1、CENELEC ENtb07L2 94 3404583 0171433 9T9 = BRITISH STANDARD Helical-scan video-tape cassette system using 19 mm (: in) magnetic tape, known as U-format The European Standard EN 60712 : 1994 has the status of a British Standard NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMIITED BY COPYRIGHT LAW 3s
2、EN i0712 : 1996 EC 712 : 1993 Including amendmeni 1 lay 1999 to IEC 712 : 1993) CENELEC EN*b07L2 94 m 3404583 OL7L434 835 m BS EN 60712 : 1996 This British Standard, having been prepared under the direction of the Electmtechnical Sector Board, was published under the authority of the Standards Board
3、 and comes into effect on 15 April 1996 O BSI 1996 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee ELP/GO, Recording, upon which the following bodies were represented Association of professional Recording Services Limited
4、 Audio Engineering Society British Broadcastjng Corporation British Kinematograph, Sound and Television Society British Tape Industry Association Federation of the Electronics Industry ITVAssociation TVA) National Councii for Educational Technology (NCET) Royal Photographic Society byal Television S
5、ociety Amendments issued since publication Amd.No. ID relative humidity: 48 %to 52 Y; air pressure: conditioning before testing: 24 h. 86 kPa to 106 kPa; CENELEC ENxb07I12 94 m 3404583 0171442 901 m Page 6 EN 60712 : 1994 3.2 Operation environment The system shall operate under the following conditi
6、ons: temperature (in recorder): 3.3 Reference tape (SP-format) 15 OC to 50 OC; 45 %o to 75 %. relative humidity: Blank tape to be used for reference recordings may be purchased from the manufacturers listed in annex A. The electromagnetic compatibility parameters and their specifications should be s
7、pecified by the manufacturers and controlled accordingly. The model name is IEC U-matic SP-format reference tape. Electromagnetic compatibility parameters and their specifications are indicated in annex A. 3.4 Calibration tape The calibration tapes which satisfy the following requirements will be av
8、ailable for pur- chase from the manufacturers producing video tape recorders and players in accordance with this format specification. 3.4.1 Record locations and dimensions For the calibration tapes to be used for the purpose of calibrating the mechanical accuracy of recorder or player in accordance
9、 with this format specification, 50 Yo reduction in the tolerance shown in table 2, page 63 of IEC 712, should be applied to them in principle. If necessary, the record locations and dimensions can be specially modified for some calibration tapes in order to avoid some calibration errors or to help
10、some calibration work. 3.4.2 Calibration signals Two classes of signals may be recorded on the calibration tapes: a) Video Audio A series of conventional test signals: - Colour bars (75 %) - 1 kHz OVU - Gated sweep - 10 kHZ -lOVU - Pulse and bar - 40 HZ -2OVU - 1 kHZ -2OVU - 7 kHZ -2OVU - 10 kHZ -20
11、 VU - 15 kHZ -20 VU b) Special test signals developed by each manufacturer for product alignment. These signals are not universally applicable too the products from all manufacturers and will not be specified. CENELEC EN*b07L2 94 m 3404583 OL7Lqq3 848 m Page 7 EN 60712 : 1994 SECTION 2: VIDEO-TAPE C
12、ASSETTE 4 Mechanical parameters 4.1 Dimensions of cassette The dimensions necessary to permit interchangeability of cassettes shall be in accordance with figures 1 to 5 and la to 5a and table 1. 4.2 Tape path and guidance The tape path and guidance are given in figure 6. 4.3 Tape winding The magneti
13、c coating on the tape shall face out of the cassette. The direction of tape travel is from left to right when the coated side is facing the observer, Le from supply reel and outside on the take-up reel (see figure 6). 4.4 Label and window area The level and window area shall be in accordance with th
14、e dimensions given in figures 1 and la. The label as well as the window shall not protrude beyond the surface of plane A in figures 1 and la. 4.5 Withdrawal force The leader tape. and trailer tape which are spliced to each end of the magnetic tape shall be so attached to the reels that they can with
15、stand a withdrawal force of 20 N. 4.6 Guiding groove The cassette shall be provided with a guiding groove for correct insertion into the record/playback equipment as shown in figures 1 and la. 4.7 Safety cap and safety hole The safety hole to prevent accidental erasure is shown in figures 2 and 2a.
16、Recording shall be possible only when the hole is covered by the safety cap as shown in the figures. 4.8 Automatic stop The optical transmittance of the leader and the trailer tape shall be at least 30 % to ensure that the automatic stopping device of the machine functions properly at both ends of t
17、he magnetic tape. 4.9 Cassette support areas The cassette shall be supported by the record/playback equipment only on the four datum points at the locations shown in figures 5 and 5a. (The supports are on the record/ playback machine.) CENELEC EN*b07L2 94 m 3404583 0171444 784 m Page 8 EN 60712 : 19
18、94 Flange diameter mm Hub diameter (SlJPPiY 4) mm I 4. I O Reels Type I Type II Type I Type II (playing time (playing he (Playing lime (piayina th 60 min) 30 min) 20 min) 10 min) 121 121 87 87 38 80 38 80 4.1 O. 1 Arrangement of reels The supply reel shall be placed in the shell with its larger flan
19、ge side down and the tape-up reel is laced with its larger flange side up. 4.1 0.2 Dimensions of reels The dimensions of the reels shall be shown in figures 3 and 3a. Choice of hub diameter is as shown below. SECTION 3: VIDEOCASSETTE RECORDERS 5 Mechanical parameters 5.1 Type of videocassette record
20、er The videocassette recorder shall be of the helical-scan type with two video heads. 5.2 Dimensions and other characteristics are given in figures 4 and 4a and table 1. Reel spindle of videocassette recorder 5.3 Back tension Back tension at the maximum amount of tape on the supply reel shall be bet
21、ween 0.60 N and 0,80 N at the entrance of the drum as indicated in figure 6. The range of tension between the maximum and minimum amount of winding shall be set as follows: tension at minimum amount of winding (38 0) tension at maximum amount of winding (1 18 0) = 1.3 5.4 The distance on the tape pa
22、ttern from the end of the 180“ scan of video head (So) to the audio and control head position is 74.0 f 0,5 mm, dimension (X) as shown in figure 8. Audio and control head position 5.5 Audio and control head dimensions and tolerances shall be in accordance with figure 7. Audio and control head dimens
23、ions CENELEC ENwb0712 94 3404583 0171445 bL0 W Page 9 EN 60712 : 1994 5.6 Audio and control-track head position The distance (X) on the tape pattern between the end of the 180“ scan of the video head (So) and the audio and control head position, is 74,O f 0,2 mm. 5.7 Time-code head position For prac
24、tical reasons, it was not possible in the past to specify a single figure for the distance (Y) on the tape from the beginning (Sl) of the 180“ scan of video head to the address head position. The distance was: for studio machines: 93,O f 2,5 mm for portable machines: 45,5 f 2.0 mm. This difference i
25、n distance represents a time difference of 0.5 s which may have to be taken into account or corrected when tapes are interchanged between portable and studio- machines. However, the figure of 453 f 2,0 mm is now to be preferred. 5.8 Tolerances on audio and control heads and time-code head (U-matic H
26、-format) The audio, control and time-code head tolerances shall be in accordance with the follow- ing illustration: Time code head I ln 7 0 z- Audio and control heads I - - - IEC sssm -I (1 80“ scan of video head) NOTE - Audio and control gaps shall be in line. 5.9 Gap azimuth 5.9.1 Recording of lon
27、gitudinal tracks The azimuth of all head gaps used for the recording of longitudinal tracks shall be perpen- dicular to the direction of tape motion. Page 10 EN 60712 : 1994 CENELEC ENsb0712 94 3404583 O17144b 553 5.9.2 Recording of video tracks The azimuth of the video head gaps shall be perpendicu
28、lar to the direction of head motion. 5.1 O Time-code head position tor SP-format The distance on the tape from the beginning of the 180“ scan of video head to the address head position shall be 48 mm i 0,l mm. 6 Tapespeed The tape speed shall be 95,3 f 0.2 mm/s. 7 Track configuration and dimensions
29、The track configuration and dimensions shall be in accordance with figure 8, and table 2. The switching position between the two video heads shall lie between five and eight horizontal scanning lines ahead of the front edge of the vertical synchronizing pulse. The minimum overlap of the two video he
30、ads shall be three horizontal lines on either side of the nominal position, as shown in figure 9. This recording format permits an optional address track, intended for special uses such as editing and cueing. Track dimensions are identified as N and T in table 2. Longitudinal dimensions and electric
31、al recording characteristics under study. The recording head for this track will be located between the main erase head and the video scanner. 7.1 Video track width (U-matic H-format) Video track width (Al) shall be 0,125 f 0,007 mm. 7.2 Video guard-band width (S) shall be 0,040 mm. Video guard-band
32、 width (U-matic H-format) 7.3 Tape edge to upper limit address track (N) shall be 3,4 i 0,l mm. Location of address track (U-matic H-format) -_ 7.4 Switching position between two video heads (U-matic H-format) The switching position between the two video heads shall lie between 0.5 and 3 horizontal
33、scanning lines ahead of the front edge of the field synchronizing pulse. CENELEC EN*b0712 94 3404583 0171447 493 I RF signal Page 11 EN 60712 : 1994 f I i L I 3 lines ! 3 lines Minimum overlap - - I- - - - The minimum overlap of the two video heads shall be 3 horizontal lines on either side of centr
34、e, as shown below: Switching position Front edge of field sync pulse uced field signal I I P 0,5-3 lines IEC S%93 8 Recording characteristics The recording characteristics of videocassette recorders shall be in accordance with the requirements specified in Section 5. SECTION 4: TAPE CHARACTERISTICS
35、9 Type of magnetic tape A high-resolution magnetic tape (e.g. CrO,) should be used. See 11.2. i0 Constructlon and dimensions of the tape 10.1 Magnetic tape thickness The maximum allowable thickness of the magnetic tape, including the coating shall be 27,O pm. NOTE - Tape having total thickness betwe
36、en 27,O pm to 28.5 pm may also be used for cassettes with a playing time substantially less than 60 min. 10.2 Magnetic tape width The width of the magnetic tape shall be 19.00 f 0,03 mm. 10.3 The maximum allowable thickness of the leader tape and trailer tape shall be 45 pm. leader tape and trailer
37、tape thickness 10.4 The length of the leader tape and trailer tape shall be 0,95 f 0,lO m. Leader tape and trailer rape length CENELEC EN*b0712 94 m 3404583 0171448 32T m Page 12 EN 60712 : 1994 Il II II II Magnetic Trailer tape tape tape -b A c-4 1 O. 5 Splicing The leader tape and trailer tape sha
38、ll be spliced as illustrated below. i Cross-sectio.i ot I spliced portion I Coated surface I I I I I I I I I I I I I NOTE - The leader tape must be free of electrostatic charge. If tape is treated for this purpose, then treated side should face same side as magnetically coated surface. The splice ga
39、p between the leader tape and the magnetic tape shall be below 10.6 0,2 mm. 11 Magnetic tape propertles 1 1 . 1 The magnetic coating shall be longitudinally oriented. Magnetic orientation 11.2 Coercivity The coercivity shall be approximately 40 x lo3 A/m to 48 x lo3 A/m (approximately 500 Oe to 600
40、Oe). 11.3 Coercivity (SP tape) The coercivity shall be approximately 56 x lo3 A/m - 64 x lo3 Aim (700 to 800 oersteds). CENELEC EN*bi12 94 3404583 0171449 2bb a Page 13 EN 60712 : 1994 SECTION 5: RECORDING CHARACTERISTICS 12 Luminance channel A = low-pass filter NOTE - The characteristics of the low
41、-pass filter are important in determining the performance of the luminance channel. At this time, specifications for this filter cannot be standardized since different designs are used by various manufacturers. B = pre-emphasis (see 12.4) C = FM modulator D = FM high-pass filter (see 12.2.2) E = rec
42、ording amplifier F = video head 1 = input signal: composite video signal (monochrome) or composite colour signal 2 = FM luminance signal 3 = recording current Luminance channel (SP-format) A C IEC 61493 A Low-pass filter B Non-linear pre-emphasis C Pre-emphasis D FM modulator E FM high-pass filter F
43、 Recording amplifier G Video head 12.1 Modulation system 1 Input signal: composite video signal or composite coiour signai 2 Band-limited FM luminance signal 3 Luminance recording current 9 Chrominance recording current The video information shall be recorded in the form of an RF signal frequency mo
44、dulated by the video signal. The instantaneous frequencies of the RF signal shall vary linearly with respect to the amplitude of the modulating signal. 12.2 Recording current 12.2.1 bandwidth. The recording current shall have the optimum value over the entire FM carrier For U-matic H-format the reco
45、rding current shall be the optimum record current at 5,3 MHz over the entire FM carrier bandwidth. CENELEC ENlrb0712 q4 3404583 0171450 TBB a Page 14 EN 60712:1994 For SP format the recording current shall be the optimum record current at frequencies shown in the table below over the entire FM carri
46、er bandwidth. I 62550 I 52360 I 6.1 MHz 5.5 MHt NOTE - Optimum record current is the recording current value n., is necessary to c-tain the maximum output signal level during playback. 12.2.2 The amplitude/frequency response of the FM high-pass filter shall be in accordance with the figure below. Re
47、sponse 1 I I 20 dB (6 dB) IV I r I I Applies to H-format 12.2.3 Low-pass filtering (U-matic H-format) For the colour mode, the specifications of low-pass filter A are: - attenuation at fc: 26 dB - attenuation between fc f 0,5 MHz: I5 dB NOTE - In PAL, $ = chrominance sub-carrier frequency; in SECAM,
48、 f, = y2 (foR + foe). 12.3 Characteristic frequencies The instantaneous frequency corresponding to characteristic levels of the video signal is given below. CENELEC ENrb0712 94 Reference video level Sync tip Peak white 3404583 0171451 914 625150 525160 instantaneous Instantaneous frequency Tolerance
49、 frequency Tolerance 5.6 MHz (nom.) - 5 MHz (nom.) - 6,6 MHz f0,l MHz 7,2 MHz f0,l MHz Page 15 EN 60712 : 1994 Convened carner chrominance signal Monochrome - FM signai bandwidth - - r Colour - FM signal bandwidth i Frequency deviation f, r f2 I I I l I I O 1 2 3 4 5 6 7 _t MHz Sync tip frequency i- - Peak white frequency - JW/iyI f, = sync tip frequency f2 = peak white frequency: 3,8 f 0,l MHz 5,4 f 0,l MHz 1,6 i 0,l MHz frequency deviation: 12.3.1 Characteristic frequencies for U-matic H-format are given below. f,= sync tip frequency: 4,8 (nom.) MHz f2 = peak wh
