Abstract: A dual rate bi-directional switching system is utilized to control a radio receiver function. An actuator rotates and translates in order to sequentially actuate selected electrical switches which are coupled to a logic circuit by means of two conductors. The logic circuit establishes logic signals to control both the direction and rate of change of the function in response to the position of the actuator.

Abstract: A zero crossing detector and one shot circuit connected to receive audio frequency signals from a receiver and provide a pulse each time the signal crosses a reference level, first and second one shot timers connected to receive the pulses and provide pulses in response thereto which coincide with the zero crossing of a predetermined signal it is desired to mute, coincidence gates receiving the one shot pulses and the delayed pulses and cooperating with a missing pulse detector and a relay in the receiver to mute the receiver whenever the pulses from either of the one shot timers coincide with the pulses from the zero crossing detector, which coincidence indicates a signal of the frequency it is desired to mute.