ADVANCE INFORMATION
VDP 313xY
2.4.1. IF-Compensation
With off-air or mistuned reception, any attenuation at
higher frequencies or asymmetry around the color
subcarrier is compensated. Four different settings of
the IF-compensation are possible:
– flat (no compensation)
– 6 dB/octave
– 12 dB/octave
– 10 dB/MHz
The last setting gives a very large boost to high fre-
quencies. It is provided for SECAM signals that are
decoded using a SAW filter specified originally for the
PAL standard.
2.4. Color Decoder
In this block, the standard luminance/chrominance
(luma/chroma) separation and multistandard color
demodulation is carried out. The color demodulation
uses an asynchronous clock, thus allowing a unified
architecture for all color standards.
A block diagram of the color decoder is shown in
processing, is shown here. The color decoder provides
also some special modes, e.g. wide band chrominance
format which is intended for S-VHS wide bandwidth
chrominance.
If the adaptive comb filter is used for luminance/
chrominance separation, the color decoder uses the
S-VHS mode processing. The output of the color
decoder is YC
R
C
B
in a 4:2:2 format.
Fig. 2–2:
Frequency response of chrominance IF-com-
pensation
Luma / CVBS
Notch
Filter
Luma
MUX
1 H Delay
CrossSwitch
Chroma
ACC
MUX
IF Compensation
DC-Reject
Mixer
Lowpass Filter
Phase/Freq
Demodulator
Chroma
ColorPLL/ColorACC
Fig. 2–3:
Color decoder
Micronas
9
MICRONAS [ MICRONAS ]
