JVC GR-DVA10 Technical Guide

3-2
Sync Area
ID
Code
VIDEO AUX (VAUX)
VIDEO DATA
Inner
Parity
Outer Parity
Sync block
number
012345 9 81 89
18
19
20
Byte-position number
Pre-sync
block (2)
Data-sync
block
(149)
Post-sync
block (1)
Sync Block length : 90 Byte
77 8
17
21
156
157
167
168
VIDEO AUX (VAUX)
Fig. 3-1-2 Structure of sync blocks in video sector
The length of sync blocks of the sub code is just 12 bytes. The sub code has the fast search function to
search the target point at a high speed. In the fast search mode, if the tape speed is increased, the angle
that the head scans the track is decreased and the form of signals that can be read by one scanning
becomes like beads on an abacus. If data of signals read by one scanning are not grouped as a sync
block, those data cannot be decoded and played back. Therefore, the length of a sync block is shortened
to secure the reproducibility of data. Since the probability to pick up the outer parity is very low in the fast
search mode, no outer parity is prepared in the sub code differently from the AUDIO/VIDEO sector. In
order to secure the reproducibility and reliability of playback data, the same data is not only written twice in
different parts of a track but also written in a half of a frame (in 5 or 6 tracks). In other words, the same
data is written over and over 10 times or 12 times in the tracks of the first half of a frame. The next data is
multiply written in the second half of the frame in the same manner, namely, written 10 times or 12 times
repeatedly.
Sync Area
ID
Code
Sub-code
DATA
Inner Parity
Sync block
number
012345
0
1
2
3
7
4
5
6
8
9
10
11
Byte-position number
Data-sync
block
Sync Block length : 12 Byte
67891011
Fig. 3-1-3 Structure of sync blocks in subcode sector

JVC GR-DVA10 Specifications

General

Brand	JVC
Model	GR-DVA10
Category	Camcorder
Language	English