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4.A6机芯伴音信号流程(见图4) 由带通滤波器选出的第二伴音调频信号,经HEF4052切换,选出相应制式的第二伴音中频信号,从LA7688①脚用入。在LA7688内部经伴音中频限幅放大、PLL锁相环鉴频,取出音频信号。该音频信号通过放大和音频开关切换后,从LA7688(51)脚输出,送给TDA7496,在TDA7496中,音频信号经音量控制和功率放大,然后推动扬声器发出声音。 5.A6机芯扫描信号流程 A6机芯的扫描电路主要分为两大部分。其中扫描
4.A6 movement sound signal process (see Figure 4) by the band-pass filter selected by the second audio FM signal, the HEF4052 switch, select the appropriate standard for the second audio intermediate frequency signal from the LA7688 ① feet into. In the LA7688 by the IF intermediate frequency limiting amplification, PLL PLL frequency identification, remove the audio signal. The audio signal is amplified by the audio switch and output from the LA7688 (51) pin to the TDA7496. In the TDA7496, the audio signal is volume controlled and power amplified, and the speaker is then powered to sound. 5.A6 movement scanning signal flow A6 movement of the scanning circuit is divided into two parts. Which scan