论文部分内容阅读
在VHS录像机中,色度信号与亮度信号一样,也是按记录和重放两种状态分别处理的,如图1。一、记录系统记录系统的主要工作是频率变换和消除串信。 1.频率变换图2是一种常见的降频式方框图。带通滤波器从输入视频信号中取出色副载波频率F_s为4.433619MHz彩色成分,并将其送入主变频器(主信号频率变换)。同时,该输入视频信号也送至行同步分离器。分离出来的15.625MHz行频信号F_h经过40倍频后加到移相电路。此40F_h信号中的一场直接加到副变频器(主变频器的本振),另一场经逐行延迟90°后也加到副变频器,这是靠25Hz磁头脉冲来切换的。
In the VHS video recorder, the chrominance signal is the same as the luminance signal, and is also processed separately according to the two states of recording and playback, as shown in FIG. 1. First, the recording system The main work of the recording system is frequency conversion and elimination of string letters. 1. Frequency Conversion Figure 2 is a common down-frequency block diagram. The band-pass filter takes the color sub-carrier frequency F_s of 4.433619 MHz as a color component from the input video signal and sends it to the main inverter (main signal frequency conversion). At the same time, the input video signal is also sent to the line sync separator. Isolated 15.625MHz line frequency signal F_h after 40 times the frequency added to the phase shift circuit. One of the 40F_h signals is directly applied to the sub-frequency converter (the main frequency converter’s local oscillator) and the other is delayed to 90 degrees after the line-by-line delay. This is switched by the 25Hz head pulse.