System for indicating frequency of station signal received by superheterodyne radio receiver

Abstract

In a station signal frequency indicating system for a superheterodyne radio receiver, a station-signal frequency received by the receiver is evaluated on the basis of the oscillating frequency of a local oscillator in the receiver, the evaluation being compensated for a difference between the tuning frequency of the receiver and the station-signal frequency received. This evaluation is performed by, for instance, counting a signal generated at the local oscillator by a counter, and the compensation of evaluation is accomplished by, for example, varying a preset number for the counter in accordance with the dc-voltage level of the output of a demodulator in the receiver. Such system is capable of indicating a correct station-signal frequency so long as the frequency difference is less than a predetermined value, even when the receiver is not tuned exactly to the station-signal frequency.

Dependencies are inferred from the claim text.