Electronic tuning system for radio receivers, with digital memorization of the signal frequency

Claim 1

A circuit for generating and digitally storing control voltage signals for application to electronic tuning circuitry of an electronically tuned radio receiver comprising manual control means for generating a first control voltage; a clock pulse generator; counter means for counting clock pulses from said clock pulse generator; a digital-to-analog converter coupled to said counter means and adapted to supply a second control voltage, indicative of the number of clock pulses counted by said counter means, to electronic tuning circuitry of an electronically tuned radio receiver; a voltage comparator having a first input, a second input, and an output; the output from said converter being connected to the first input of said voltage comparator; the second input of said voltage comparator being connected to said manual control means; a gate circuit coupling said clock pulse generator to said counter means; the output from said voltage comparator being connected to said gate circuit to discontinue the supply of said clock pulses to said counter means when the second control voltage is substantially equal to the first control voltage; and digital memory means coupled to the outputs from said counter means and to the inputs of said digital-to-analog converter and arranged to digitally store clock pulse count signals corresponding to control voltages associated with tuning frequencies of selected radio broadcasting stations.