BS-EN-60712-1996 IEC-60712-1993.pdf
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1、BRITISH STANDARD BS EN 60712:1996 IEC 712:1993 (Including amendment 1 May 1993 to IEC 712:1993) Helical-scan video-tape cassette system using 19 mm ( 26 dB attenuation between fc 0,5 MHz: 15 dB Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:29:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
2、 EN 60712:1994 BSI 01-200013 12.3.1 Characteristic frequencies for U-matic H-format are given below. Add the following new subclause: 12.3.2 Characteristic frequencies for SP-format The instantaneous frequencies corresponding to reference video levels shall be as indicated in the table below. The fr
3、equency deviation shall be 1,6 MHz 0,1 MHz. 12.4 Pre-emphasis The characteristics of the video pre-emphasis network are as follows: This also applies to SP-format 525/60. 12.4.1 For H-format and SP-format 625/50 the following values apply: TE= C Rb= 0,80 0,05 4s XE= Rb/Ra= 4,0 0,3 12.5 Recording fre
4、quency bandwidth The maximum recorded frequency of the luminance signal is: 12.5.1 Recording frequency bandwidth (H-format) The bandwidth of the recorded luminance signal is: 12.5.2 Recording frequency bandwidth (SP-format) For composite colour signals: 30 Hz 3,3 MHz ( 3 dB). 12.6 White clipping lev
5、el When the sync tip level is 0 % and the white peak level is 100 %, the white clipping level of the video signal shall lie between 135 % and 150 %. f1= sync tip frequency:4,8 (nom.) MHz f2= peak white frequency:6,4 0,1 MHz frequency deviation:1,6 0,1 MHz 625/50525/60 Reference video level Instantan
6、eous frequency Tolerance Instantaneous frequency Tolerance Sync tip Peak white 5,6 MHz (nom.) 7,2 MHz 0,1 MHz 5 MHz (nom.) 6,6 MHz 0,1 MHz for composite video signal (monochrome):4,2 MHz; for composite colour signal:3,5 MHz. for composite video signal (monochrome):4,2 MHz ( 3 dB) for composite colou
7、r signal:3,0 MHz ( 3 dB) Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:29:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60712:1994 14 BSI 01-2000 12.6.1 White clipping level after the pre-emphasis When the sync tip level is 0 % and the white peak level is 100 %, the white clipping lev
8、el of the video signal shall lie between 210 % and 230 %. 12.6.2 White clipping level after the pre-emphasis (SP-format) When the sync tip level is 0 % and the white peak level is 100 %, the white clipping level of the video signal shall lie as shown in the table below: 12.7 Non-linear pre-emphasis
9、(SP-format) The luminance signal shall receive non-linear pre-emphasis (see diagram below). The characteristics shall be as shown in Table 5 (625/50), and Table 6 (525/60). Block diagram of luminance non-linear pre-emphasis Table 5 Luminance non-linear pre-emphasis characteristics (625/50) Table 6 L
10、uminance non-linear pre-emphasis characteristics (525/60) 13 Audio signal channels Whenever a monophonic audio signal is recorded, it shall be recorded using either channel-2 (right) only, or both audio channels simultaneously. In audio dubbing, channel-1 (left) is recorded. 13.1 Audio recording cha
11、racteristic (See also IEC 94: Magnetic tape sound recording and reproducing systems.) The time constants shall be: 625/50525/60 225 % to 235 %165 % to 175 % Frequency MHz Input dB 3,0 2,0 1,00 0,5 1,0 1.5 2,0 3,0 3,5 5,9 6,5 6,2 3,9 2,5 3,8 4,0 3,8 2,6 1,2 1,8 2,0 1,9 1,2 0,4 0,6 0,7 0,7 0,5 Frequen
12、cy MHz Input dB 3,0 2,0 1,00 0,5 1,0 1,5 2,0 3,0 1,9 4,4 6,2 7,2 7,8 1,3 2,5 3,3 3,9 4,5 0,6 1,0 1,3 1,6 2,0 0,2 0,4 0,5 0,6 0,7 t1= 50 4st2= 3 180 4s Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:29:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60712:1994 BSI 01-200015 13.1.1 General
13、 All audio tracks are identical and shall be recorded using a.c. bias. 13.1.2 Phasing of the audio tracks (SP-format) When the same signal is recorded on the audio 1 and audio 2 tracks, the tracks shall be so phased that when reproduced with a head wide enough to respond to the recorded flux on both
14、 tracks, they will be additive. 13.1.3 Noise-reduction characteristics (SP-format) Noise reduction shall have the encoding characteristics shown in Table 7. 13.1.4 Noise-reduction pilot signal (SP-format) Pilot signal for automatic detection of noise reduction in reproducing audio signals is simulta
15、neously recorded in addition to audio signals of audio track using an audio head (see block diagram below). 13.1.4.1 Recording track: audio track 1,2 or both. 13.1.4.2 Recording frequency: Block diagram of noise-reduction pilot-signal recording 13.1.4.3 The recording phase shall be within 15 from tr
16、ailing edge of control signal 13.1.4.4 Recording level shall be 36 dB 3 dB below the recorded reference audio level, 100 nWb/m 10 nWb/m r.m.s. at 1 000 Hz, in reproducing with time constants of t1= 50 4s and t2= 3 180 4s. 13.1.4.5 The third harmonic distortion in reproducing with time constants of t
17、1= 50 4s and t2= 3 180 4s shall be less than 3 %. 13.1.4.6 The specifications of high-pass filter or band-elimination filter of the block diagram above shall be as follows: 625/50525/60 12,5 Hz Sine wave 15 Hz Sine wave 625/50525/60 12,5 Hz15 Hz Less than 20 dBLess than 20 dB Licensed Copy: sheffiel
18、dun sheffieldun, na, Sat Nov 11 09:29:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60712:1994 16 BSI 01-2000 Table 7 Audio frequency response of noise reduction Encoding level 13.2 Optimum audio bias current With a sine-wave signal of 1 kHz being recorded and played back, the signal output will
19、rise, reach a maximum, and then decrease, as the bias is increased. Bias current shall be set at the point where the signal output has gone beyond maximum and come down to a level 0,5 dB below maximum. 13.3 Use of the audio tracks 13.3.1 Monophonic programme sound signals shall be recorded on audio
20、track 2. 13.3.2 Audio track 1 may carry auxiliary sound at the users discretion. 13.3.3 In the case of stereophonic recording, audio track 1 shall carry the left channel and audio track 2 the right channel. 13.4 Recorded tape flux characteristics The recorded reference audio level shall correspond t
21、o a magnetic short-circuit flux level of 100 10 nWb/m r.m.s. at 1 000 Hz, if no pre-distortion is used. The programme peaks will normally be 9 dB above the reference level. Frequency Hz Level dB 0 10 20 30 40 50 60 100 200 300 500 1 k 3 k 5 k 10 k 15 k 0,2 0,1 0 0 0,3 1,6 2,3 3,5 6,3 0,9 1,5 1,6 1,7
22、 1,5 0,1 0,6 1,4 3,3 2,7 5,3 6,1 6,3 5,9 3,7 2,9 2,6 1,5 2,9 8,0 10,7 11,8 11,4 9,2 8,4 8,2 7,3 2,9 8,1 12,0 15,6 16,2 13,9 13,5 13,6 12,2 2,9 8,1 12,0 16,2 19,4 19,2 18,7 18,1 15,0 2,9 8,1 12,0 16,2 19,6 20,7 20,4 19,2 15,0 NOTE 1The input level of 0 dB is the reference audio input level at 1 000 H
23、z. NOTE 2The encode level of 0 dB is the recorded reference audio level specified in 13.4. NOTE 3A block diagram of encoding is shown below. NOTE 4The frequency response of the playback decoder shall be complementary to the record encoder. Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 09:29
24、:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60712:1994 BSI 01-200017 14 Control signal channel The repetition frequency (see table below) of the control signal on the control track is half the field frequency. NOTEDirect current shall be applied to the terminal of the head so as to make the he
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