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DFG
IN
OUT
DPG
IN
OUT
3 0 DEG
T l
N TSC
2.8
PAL
3.3
7-3-2. RF SW Signal Generation
The RF SW signal, which is a signal for switching between
the two heads, is generated based on the DFG and DPG.
[ Switching point adjustment]
The signal recording position on the tape is determined by
the switching timing of the RF SW signal. The RF SW signal
is generated by d ividing the DFG by 1 2. Its polarity
alternates according to the pattern Hi-Low-Hi for each 1 80
degrees of rotation.
There is a variable delay circuit for correcting the deviation
of the switchi ng timing due to variations in the DFG
mounting positions.
The amount of delay can be adjusted by means of the AD
input to Pin @ of CXP80724.
(A) RF SW
(B) REC CHA
(C) REC CHB
(D) SEL 1
(REC)
(E) SEL 2
(REC)
(F) JOG VD
(CU E OR REV)
360 DEG
T2
fl ( Hz ) f2 ( Hz )
33.4
3 6 0
30
300
40.0
25
Fig. 7-1 .
The RF SW signal is output from Pin @ of CXP80724. The
switching point is adjusted by playing back a properly
recorded alignment tape to adjust the RF SW timing, and
adjusting by means of VR351 .
[Video signal recording phase (7H) setting]
During recording, the vertical sync pulse is recorded onto
the tape in a specified position (7H after the RF SW sign al
switching point).
[Video control signal]
Various signals are generated by CXP80724 based on the
RF SW signal and are output, and these signals are used to
control the video circuits. Fig. 7-2. shows the waveforms of
these various signals.
Fig. 7-2.
- 4-43 -
IC3 8 1
L B 1 8 8 5
}
@)
PU LSE/REV. (360 ° )
1 2
DEG : Degree
CXP80724
(1 00) OUT
JOG VD: Q uasi vertical sync signal
(90) OUT
(1 ) OUT
(90) OUT
(96) OUT
(93) OUT
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