediate freque

37、ncy (generally 450-470 kHz) do not worsen the protection ratios when the receiver is operating in FM, particularly for differences between the frequencies of the wanted and interfering carrier greater than 300 kHz. 2.5.4 Data systems or other systems providing supplementary information, if introduce

38、d, should not cause more interference to monophonic and stereophonic services than is indicated by the protection ratio curves in Fig. 1. It is not considered practicable in the planning to provide additional protection to data services or other services providing supplementary information signals.

39、Rec. ITU-R BS.412-9 7 3 Channel spacing In frequency planning, channels are to be assigned in such a way that: 3.1 the carrier frequencies which define the nominal placement of the RF channels within the band are integral multiples of 100 kHz; 3.2 a uniform channel spacing of 100 kHz applies for bot

40、h monophonic and stereophonic transmissions. In those cases where a 100 kHz channel spacing would be difficult to implement, the use of a spacing which is an integral multiple of 100 kHz would also be acceptable, provided that the carrier frequencies are chosen in accordance with 3.1 above. ANNEX 1

41、Determination of whether the interference is to be regarded as steady or tropospheric To apply the protection ratio curves of Figs. 1 and 2 it is necessary to determine whether, in the particular circumstances, the interference is to be regarded as steady or tropospheric. A suitable criterion for th

42、is is provided by the concept of nuisance field which is the field strength of the interfering transmitter (at its pertinent e.r.p.) enlarged by the relevant protection ratio. Thus, the nuisance field for steady interference: Es= P + E (50, 50) + Asand the nuisance field for tropospheric interferenc

43、e: Et= P + E (50, T ) + Atwhere: P : e.r.p. (dB(1 kW) of the interfering transmitter A : radio-frequency protection ratio (dB) E (50, T ) : field strength (dB(V/m) of the interfering transmitter, normalized to 1 kW, and exceeded during T % of the time and where indices s and t indicate steady or tro

44、pospheric interference respectively. At the VHF/FM Conference, Geneva 1984, the percentage of time was chosen to be T = 1 %. The protection ratio curve for steady interference is applicable when the resulting nuisance field is stronger than that resulting from tropospheric interference, i.e. Es EtTh

45、is means that Asshould be used in all cases when: E (50,50) + As E (50, T ) + At8 Rec. ITU-R BS.412-9 ANNEX 2 Particular interference cases in FM broadcasting 1 Interference caused by an overmodulated transmitter Laboratory measurements were made in France to evaluate the sensitivity of several rece

46、ivers to interference in the case where the interfering transmitter is overmodulated. Interference was measured as described in Annex 1 to Recommendation ITU-R BS.641, for a stereophonic signal and a wanted RF receiver input level of 50 dB(mW) (0.7 mV/50 ). The 3 dB and 40 dB bandwidths of the RF fi

47、lter added at the output of the interfering transmitter were 500 kHz and 2 600 kHz respectively. Two overmodulation values were used: +3 dB and +6 dB. It was found that, for interfering signals within the receiver passband, the increase of protection ratios was not related to the type of receiver; t

48、hus, for a 100 kHz carrier frequency spacing, the increases in protection ratio were 11 dB and 15 dB for increases in modulation depth of 3 dB and 6 dB respectively. On the other hand, it was found that in the case of interference with a (non-standard) 150 kHz carrier frequency spacing, the change i

49、n protection ratios could be as high as 6 dB for a 1 dB change in modulation depth of the interfering transmitter. 2 Interference for large carrier frequency differences Tests to evaluate the effect of interference from transmissions having large frequency differences, which were carried out under similar conditions to those given in 1 above, were also made in France. In this case, measurements were made with normal modulation