Panasonic EURO 4 Chassis Technical Manual page 44

3DQDVRQLF
17.4. Adaptive Comb Filter
Introduction
The digital CVBS signal fed from the previous
front-end stage is fed to the adaptive comb filter
stage which is used to produce high-quality
luminance/chrominance separation for PAL or NTSC
signals. The comb filter improves the luminance
resolution by allowing the full 5MHz bandwidth to be
achieved even during colour transmissions. Without
the use of a comb filter, the luminance resolution is
limited about 3.8 MHz.
Adaptive Combfilter
CVBS
Input
Chroma
Input
1H Line Delay
1H Line Delay
The comb filter also reduces interferences like
cross-luminance and cross-colour artifacts without
introducing new artifacts or noise.
Where an S-VHS signal or SECAM signal is input
then the comb filter is switched off, in this case the
signals are fed via the delay lines directly to the
Colour decoder stage. This also applies where the
comb filter is switched off via software control.
Bandpass
Filter
Bandpass /
Notch
Filter
Bandpass
Filter
44
Luma
Output
Luma / Chroma
Mixers
Adaption Logic
Chroma
Output