PLL FREQUENCY SYNTHESIZER TYPE TV RECEIVER

摘要

PURPOSE:To confirm simply the AFT operation by providing a means changing forcibly the frequency dividing ratio of a programmable counter for confirming the operation of an AFT circuit. CONSTITUTION:When the test mode is transmitted to an N-value offset data generator 13, the generator 13 gives a signal to a channel data setting device 4 so that the frequency division ratio of a programmable counter 6 is 1/N frequency division offset to the standard channel data. Thus, the output frequency of a VCO7 is an offset frequency to the frequency of the standard channel. When a TV signal of the standard frequency is received in this state, an IF signal deviated by the offset frequency's share is obtained. Thus, the AFT circuit 1 is operated, the frequency division ratio of the counter 6 is changed, the output frequency of the VCO7 is moved and the PLL loop is operated so that the IF frequency is a correct frequency.