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Panasonic Z-421V Technical Manual
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Contents
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3DQDVRQLF402.2 RECORD AND PLAYBACK PROCESSING CIRCUIT2.2.1 RECORD PROCESSING35 Video AGC Sync. Sep.FBC37VideoInputMICOM 93rd pinPre-amp IC 5th pinLuminance Signal ProcessingChrominance Signal ProcessingRecord ProcessingThe video input signal selected by the AV switching IC among AUX video input and IF video input, issupplied 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 andsupplied 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 ofMICOM 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 signalprocessing part independently.1) LUMINANCE SIGNAL PROCESSING (RECORD)N.L.FBC 25LPF1/2 YNR Buffer 26 Clamp DetailEnhancerMainFM MODRec EQRec EQ425401871H DelayEmphasis EmphasisLuminance Signal Processing (RECORD)(LC89978M)Pre-amp 9th pinThe input signal through FBC is reduced a half (6dB) of its level and then the pure luminance signal isobtained by LOW-PASS FILTER. In YNR (Luminance Noise Reduction) circuit, noise is eliminated using theoriginal 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 isSECAM 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 frequencymodulation.The luminance signal is FM-modulated and then is supplied to RECORD EQUALIZER for compensating thehigh frequency response related to HEAD characteristic, where its RECORD EQ is determined by theGroup 4, LSB 1-4bits of I 2 C serial control. |
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