Pioneer tuning fork Service Manual page 17

T o find out the polarity of the modulation axis of
(ER-EY), burst signal phase is shifted by 90° every line.
If the chrominance subcarrier frequency (Fc) is made a half
of the horizontal scanning frequency multiplied by an odd
number as in NTSC system, the (R - Y) component will
be in phase between the adjacent scanning lines, and ver­
tical stripes will appear. The chrominance carrier frequen­
cy, therefore, is determined by the following equation:
1st field
Pedestal level
Black level
White level
2nd field
S E C A M SYSTEM
In the S E C A M system the sub-carrier is
modulated by (R - Y) on one line and (B - Y) on the next
instead of being modulated by the two color difference
Equalizing Vertical sync
pulses pulses
Vertical retrace blanking period
End of the last (bottom)
horizontal scanning
line in the 2nd field
Video carrier null level
End of the 1st field
Video carrier null level
NTSC
A. SIGNAL IN THE
Field sync
datum line
Burst blanking : 1st Field
Burst blanking : 2nd Field
Burst blanking : 3rd Field
Burst blanking : 4TH Field
Burst phase Burst phase
135° ('NTSC-lines') 225° ('PAL-lines')
b. 625-line PAL video signal
Fig. 6 Video signal waveforms during the field blanking period
frequency
fc = (284-1/4) X f
H
Provided: f = 15,625
H
Thus the color carrier energy is interleaved in luminance
signal spectrum fo/4 out of phase from it. T o make the
dots invisible in 625-line system, 25Hz (fu/625) is added.
Fig. 6 shows the waveforms of N T S C and P A L video sig­
/
nals during the field blanking period.
Horizontal sync
_Equalizing _
pulses
pulses
Beginning of the 1st (top),
line of the 1st field
Beginning of the
2nd field
1st
AND 2 N D FIELDS
4th Field
1st Field
2nd Field
3rd Field
signals simultaneously. Details are omitted here because
we are not manufacturing video equipment of this type at
the moment.
+ (f /625) = 4.4336 MHz
H
Hz
Picture information
a-
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