TDA8501 Datasheet, PDF (8/30 Pages) NXP Semiconductors – PAL/NTSC encoder

Philips Semiconductors
PAL/NTSC encoder
Preliminary specification
TDA8501
CHROMINANCE BLANKING
The signal outputs from the modulators are connected to
the signal input of the chrominance blanking circuit. To
avoid signal distortion that may be caused by the control
loop, the signal outputs of the modulators are blanked
during the sync period. This prevents signal distortion
during the adding of the sync pulse at the CVBS output
circuit.
BANDPASS FILTER
A wide symmetrical bandpass filter is used so that a
maximum performance of the chrominance for Y +C
(SVHS) is guaranteed. This wide curve is possible
because of the minimal signal level of the harmonics within
the modulators see Figs (PAL mode: 5 and 6);
(NTSC mode: 7 and 8) which illustrate the nominal
response for PAL and NTSC modes.
Fig.5 Band pass filter nominal frequency
response (PAL mode).
(1) frequency response.
(2) group delay.
Fig.6 Band pass filter nominal frequency/group
delay response (PAL mode).
April 1993
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