1、CCIR RECMN*:804 92 I 4855232 0520309 052 130 Rec. 804 RECOMMENDATION 804* CHARACTERISTICS OF TV RECEIVERS ESSENTUL FOR FREQUENCY PLANNING WITH PAUSECAM/NTSC TELEVISION SYSTEMS (Question 26/1 i) _ ( 1992) The CCIR, considering a) that conventional television systems bave been in use for a long period
2、 of time; b) that the characteristics of television receivers, essential for frequency planning, are well establisbed for the various PAL/SECAM/NTSC television systems; C) that those characteristics continue to be upgraded; d) that characteristics referred to in 4 c) bave been the basis for planning
3、 parameters and methods used for the Second Session of the Regional Administrative Conference for the planning of VHF/UHF television broadcasting in the African Broadcasting Area and Neighbouring Countries (AFBC(2); e) f) definitions, that conventional television systems will remain in use for a con
4、siderable period of time; that the IEC has responsibilities relating to television receiver standards and methods of measurement and recommends that the characteristics of television receivers given in Annex 1 be employed as a basis for frequency that the characteristics given in Annex 2 be regarded
5、 as information on the performance characteristics of 1. planning; 2. receivers in use, by some administrations. Other administrations are urged to provide similar information. ANNEX 1 Television receiver characteristics 1. introduction Many characteristics of television receivers may be defined, to
6、gether with methods of measurement and These characteristics are tabulated in 2 in which it is suggested that the most recent mean numerical values The quality of the picture displayed and of the sound heard depends on characteristics of the complete Characteristics essential for planning are given
7、in Tables 1 to 3 together with typical values in current use for practical values. should be included. television system from the studio to the receiver screen or loudspeaker. the various television systems. * This Recommendation should be brought to the atteotioo of the EC. CCIR RECflN*804 92 I 485
8、5232 0520330 874 = No. of lines Country in system 525 USA 525 Japan Spain, Norway, Netherlands, Federal Republic of Germany, Sweden, Switzerland, Italy, Yugoslavia Rec. 804 131 Channel limits at frequency (MHz) System (1) intermediate M 41 to 47 (3) M 54 to 60 (4) (5) 33.15 to 40.15 B, G Attention i
9、s drawn to the importance of effective participation by CCIR representatives in LEC work, especially in the field of definitions and methods of measurement of television receiver characteristics (Sub-committee 12A). This information is important for planning and for achieving satisfactory quality ta
10、rgets in an overall television system, from picture source up to and including the receiver. to the relevant CISPR Recommendations. Apart from these characteristics, those relating to interference caused by television receivers should conform 2. Intermediate frequencies for television receivers Soun
11、d-channel TABLE 1 Examples of current systems intermediate frequency values Video-channel 39.20 (6) The Russian Federation 31.25 to 39.25 625 Peoples Republic of China 32.70 (6) France UK African broadcasting area L 31.00 to 39.50 I 33.25 to 41.25 K1 33.45 to 41.45 33.15 to 40.15 31 .O0 to 39.50 41.
12、25 1 45.75 54.25 1 58.75 3 1.50 38.00 33.50 I 39.50 33.70 33.40 39.20 40.20 39.90 32.70 (1) See Recommendation 470. (2) (3) (4) Protected bands. (5) (6) The usual position of the local oscillator is high. In those cases where it is low, the vision intermediate frequency is below the sound intermedia
13、te frequency. According to Electronic Industries Association Standard Recommendation No. 109 C Television receivers, ali channels (VHF and UHF). According to Recommendation No. 103 of the Syndicat des constnicteurs dappareils radiorcepteurs et tlviseurs SCARTJ. In Band I, a double transposition is u
14、sed. The multiplicity of values of the intermediate frequency is a cause of increased cost of receivers, particularly Reception of television programmes with different standards may require adequate values of the intermediate those suitable for frontier regions where countries use standards with dif
15、ferent radio frequencies. frequency involving the same number of multi-standard receiver types. CCIR RECflN*fiO4 92 M 4855212 0520555 700 M 132 Rec. 804 2.1 Reference receiver characteristics In order to obtain the protection ratios given in Recommendation 655, the minimum field-strength values give
16、n in Recommendation 417, ?nd meet other frequency planning constraints, the values given in Table 2 for reference receivers for different transmission systems should be met. As receiver technology is improving rapidly, administrations are invitcd to study any improvement of the planning parcmeters w
17、hich can result from improved receiver characteristics. TABLE 2 Reference receiver charscterlstics Itch Characteristics - Noise-limited sensitivity (dBm) Rejection of adjacent picture carrier (I IVN 12 GHz High High uning tolerance (kHz1 Broadcasting band I III IVN 12 GHz 8 f loo f loo f loo f 350 f
18、 350) (4) f 358 f 58 (5) 9 Receiver radiation Broadcasting band I III IVN 12 GHz Susceptibility of receiver to external interference Broadcasting band I 10 III IVN 12 GHz a CCIR RECMN*i!04 92 4855212 0520134 41T ! I1 Rec. 804 TABLE 4 (confinued) I I I Intermediate frequency values Broadcasting band
19、I IVN AI 12 GHz Item Publication IEC 107- 1 Definition Measuring Presentation method of results Clause 105 and Clause I10 For a peak-to- Clause 109 peak luminance signal-to-non- weighted noise ratio of 30 dB Characteristic Remarks The most unfavour- able value for each of the broadcasting bands I t
20、Item I 2 Characteristic Noise-limited sensitivity Protection ratios Country United Rejection of adjacent picture carrier Rejection of adjacent sound carrier See See Table 1 Table I Clause 136 Clause 137 Clause i38 Clause 136 Clause 137 Clause 138 I image-frequency rejection In termediate-frequency r
21、ejection Russian Federation Clause 146 Clause 147 Clause 138 Clause 144 Clause 145 Clause 138 See Table 1 7 8 9 10 (1) The following characteristics relate to System I colour television receivers (2) For a luminance signal-to-unweighted noise ratio of 30 dB and a normalized output level (3) For a lu
22、minance signal-to-unweighted noise ratio of 20 dB and a normalized output level. Oscillator position High or iow Tuning tolerance Clause 47 Clause 48 Clause 5 1 As a function of time Receiver radiation Susceptibility of receiver Under study Interference not to external interference As specified in C
23、ISPR Recommendation No. 24/2 entering by the antenna (4) The tuning tolerance must be reduced to f 50 kHz if the television set is provided with a Teletext decoder. This tuning tolerance is achievable using an automatic frequency control or a frequency synthesizer. (5) With automatic frequency control. TABLE 5 List of characteristics (from relevant IEC and CISPR documents) 135 The most unfavour- able value for each of the broadcasting bands I Intermediate-frequency I I values See Table 4 I
