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7-7.
CUE/REVIEW PLAYBACK
In general, when playback a tape with "n" times speed,
noise
bars
correspond
to (n—1) tracks
appear
on the
screen due to across (n—1) reverse azimuth tracks per one
frame.
When "n' is selected to an odd number, a half the number
of "n" bars will appear on the screen
due to two bars
overlapping at the field intervals.
When
selecting the cue/review speeds to 9/~7 times the
normal
speed,
only four noise bars will appear
on the
screen,
7-7-1.
Tracking Phase Detection
The phase in cue/review mod is detected by ATF error
signal as well as normal playback.
When
the. standard
pilot signal Ref is changed
several
times in 1 field, the phase of tracking can be detected.
The servo being locked,the noise-bar is seen like standstill.
RF Swe
RE SWO
REF PILOT
REV Ix-7
16K GR
ALL LOW?
(Lv60S0W
ANA
ACN IA A
reat NNN
NN
IY AN AA
AN
mee" TUN UN UN UN UN UN UN UR VN YR
RF swt
RF Sw
REF PItoT
MEAD TRACE
4exur
{laside
Lvsosow) texHr
ae
es
CUE
IKO1
<
<q _
wom t AV JA VA JA
RF
ATF ERROR
IN i
2
\
I
a
3
wags TUN
VA YN
N
Fig. 7-18.
Cue/review playback
7-14
7-7-2.
Fh Correction
In cue/review playback, the relative speed between tape
and
heads
changes
and
the time
base
of the playback
video
signal expands/shrinks
due
to the head
tracing
across the several tracks, causing changes in the colors,
etc. In order to prevent this, the rotational speed of the
drum
is slightly altered to correct to the same
relative
speed as normal playback.
An fh correction refers to making the playback horizontal
sync frequencies the same.
The
rotational
speed
correction
factor is given by the
following equation:
1=625/(625-2 aH * (n—1))
aH=2 (SP)
=1 (LP)
When
n=9/-7
in
the
cue/review,
correction
of
approximately + 5.3% is performed.
The
tape
speed
(capstan
rotational
approximately 9/7 times after correction.
The CFG frequency is shown in Table 7-4.
speed)
is
PAL (SP)
PAL (LP)
Table 7-4.
7-7-3,
Pseudo Vertical Sync Signal
When the rotational speed is altered by fh correction, the
frequency of the playback vertical syne signal changes. If
noise appears in the vicinity of the vertical sync, vertical
syne separation is lost and the vertical vibration could be
cause on the screen.
In order to prevent this, a pseudo
vertical syne signal (JOG VD) is inserted into the video
signal
with
the
timing
of the
RFSW
signal,
during
cue/review playback. JOG VD signal is output from Pin @
of CXP80720 (IC351)
Fig. 7-8 shows the timing chart.
oa
Speed
on
ini
Correction | Speed
Hs
eh
Correction}
CFG
| CFG/N
correction!
x1
993
993
0%
xt
1389
1389
0%
694
694
0%
xg
9225
1025
3%
x9
13176.|
1464
5%
6588
732
+3%
aaa |e
Xx -7
6748
964
-3%
x-7
9247
1321
~5%
4627
661
-3%
X13
13533
1041
5%
x9
13176
1464
5%
6588
732
3%
——+-
_—
—.
4%
X-7
| 9247
1321
5%
-3%
CFG
7-15
Frequency
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