Table of Contents
Advertisement
3DQDVRQLF
2.2 RECORD AND PLAYBACK PROCESSING CIRCUIT
2.2.1 RECORD PROCESSING
Video
35
Input
The video input signal selected by the AV switching IC among AUX video input and IF video input, is
supplied to the 35th pin of AV 1CHIP IC.
The input video signal is then automatically adjusted to suitable level by the built-in AGC circuit and
supplied to SYNC separation and FBC(feedback clamp) part respectively .
SYNC signal obtained from the composite video signal by SYB SEP circuit is supplied to the 93rd pin of
MICOM to determine the presence of signal and to control the SERVO LOGIC,
In SECAM-L IV, SYNC signal is used for BPG and SYNC noise gate pulse, and in PRE-AMP,
for HEAD-AMP switching timing on TRICK PLAY and AGC circuit for self-adjustment of the record bias.
The signal through FBC is processed in luminance signal processing part and chrominance signal
processing part independently.
1) LUMINANCE SIGNAL PROCESSING (RECORD)
1/2
FBC
1H Delay
7
(LC89978M)
18
Pre-amp 9th pin
The input signal through FBC is reduced a half (6dB) of its level and then the pure luminance signal is
obtained by LOW-PASS FILTER. In YNR (Luminance Noise Reduction) circuit, noise is eliminated using the
original signal and 1H delayed signal.
This signal is then supplied to 400nS-delay filter, but this filter is so activated only if the input video signal is
SECAM as to compensate the Y-C mismatching due to the SECAM signal processing nature.
The detail enhancer enhances overall high-frequency response, so an object with fine lines (such as a lawn,
hair etc.) can be seen more clearly during playback.
The nonlinear Emphasis and Main Emphasis can minimize the triangular noise susceptible to frequency
modulation.
The luminance signal is FM-modulated and then is supplied to RECORD EQUALIZER for compensating the
high frequency response related to HEAD characteristic, where its RECORD EQ is determined by the
Group 4, LSB 1-4bits of I
Video AGC
Record Processing
YNR
LPF
5
42
40
Rec EQ
Rec EQ
Luminance Signal Processing (RECORD)
2
C serial control.
Sync. Sep.
37
FBC
25
26
Buffer
FM MOD
40
MICOM 93rd pin
Pre-amp IC 5th pin
Luminance Signal Processing
Chrominance Signal Processing
Detail
Clamp
Enhancer
Main
N.L.
Emphasis
Emphasis
Advertisement
Table of Contents
