CXD2510Q
§3-2. Frame Sync Protection
• In a CD player operating at normal speed, a frame sync is recorded approximately every 136µs (7.35kHz).
This signal is used as a reference to know which data is 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 CXD2510Q, window protection and forward protection/backward protection have been adopted for
frame sync protection. The adoption of these functions achieves 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 fixed to 13, and the backward protection counter to 3. In other words, 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 frame sync cannot be detected for 13 frames or more, the window is released and the frame sync is
resynchronized.
In addition, immediately after the window is released and the resynchronization is executed, if a proper
frame sync cannot be detected within 3 frames, the window is released immediately.
§3-3. 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 CXD2510Q 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 outside the LSI.
See the Table 3-2.
• 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 MNT2 MNT1 MNT0
Description
; C1 pointer reset
; C1 pointer reset
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
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
; C1 pointer set
One C1 error corrected
Two C1 errors corrected
C1 correction impossible
No C2 errors
; C1 pointer set
; C1 pointer set
; C1 pointer set
; C2 pointer reset
; C2 pointer reset
; C2 pointer reset
; C2 pointer reset
; C2 pointer reset
One C2 error corrected
Two C2 errors corrected
Three C2 errors corrected
Four C2 errors corrected
—
C2 correction impossible
C2 correction impossible
; C1 pointer copy
; C2 pointer set
Table 3-2.
– 33 –
SONY [ SONY CORPORATION ]
