1、 STD-SMPTE RP 87-ENGL 1999 W H3574d flC103Z11 TOT m SMPTE RECOMMENDED PRACTICE RP 87-1999 Revision of RP 87-1995 Reference Carrier Frequencies, Pre- emphasis Characteristic and Audio and Control Signals for 3/4-in Type E Helical- Scan Television Tape Cassette Recording 1 Scope This practice specifie
2、s the reference frequencies for deviation of the frequency modulated camer and as- sociated video preemphasis characteristic for 3/4-in type E helical-scan video tape cassette recording of 525-line monochrome and NTSC color television sig- nals at a tape speed of 95.3 mmls (3.752 ids). In addition,
3、the characteristics of the audio and control signals are specified. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this practice. At the time of publication, the editions indicated were valid. All standards are subjec
4、t to revision, and patties to agreements based on this practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. EIA RS-170, Electrical Performance Standards - Monochrome Television Studio Facilities EIA Industrial Electronics Tentat
5、ive Standard No. 1, Color Television Studio Picture Line Amplifier Output Drawing 3 Video signal 3.1 Luminance carrier frequencies 3.1.1 Reference white level: 5.4 MHz f 0.1 MHz 3.1.2 Reference sync level: 3.8 MHz 10.2 MHz 3.1.3 Reference white to sync level deviation: 1.6 MHz f 0.1 MHz Page 1 of 3
6、pages 3.2 Recording current characteristics 3.2.1 FM luminance carrier recording current shall be adjusted to produce maximum playback level. A high-pass filter having the characteristic shown in figure 1 shall be inserted into the FM signal path. Figure 1 - FM hig h-pass filter 3.29 The down-conver
7、ted chrominance signal of the AM chrominance carrier recording shall be 688.374 kHz f 0.200 kHz. The recording current shall be that at which the playback signal level is 10 dB to 14 dB below the peak luminance level of color bars at 75% color saturation. 3.3 Luminance signal preemphasis characteris
8、tics 3.3.1 The preemphasis is shown in figure 3 and defined as the impedance response to the four- terminal network in figure 2. 3.39 Preemphasis is introduced to the video sig- nal prior to the modulator. Copyright O 1999 by the SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Av
9、e., White Plains, NY 10607 (914)761-1100 Approved November 5,1999 STD-SMPTE RP 87-ENGL 1999 8357rlU1i UOO392i( 9lb 111 RP 87-1 999 4 Audio signal 4.1 Recording characteristics 4.1.1 High-frequency time constant of 50 ps 4.1.2 Low-frequency time constant of 3180 ps 4.2 Bias current With a sine-wave r
10、ecording signal of 1 kHz, the bias current shall be increased from the value producing maximum reproduced signal output to a level which resutts in the signal output dropping 0.5 dB. 4.3 Reproducer operating level The reproducing volume indicator (vu meter) shall deflect to the scale reference level
11、 (O dB) when play- ing back a tape recorded with a 1000 Hz sine-wave short-circuit tape flux per unit track width of 100 X= Rb/Ra= 2.5t 0.3 nWb/m. Figure 2 - Preemphasis network 0.040.05 0.07 0.1 0.2 0.3 0.4 0.5 0.7 1 2 3 456 Frequency (MHz) Figure 3 - Video preemphasis characteristic response for f
12、igure 2 Page 2 of 3 pages 852 PI RP 87-1999 5 Control signal 5.1 Polarity shall identify field 1 of the NTSC signal as defined by EIA RS-170 and EIA Industrial Electronics Tentative Standard No.1. The reference pulse shall be the posi- tive-going pulse as shown in figure 4. A positive-going pulse sh
13、all be obtained at the plus terminal of the control-track head on playback where there is a change from south to north in the polarity of the magnetic tape. A south to north polarity change 5.2 Recording current waveform The rise time shall be leSS than 200 PS- Field sync pulse _c tcadfng edges of field sync signals I I I Reproducing signal Minus Ti = 33.57ms Polarity = Plus, north; minus, south Figure 4 - Control signals waveform and polarity Annex A (informative) Bibliography ANCIICMPTE 21M-1997, Video Recording - 3/4-in Type E Helical Scan - Records Page 3 of 3 pages
