AUTOMATIC TRACKING COMPENSATION CIRCUIT FOR ELECTRONIC TUNER

摘要

PURPOSE:To ensure control for the bias voltage and then correct the tracking error of a receiver, by varying the vias voltage applied to the variable capacity diode of a tuning element and thus detecting the best tuning frequency. CONSTITUTION:A variable capacity diode is used for the tuning element of the antenna tuning circuit 2 and the high-frequency tuning circuit 3' respectively. The intermediate frequency signal is detected 22 and receives the wave detection 24 for the intermeidate frequency amplifier circuit 5 of a receiver having such constitution as mentioned above, thus obtaining a DC output. The maximum value of the DC output is detected, and the level of the output is kept at 25. Then the signal of the peak level holding means 25 is compared at 27 with the DC output with respect to their levels to obtain a control signal. The bias voltage of the variable diode is varied at 14 by the signal supppied from the channel selection control means 13, and the working of the voltage varying means 14 is controlled by the control signal.