Radio receiver

Abstract

A radio receiver includes a noise blanking system comprising a switching circuit in the signal path which is responsive to a blanking signal for preventing passage of signals. A blanking signal producing circuit is in the signal path ahead of the switching circuit and is responsive to predetermined noise signals received by the radio receiver for producing the blanking signal. The receiver also includes an AGC circuit for producing a gain control signal and a signal strength meter coupled for response to the gain control signal. A linearity control system comprises a current controlling circuit responsive to a meter control signal for controlling the current flow through the meter so as to increase the range of linear response of the meter. A signalling circuit is coupled with the AGC circuit and with the current controlling circuit and is responsive to the gain control signal for producing the meter control signal. A tuning system for the receiver comprises a first local oscillator responsive to first oscillator control signals for varying the frequency of first oscillator signals over a first range at first increments. A second local oscillator normally produces a second oscillator signal at a fixed frequency. A frequency varying circuit is coupled with the second oscillator and responsive to second oscillator control signals for varying the frequency of the second oscillator signals over a second range at second increments which are smaller than the first increments. A control circuit produces the first and second oscillator control signals.