Radio receiver
First Claim
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1. A receiver, comprising:
- a phase-locked loop circuit including a voltage-controlled oscillator, a variable frequency divider for frequency-dividing an output of said voltage-controlled oscillator, a reference oscillator, a phase detector for outputting a phase difference signal representing a phase difference between an output of said variable frequency divider and an output of said reference oscillator, and a filter for smoothing an output voltage of said phase detector, with a resultant voltage of said filter used as a control voltage fed to said voltage-controlled oscillator;
a reception unit, tuned to a frequency corresponding to an oscillation frequency of said voltage-controlled oscillator, for receiving a signal having the oscillation frequency of said voltage-controlled oscillator;
control voltage measuring means for measuring the control voltage supplied to said voltage-controlled oscillator and for measuring a voltage of an output signal of said reception unit that corresponds to the tuned frequency of said reception unit; and
control means for producing a signal that has a voltage value measured by said control voltage measuring means and supplying the signal to said voltage-controlled oscillator when the oscillation frequency of said phase-locked loop circuit is stabilized and said phased-locked loop is open, wherein said control means further controls said control voltage measuring means to measure a center voltage of the output signal from said reception unit for correcting the voltage value of the produced signal according to a frequency shift when a shift in the tuned frequency of said reception unit is detected by comparing the measured center voltage to an initial center voltage measured when said phase-locked loop circuit is first stabilized.
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Abstract
A frequency synthesizer type receiver requiring small power consumption and maintaining excellent receiving performance. In the frequency synthesizer type receiver, a reception frequency thereof is set based on an oscillatory output of a PLL circuit. When the oscillation frequency of the PLL circuit is stabilized, a control voltage can be supplied to a voltage-controlled oscillator in the PLL circuit from a controller situated outside of the PLL circuit. The tuned state of a reception unit is measured at this time. If a shift in the reception frequency is detected based on the measured value, the control voltage to be supplied to the voltage-controlled oscillator is corrected.
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Citations
1 Claim
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1. A receiver, comprising:
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a phase-locked loop circuit including a voltage-controlled oscillator, a variable frequency divider for frequency-dividing an output of said voltage-controlled oscillator, a reference oscillator, a phase detector for outputting a phase difference signal representing a phase difference between an output of said variable frequency divider and an output of said reference oscillator, and a filter for smoothing an output voltage of said phase detector, with a resultant voltage of said filter used as a control voltage fed to said voltage-controlled oscillator;
a reception unit, tuned to a frequency corresponding to an oscillation frequency of said voltage-controlled oscillator, for receiving a signal having the oscillation frequency of said voltage-controlled oscillator;
control voltage measuring means for measuring the control voltage supplied to said voltage-controlled oscillator and for measuring a voltage of an output signal of said reception unit that corresponds to the tuned frequency of said reception unit; and
control means for producing a signal that has a voltage value measured by said control voltage measuring means and supplying the signal to said voltage-controlled oscillator when the oscillation frequency of said phase-locked loop circuit is stabilized and said phased-locked loop is open, wherein said control means further controls said control voltage measuring means to measure a center voltage of the output signal from said reception unit for correcting the voltage value of the produced signal according to a frequency shift when a shift in the tuned frequency of said reception unit is detected by comparing the measured center voltage to an initial center voltage measured when said phase-locked loop circuit is first stabilized.
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Specification