CXD3008Q Datasheet, PDF (69/131 Pages) Sony Corporation – CD Digital Signal Processor with Built-in Digital Servo

CXD3008Q
§ 4-2. Frame sync protection
• In normal speed playback, a frame sync is recorded approximately every 136µs (7.35kHz). This signal is
used as a reference to recognize the data within a frame. Conversely, if the frame sync cannot be
recognized, the data is processed as error data because the data cannot be recognized. As a result,
recognizing the frame sync properly is extremely important for improving playability.
• In the CXD3008Q, window protection and forward protection/backward protection have been adopted for
frame sync protection. These functions achieve very powerful frame sync protection. There are two window
widths; one for cases where a rotational disturbance affects the player and the other for cases where there is
no rotational disturbance (WSEL = 0/1). In addition, the forward protection counter is set to 13^∗, and the
backward protection counter to 3^∗. Concretely, when the frame sync is being played back normally and then
cannot be detected due to scratches, a maximum of 13 frames are inserted. If the frame sync cannot be
detected for 13 frames or more, the window opens to resynchronize the frame sync.
In addition, immediately after the window opens and the resynchronization is executed, if a proper frame
sync cannot be detected within 3 frames, the window opens immediately.
∗ _{Default values. These values can be set as desired by $C commands SFP0 to SFP3 and SRP0 to SRP3.}
§ 4-3. Error Correction
• In the CD format, one 8-bit data contains two error correction codes, C1 and C2. For C1 correction, the code
is created with 28-byte information and 4-byte C1 parity.
For C2 correction, the code is created with 24-byte information and 4-byte parity.
Both C1 and C2 are Reed Solomon codes with a minimum distance of 5.
• The CXD3008Q uses refined super strategy to achieve double correction for C1 and quadruple correction for C2.
• In addition, to prevent C2 miscorrection, a C1 pointer is attached to data after C1 correction according to the
C1 error status, the playback status of the EFM signal, and the operating status of the player.
• The correction status can be monitored externally.
See Table 4-2.
• When the C2 pointer is high, the data in question was uncorrectable. Either the pre-value was held or an
average value interpolation was made for the data.
MNT3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
MNT2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
MNT1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
MNT0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
No C1 errors;
One C1 error corrected;
No C1 errors;
One C1 error corrected;
Two C1 errors corrected;
C1 correction impossible;
No C2 errors;
One C2 error corrected;
Two C2 errors corrected;
Three C2 errors corrected;
Four C2 errors corrected;
C2 correction impossible;
C2 correction impossible;
Table 4-2.
– 69 –
Description
C1 pointer reset
C1 pointer reset
—
—
C1 pointer set
C1 pointer set
C1 pointer set
C1 pointer set
C2 pointer reset
C2 pointer reset
C2 pointer reset
C2 pointer reset
C2 pointer reset
—
C1 pointer copy
C2 pointer set