Kenwood DP-3010 Service Manual page 22

DP-3010
40
CIRCUIT DESCRIPTION
® C1 and C2 Revision Circuit
Error Detection and Revision Processing in the CD is done
in twe places, C1 and C2.
1) C1 Detection/Revision Section
For C: Revision Processing. the Error Detection in each
frame of the input data for High Priority Items is done as
foliows: one High Priority Item is deleted and two or more
Items are Error Flag Marked (C1 Ep).
2) C2 Detection/Revision Section
The cata from C1 Detection/Revision Section is De-
interleave Processed and sent to C2 Revision Section.
Here, only when the ratio of a miss judgement is low, Revi-
sion Processing is done.
Because of this, the Ci Ep marks from C1 Revision Section
are used as one judgement information in C2 Revision Sec-
tion. Here upto two High Priority Items are deleted and
three or more errors Correction Flag Marked (C2 Ep) and
are moved the the Correction Output Mode.
The Ci and C2 Judgement Results are output through the
SPDA pin as shown in Diagrams 6-4 and 6-5 and are used
as Monitor Signals.
: No Error
| c1s1 | c1S0 | C1lEp ! Judgement Result
Judgement Result
, No Error
One Error Revised
: Two Errors Revised
Three or more Errors Corrected
Diagram 6-5 C2 Revision Judgement Results
Output Data
Correction Mark
Flag (HOF)
®@ Data Correction Output Circuit
The C2 Revision Processed Data is Scramble Processed
(including two delay processing) under CD standards by
the external RAM Address Control. This data is consecu-
tively read from the externa! RAM in Output Word Order
from the 8 bit LSB side.
The selection of each data between Direct Output, Aver-
age Correction Value Output or Prior Point Hold Output is
done in reference to the C2 Ep Correction Mark Fiags.
An example of the Correction Process Operation is shown
in Diagram 6-10.
Average
Correction
Average
Correction
Diagram 6-10 Correction Process Operation Example
Output Mode
Correction Mark Flag (HOF)
n Dns: |
Direct Output
Average
Correction Value
2
Bn-1
|
| Dn-1+D+1 |
! |
|
Prior Point Hold
Diagram 6-6 Correction Algorithm
Note: When the ~ HOSTP Flag, explained on Page 40, is
set to "L", the Correction Operation is stopped and
changed to Direct Output Mode
This flag is very useful when applied to the CD-ROM
and CD Information Files.
Also, Correction Flag is added to each word data of the
8-bit LSB side (L-HOF) and 8-bit MSB side (M-HOF) indi-
vidually and is output through the HOF pin in the order of
L-HOF and M-HOF to the Correction Data and output
simultaneously.
HOF Correction Alogrythems is set to HOF = 1 if either
L-HOF or M-HOF is 1.
DP-3010
CIRCUIT DESCRIPTION
© Attenuator Circuit
During Search, Fast Forward, and Reverse operations in
the CD Player, there is a need for an Attenuator Circuit to
lower the level of "harmful" sound.
A Fixed Attenuation Level of —12 dB enters from the
SCDA pin where it is decided whether to attenuate or not.
Internal switching is done is accordance to the ~ ATT
Signal.
When ~ ATT = "L", — 12 dB Attenuation
@ Muting Circuit
When an abnormal signal enters. it is detected as an Error
in the Revision Processing Mode and then eliminated in
the Correction Output Circuit. But a certain amount of
Bust Error is repeated and that repeated iow frequecy
sound is output. When a long Bust Error is emitted, the
direct current Signal, a poor quality sound, is output.
To avoid the just mentioned phenomenon, these signals
are passed through the Muting Circuit.
The Muting Operations are explained in the following.
When Muting Operations are started, the Attenuate Cir-
cuit (— 12 dB} comes ON at the same time, and Zero Cross
Detection is done.
The operation for each channel, L and R, are done individu-
ally where when the Zero Cross Data (Marked Beat In-
versed) is detected, Muting is ON and the digital output
data turns to "0".
Muting cancelling is done in the same way.
Control of the Muting Circuit is done with the input com-
mand ~ MUTI and MUTC from the SCDA pin.
~ MUTI: Forced Muting Command
When "L", Muting is forced to ON
MUTI: Internal Muting Control Command
When internal "H" is detected, this command
stands.
MUTING MODE ; SET CONDITIONS RESET CONDITIONS
| When a 64-Frame Burst Error is detected in C1 Revision Mode
DIN-MiSS
When a De-tnterieave Miss occurs three consecutive times.
| When two consecutive revision frames occur in C2
Revision Mode.
BUF-ON i; When the Buffer Capacity exceeds +5 Frames
Diagram 6-7 Internal Muting Commands
Muting OFF
Zero Cross
Detection
o .
Ay
\
\
Loh
DC Offset
Roch
~12 dB
Muting ON
Attenuate ON
Muting OFF
Muting
Condition
Muting
Condition
Diagram 6-11 Muting Operation