VDP3104B Ver la hoja de datos (PDF) - Micronas

Número de pieza

componentes Descripción

Fabricante

VDP3104B

Video Processor Family

Micronas 

VDP 31xxB

PRELIMINARY DATA SHEET

2.3. Color Decoder

In this block, the standard luma/chroma separation and

multi-standard 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 Fig.

2–5. The luma as well as the chroma processing, is

shown here. The color decoder provides also some spe-

cial modes, e.g. wide band chroma format which is in-

tended for S-VHS wide bandwidth chroma.

If the adaptive comb filter is used for luma chroma sepa-

ration, the color decoder uses the S-VHS mode proces-

sing. The output of the color decoder is YCrCb in a 4:2:2

format.

2.3.1. IF-Compensation

With off-air or mistuned reception, any attenuation at

higher frequencies or asymmetry around the color sub-

carrier 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 frequen-

cies. It is provided for SECAM signals that are decoded

using a SAW filter specified originally for the PAL stan-

dard.

Fig. 2–4: Frequency response of chroma

IF-compensation

Luma / CVBS

1 H Delay

Notch

Filter

Cross-Switch

Luma

Chroma / CrCb

Chroma

Fig. 2–5: Color decoder

10

IF Compensation

DC-Reject

MIXER

Lowpass Filter

Phase/Freq

Demodulator

ACC

Color-PLL / Color-ACC

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