VPC3211C View Datasheet(PDF) - Micronas
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VPC3211C Datasheet PDF : 48 Pages
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VPC 3205C, VPC 3215C
PRELIMINARY DATA SHEET
CVBS
8
Notch
filter
Chroma
Process.
a) conventional
Y
CrC b
Luma
8
chroma
8
Chroma
Process.
b) S-VHS
Y
CrC b
CVBS
Notch
Y
8
filter
Chroma
Process.
1H
Delay
c) compensated
CrC b
CVBS
8
1H
Delay
Notch
filter
Y
Chroma
Process.
d) comb filter
Fig. 2–6: NTSC color decoding options
CrC b
CVBS
8
Notch
filter
Luma
8
Chroma
Process.
1H
Delay
a) conventional
Chroma
8
Chroma
Process.
1H
Delay
b) S-VHS
Fig. 2–7: PAL color decoding options
Y
CrC b
Y
CrC b
CVBS
8
Notch
filter
Chroma
Process.
1H
Delay
MUX
Fig. 2–8: SECAM color decoding
Y
Cr C b
10
2.3.8. Luminance Notch Filter
If a composite video signal is applied, the color infor-
mation is suppressed by a programmable notch filter.
The position of the filter center frequency depends on
the subcarrier frequency for PAL/NTSC. For SECAM,
the notch is directly controlled by the chroma carrier
frequency. This considerably reduces the cross-lumi-
nance. The frequency responses for all three systems
are shown in Fig. 2–9.
dB
10
0
–10
–20
–30
–40
MHz
0
2
4
6
8
10
PAL/NTSC notch filter
dB
10
0
–10
–20
–30
–40
0
2
4
6
8
SECAM notch filter
Fig. 2–9: Frequency responses of the luma
notch filter for PAL, NTSC, SECAM
MHz
10
2.3.9. Skew Filtering
The system clock is free-running and not locked to the
TV line frequency. Therefore, the ADC sampling pat-
tern is not orthogonal. The decoded YCrCb signals are
converted to an orthogonal sampling raster by the
skew filters, which are part of the scaler block.
The skew filters are controlled by a skew parameter
and allow the application of a group delay to the input
signals without introducing waveform or frequency
response distortion.
The amount of phase shift of this filter is controlled by
the horizontal PLL1. The accuracy of the filters is 1/32
clocks for luminance and 1/4 clocks for chroma. Thus
the 4:2:2 YCrCb data is in an orthogonal pixel format
even in the case of nonstandard input signals such as
VCR.
Micronas
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