IEC 60843-4 pdf download – Helical-scan video tape cassette system using 8 mm magnetic tape (8 mm video) – Part 4: Video subcode (VSC)

IEC 60843-4 pdf download – Helical-scan video tape cassette system using 8 mm magnetic tape (8 mm video) – Part 4: Video subcode (VSC)
1General
1.1Scope
This part of lEC 60843 specifies a method of auxiliary data recording and playback withthe IEC 60843 8 mm video system.This part is applicable to both 525 line – 60 field and625 line – 50 field television systems.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text,constitute provisions of this part of lEC 60843.For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply.However, parties toagreements based on this part of lEC 60843 are encouraged to investigate the possibility ofapplying the most recent editions of the normative documents indicated below.For undatedreferences, the latest edition of the normative document referred to applies. Members of lECand Iso maintain registers of currently valid International Standards.
IEC 60461:1986,Time and control code for video tape recorders
IEC 60843 (all parts), Helical-scan video tape cassette system using 8 mm magnetic tape
2 Area allocation and dimensions
2.1Types of video subcode (vsc)
There are two types of vsC which are 1 block VSC and 5 block vsc.
2.21 block vsc
Figure 1 shows the recording area of 1 block vsc.
The recording area of 1 block vSC shall be specified by the head switching point.
All of the data area, search mark and erase code should be recorded.
2.35 block vsc
2.3.1 5 block vsc with PCM audio
Figure 2 shows the recording area of 5 block VSC with PCM audio.
The recording area of 5 block VSC with PCM audio shall be specified by the distance from thehead switching point.
All the data area, search mark and erase code should be recorded.
The erase code should have a variable length relative to the position of PCM data area.
2.3.25 block vsC without PCM audio
Figure 3 shows the recording area of 5 block vSC without PCM audio.
The recording area of 5 block vSC without PCM audio shall be specified by the distance fromthe head switching point.
All of the data area, search mark and erase code should be recorded.
3Data structure
3.11 block vsc
Figure 4 shows the data area of 1 block vSc.
1 block vSc consists of a block named Block 4.
Block 4 is common to 5 block vSC and 1 block vSc.
3.25 block vsc
Figure 5 shows the data area of 5 block vSc.
5 block VSC has an extended data area from Block 0 to Block 3.
4Channel coding
4.1 Modulation
The modulation method shall be a bi-phase mark, except for the synchronization code.
4.2Transmission rate
The transmission rate shall be 368 times the horizontal sync frequency, 5,79 Mbit’s for the525 line – 60 field system and 5,75 Mbit/s for the 625 line- 50 field system.
4.3Erase code
The erase code shall be all “1~.
4.4Search mark
The data sign of the search mark shall be all “0T for enable.
The data sign of the search mark shall be all “1” for disable.
Table 1 shows the recording condition of the search mark.
4.5Synchronization code
Figure 6 shows the synchronization code.
The synchronization code indicates the start position of each CRC block.
4.6End mark
The end mark shows the end of the data area.
The end mark consists of 12 successive synchronization codes.
5 Data contents
5.1 Block
Table 2 shows the contents of the block.
A block consists of the synchronization code, five words and the CRC code.
Blocks from Block 0 to Block 3 shall be used with 5 block vSC only.
Block 4 is common to 5 block vSC and 1 block vSc.
5.2word
Table 3 shows the contents of the word.
Word 0 shows the mode which indicates a category of data code.
Words from Word 1 to Word 4 consist of the data code for the mode.
5.3cRC code and error detection
The error detection system shall be based on the CRC method.
The CRC block consists of five words and the CRC code.
The CRC code contains 8 bits and its generator polynomial G(x) shall be as follows: