TELEVISION PICTURE RECEIVER

摘要

PURPOSE:To simplify the circuit constitution by making one reference oscillator double the PLL channel selection, the local oscillation and the video detecting oscillation each. CONSTITUTION:The output of reference oscillator 18 is applied to dividers 20 and 19. The division ratio of divider 19 can be varied by the indication given from channel selector 21 to be used the input to mixer 15 for obtaining the necessary IF frequency to the reception channel. While divider 20 features a fixed division ratio with its output frequency matched to the IF frequency. Then the video signal is obtained by having the synchronous detection with the division output. Phase control circuits 22 and 23 control divider 19 in case the transmission frequency gets out of position to keep the frequency at the normal IF frequency.