ITU-R BT 472-3-1990 Video-Frequency Characteristics of a Television System to Be Used for the International Exchange of Programmes between Countries That Have Adopted 625-Line Colorol .pdf

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1、CCIR VOLUflE*XI-L 90 4855232 0504434 3 Previous page is blank Rec. 412-3 43 SECTION 11 C: CONTROL, MEASUREMENT AND INTERNATIONAL EXCHANGE OF TELEVISION PROGRAMMES RECOMMENDATION 472-3 * VIDEO-FREQUENCY CHARACTERISTICS OF A TELEVISION SYSTEM TO BE USED FOR THE INTERNATIONAL EXCHANGE OF PROGRAMMES BET

2、WEEN COUNTRIES THAT HAVE ADOPTED 625-LINE COLOUR OR MONOCHROME SYSTEMS (Questions 1/11, 2/11) (1970- 1974- 1986- 1990) The CCIR UNANIMOUSLY RECOMMENDS 1. the video characteristics, given below, for the international exchange of programmes between countries that have adopted 625-line colour or monoch

3、rome television systems. In particular, countries that use Systems B, C, D, G, H, I, K, K1 and L will facilitate programme interchange by adopting these characteristics. Note I - The details concerning the linelblanking and field-blanking intervals are listed in the same order and are designated by

4、the same symbols as in Report 624. Note 2 - This Recommendation is not intended to apply to Standard N. 2. General characteristics 2.1 2.2 2.3 2i4 2.5 2.6 2.7 2.8 2.9 2.10 Number of lines per picture: Line frequency and tolerance fH (Hz) c) - monochrome transmissions: - colour transmissions: Field f

5、requency fy (Hz): Picture-frame frequency fp (Hz): Gamma of picture signal: Nominal video bandwidth (MHz): Nominal difference between black level and blanking level (as a percen- tage of the luminance amplitude): Nominal video level at interfaces (from synchronizing level to peak white-level) (V,):

6、Nominal video level at interfaces (from blanking level to peak white- level) ( Vpp): Nominal synchronizing level at interfaces (from blanking level to synchronizing level) ( GP): . 625 15625 f 0.02% 15 625 f 0.0001% (21625) fH (11625) f approx. 0.4 5, or 5.5, or 6 (*) +5 0-0 1.0 (3) 0.7 (3) 0.3 (3)

7、3. Details of line-blanking interval (“ (Pd (H) Nominal duration of a line: (u) Line-blanking interval: (b) Interval between datum (OH) and back edge of line-blanking signal (average (c) Front porch: 1.5 +- 0.3 () (d) Synchronizing pulse: (e) Build-up time (10-90%) of line blanking edges: H = 64 12

8、f 0.3 () calculated value or information): 10.5 4.7 f 0.2 0.3 f 0.1 0.2 f 0.1 (f) Build-up time (10-90%) of line-synchronizing pulses: * This Recommendation should be brought to the attention of Study Groups 4 and 9 and the CMTT. CCIR VOLUME*XI-1 90 W 4855232 0504435 5 W I 44 Rec, 472-3 4. Details o

9、f the field-blankiag interval (j) Field-blanking period: (k) Build-up time (10-90%) of field-blanking edges as in (e): () Duration of first equalizing pulse sequence: (m) .Duration of field-synchronizing pulse sequence: 25 H f u (6) 0.3 f 0.1 2.5 H, or 3 H() 2.5 H, or 3 Duration of second equalizing

10、 pulse sequence: Duration of equalizing pulse (one half the value given in (d): Duration of field-synchronizing pulse (average calculated value for informa- tion): 27.3 - 2.5 H, or 3 H(3 2.35 zk 0.1 Interval between field-synchronizing pulses as in (d) : 4.7 f 0.2 Build-up time (10-90%) of field-syn

11、chronizing pulses as in (f): 0.2 f 0.1 When the reference of synchronism is being changed, the tolerance for colour transmissions may be increased to f 0.01% (see Report 624). Attention is drawn to the desirability of adding to these characteristics a value for the maximum rate of change of line fre

12、quency. The attention of Study Groups 4 and 9 and the CMTT is drawn to the desirability of subsequently standardizing tolerances for corresponding transmission characteristics applicable to all 625-line systems. For international routine measurements, it is suggested that the- test signals be based

13、on a single reference frequency which could be 5 MHz, particularly by countries using systems with nominal video bandwidth of 6 MHz. For example, this suggestion is not contrary to the use of a frequency close to 6 MHz in a multiburst test signal. When the voltage is measured across a matched 75 fi

14、termination. The nominal value of the picture-synchronizing signal ratio is 7/3. For details of permitted tolerances in long-distance transmissions, see Recommendation 567. In 625-line countries using teletext system B as specified in Annex I to Recommendation 653, to reduce the possibilities of dat

15、a loss, the following values are preferred CCIR, 1982-86aY b: (a) line-blanking interval: 12:;: ps (c) front porch: 1.5:;:; ps In the blanking interval, lines 16, 17, 18, 19, 20, 21 and 329, 330, 331, 332, 333 and 334 are reserved for the reception of any special signals. These. values may be subject to revision in the case where a single equalizing pulse system might be adopted (see CCIR, 1963-661 and Report 626). REFERENCES CCIR Documents 1963-661: XI/115 (United Kingdom). 1982-861: a. 11/365 (Australia); b. 11/376 (Germany (Federal Republic of).