Radio receiver
AssigneeNippon Gakki Seizo Kabushiki Kaisha
InventorMinoru Ogita
Life of this patent
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Abstract
A radio receiver includes a phase-locked loop which is locked with the tuned frequency of a broadcast radio wave applied thereto, so that the output of the phase-locked loop is displayed by a display unit to display the tuned frequency. The displayed frequency is free from possible deviation of a local oscillation frequency from the tuned frequency.
Claims7
In a superheterodyne radio receiver having a radio frequency stage for receiving radio wave signals, an oscillator, a mixer stage coupled to said radio frequency stage and oscillator to provide intermediate frequency signals, and detector means for demodulating said intermediate frequency signals, the improvement comprising:
- a tuning circuit coupled to said radio frequency stage and responsive to a radio wave signal applied to said receiver and producing a signal of a tuned frequency equal to the frequency of said radio wave signal;
- a phase-locked loop circuit responsive to said tuned-frequency signal and producing an output signal having a frequency in accordance with said tuned frequency;
- means for varying a free-running frequency of said phase-locked loop circuit;
- means for varying the tuning frequency of said tuning circuit and interlocked with said free-running frequency varying means;
- and
- means for displaying the value of said output signal frequency of said phase-locked loop circuit.
A superheterodyne radio receiver comprising:
- (a) an antenna;
- (b) a tuning circuit responsive to a radio wave signal applied to said receiver through the antenna for providing a high-frequency signal of a tuning frequency equal to that of the radio wave signal and including means for varying the tuning frequency of said tuning circuit;
- (c) a local oscillator for producing a local oscillation frequency signal and including means for varying an oscillation frequency of said local oscillator;
- a mixer circuit connected to receive said high-frequency signal and said local oscillation frequency signal for converting said high-frequency signal into an intermediate-frequency signal;
- (d) a detector circuit for detecting said intermediate-frequency signal to produce an audio signal;
- (e) a phase-locked loop circuit connected to receive said high-frequency signal and including a voltage-controlled oscillator for producing an oscillatory output signal, a phase comparator responsive to said high-frequency signal and said output signal of said voltage-controlled oscillator to produce a signal representing a phase difference between both the signals, and a low-pass filter responsive to said phase difference signal for producing a control signal which is applied to said voltage-controlled oscillator for controlling the frequency of said output signal, said voltage-controlled oscillator including means for varying said free-running frequency, all of said tuning frequency varying means, said local oscillation frequency varying means and said free-running frequency varying means being interlocked with one another;
- and
- (f) an indicator coupled to said voltage-controlled oscillator for indicating the frequency of the output signal of the voltage-controlled oscillator.
Dependencies are inferred from the claim text.