Abstract: An AFC circuit for a television receiver capable of unambiguous operation with substantially offset signal frequencies has a response characteristic defined by a positive portion intermediate a pair of substantially equally sized negative portions. The circuit includes a multiplier with an unbalanced coupling between the limiter and the discriminator which has a single adjustable tuned circuit nominally tuned to 45.75 MHz.

Abstract: A "walking circuit" for modifying the IF frequency response of a television receiver is disclosed. The walking circuit includes an amplifier having a pair of selectable gain-degeneration impedances, one such impedance providing the amplifier with a wide band frequency response and the other providing the amplifier with a frequency sensitive response whose peak is centered at the IF frequency of the picture carrier. A current-steering circuit, responsive to the level of the signal received by the receiver, selects the wide band degeneration impedance by steering current through it when high level signals are received so that the amplifier does not modify the IF frequency response. When low level signals are received, current is steered through the frequency sensitive degeneration impedance for modifying the IF frequency response such that maximum gain occurs at or near the IF frequency of the picture carrier.