VPC3211C View Datasheet(PDF) - Micronas

Part Name

Description

View to exact match

VPC3211C

VPC3205C, VPC3215C Video Processor Family

Micronas 

PRELIMINARY DATA SHEET

VPC 3205C, VPC 3215C

The ACC has a control range of +30 ... –6 dB.

For SECAM decoding, the frequency of the burst is

measured. Thus, the current chroma carrier frequency

can be identified and is used to control the SECAM

processing. The burst measurements also control the

color killer operation; they can be used for automatic

standard detection as well.

PAL/NTSC

SECAM

Fig. 2–5: Frequency response of chroma filters

2.3.4. Frequency Demodulator

The frequency demodulator for demodulating the SE-

CAM signal is implemented as a CORDIC-structure. It

calculates the phase and magnitude of the quadrature

components by coordinate rotation.

The phase output of the CORDIC processor is differ-

entiated to obtain the demodulated frequency. After

the deemphasis filter, the Dr and Db signals are scaled

to standard CrCb amplitudes and fed to the cross-

over-switch.

2.3.5. Burst Detection

In the PAL/NTSC-system the burst is the reference for

the color signal. The phase and magnitude outputs of

the CORDIC are gated with the color key and used for

controlling the phase-lock-loop (APC) of the demodula-

tor and the automatic color control (ACC) in PAL/NTSC.

2.3.6. Color Killer Operation

The color killer uses the burst-phase/burst-frequency

measurement to identify a PAL/NTSC or SECAM color

signal. For PAL/NTSC, the color is switched off (killed)

as long as the color subcarrier PLL is not locked. For

SECAM, the killer is controlled by the toggle of the

burst frequency. The burst amplitude measurement is

used to switch-off the color if the burst amplitude is

below a programmable threshold. Thus, color will be

killed for very noisy signals. The color amplitude killer

has a programmable hysteresis.

2.3.7. PAL Compensation/1-H Comb Filter

The color decoder uses one fully integrated delay line.

Only active video is stored.

The delay line application depends on the color stan-

dard:

– NTSC: 1-H comb filter or color compensation

– PAL: color compensation

– SECAM: crossover-switch

In the NTSC compensated mode, Fig. 2–6 c), the color

signal is averaged for two adjacent lines. Thus,

cross-color distortion and chroma noise is reduced. In

the NTSC 1-H comb filter mode, Fig. 2–6 d), the delay

line is in the composite signal path, thus allowing

reduction of cross-color components, as well as

cross-luminance. The loss of vertical resolution in the

luminance channel is compensated by adding the ver-

tical detail signal with removed color information. If the

4H adaptive comb filter is used, the 1-H NTSC comb

filter has to be deselected.

Micronas

9

Share Link: