1、- SMPTE 2451 93 8357401 0000786 471 SMPTE STANDARD ANSI/SMPTE 245M-.1993 for Television Digital Recording - 19-mm Type D-2 Composite Format - Tape Record 1 Scope This standard specifies the dimensions and location of the audio, video, ancillary data, cue track, time code, and control-track records f
2、or 19-mm type D-2 helical-scan composite digital cassette television tape recorders operating on the 525/60 television system encoded according to ANSVSMPTE 244M. 2 General specifications 2.1 Dimensions are in the metric system. 2.2 Tests and measurements made on the tape record to check the require
3、ments of this standard shall be made under the following atmospheric conditions unless otherwise stated: - Temperature 20C shifting one track, the second tolerance zone can be measured and so on. It is not necessary to measure all tracks; a suitable number is 20 samples per zone. A plot of the track
4、 location error against the track number shall be computed (see figure A.4). The peak-to-peak value shall lie within the tolerance zones ac- cording to clause 5.3. from the corrected longitudinal track pitch and the theoreti- -I Measurement path I k- Li -fA-4 Reference edge / L Control track servo r
5、eference pulses NOTES 1 i is the track number (i = O for the track containing the program reference point). 2 Yi is the actual track position (measured from the reference edge of the tape). 3 LI is the distance of n control track pitches (n = 200 minimum). Figure A.l - Measurement of ferrofluid tape
6、 development The measured distance, Li, must be corrected for tape tension. The corrected tape length, L2 (for n control track pitches), is: L2 = LI x (1 tT/(A x E) where T is the tape tension (0.7 N) A is the tape cross section area (0.013 mm x 19.01 mm) E is Youngs modulus (IO O00 N/mm2). AL Figur
7、e A.2 - Correction for tape tension Page 6 of 8 pages SMPTE 245M 93 9 8357401 O000992 795 I ANCI/SMPTE 245M-1993 Same head (.e., every fourth track) The corrected longitudinal track pitch, L3, is: where L3 = W(n x q) L2 is the corrected tape length for n control track pitches; 0 q is the number of t
8、racks per control track pitch (2). The cross track pitch, AY, is: where AY = L3 x tan (0) b is the corrected track length; 0 is the theoretical track angle (6.1296). ix L3 The theoretical track position, Yit, to any track i is: where Yfi = Y+( x AY) Y is the distance to the program reference point (
9、2.80 mm); i is the track number (i = O for the track containing the program reference point); AY is the cross tape track pitch. The track location error, TLE, is calculated as: where TLE = yi-Yfi Yi is the actual track position of track i; Ya is the theoretical track position of track i. Figure A.3
10、- Calculation of track location error TLE NOTES 1 For tolerance zone 1 : i = . -4, O, +4, +8 2 For tolerance zone 2: i = . -5, -1, +3, +7 3 For tolerance zone 3: i = . -6, -2, +2, +6 4 For tolerance zone 4: i = . -7, -3, +1, +5 Figure A.4 - Example plot of track location error versus track number Pa
11、ge 7 of 8 pages SUPTE 2451 93 357403 0000993 623 ANSI/SMPTE 245M-1993 Annex B (informative) Bibliography ANSI/SMPTE 244M-1993; Television - System M/NTSC Composite Video Signals - Bit-Parallel Digital Interface ANSI/SMPTE 246M-1993, Television Digital Recording - 19-mm Type D-2 Composite Format - Ma
12、gnetic Tape ANSVSMPTE 247M-1993, Television Digital Recording - 19-mm Type 0-2 Composite Format - Helical Data and Control Records ANSI/SMPTE 248M-1993, Television Digital Recording - 19-mm Type D-2 Composite Format - Cue Record and Time and Control Code Record SMPTE EG 20-1 993, Tape Transport Geometry Parameters for 19-mm Type D-2 Composite Format for Television Digital Recording SMPTE EG 21 -1 993, Nomenclature for Television Digital Recording of 19-mm Type D-1 Component and Type D-2 Composite Formats Page 8 of 8 pages
