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7-4-2. Speed and Phase Detection and Servo Signal
Generation
Detection of the phase and speed and processing of the
servo signal are carried out by CXP80724 in the same
manner as the drum servo system.
Fig. 7-5. shows a diagrammatical representation of the
processing inside the IC.
The C FG input to Pin @ is divided by n, and then phase
and speed detection of the (CFG/n} signal are carried out.
(The d ivision ratio is n
=
The phase detection in both the recording mode and the
playback mode are processed in exactly the same way as in
the drum system.
After both data have been added, the signal is DA
converted and output from Pin @ as the PWM wave (CAP.
PWM) .
CFG
ATF
ERROR
1 for normal playback.)
1 /N
(
N
REC PLAY N=1
CUE
REV
ND
Fig. 7-5. Capstan Servo Processing Circuit
7-4-3. Capstan Motor Driver
The LB1 857M (IC361 ) is used as the capstan drive IC.
7-4-4. Control Signal and Signal Adjustment
[Capstan driver control signal]
This is output from CXP80724 and input to LB1 857M.
CAP F/R : Pin @
Input LP : Forward direction
IC351 CXP80724
SPEED
D ETECT
)
N=9
N=7
PHASE
DETECT
- 4-46 -
SERVO
PROCESS
CAP. PWM
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