Automatic channel selection apparatus
AssigneeHitachi, Ltd.
InventorsToshinori Murata, Shigeo Matsuura
Life of this patent
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Abstract
An automatic channel selection apparatus comprises an electronic tuner having a local oscillator an oscillation frequency of which is controlled by an applied voltage, a voltage sweep circuit for sweeping the voltage to be applied to the local oscillator, means for deriving from an output of the local oscillator, signals of different phases and combining those signals, a detector for envelope-detecting an output of the deriving means and means for counting the number of varying cycle periods in the output of the detector which changes periodically each time the oscillation frequency of the local oscillator changes by a given amount which is inversely proportional to the phase difference to change a tuning frequency of the electronic tuner by a specified amount.
Claims5
An automatic channel selection apparatus comprising:
- an electronic tuner having a local oscillator an oscillation frequency of which is controlled in accordance with an applied voltage;
- a voltage sweep circuit for sweeping the voltage to be applied to said local oscillator;
- means for deriving from an output of said local oscillator, signals of different phases and combining said signals;
- a detector for envelope-detecting an output of said meas;
- and
- means for counting the number of the output signals of said detector which changes periodically each time the oscillation frequency of said local oscillator changes by a given amount which is inversely proportional to the phase difference between said signals to stop the voltage sweep of said voltage sweep circuit when the count reaches a specified count.
An automatic channel selection apparatus comprising:
- an electronic tuner having a local oscillator an oscillation frequency of which is controlled in accordance with an applied voltage;
- a voltage sweep circuit for sweeping the voltage to be applied to said local oscillator;
- means for deriving from an output of said local oscillator, signals of different phases and combining said signals;
- a detector for detecting a combined signal from said means to produce a signal which changes at a cycle period which is inversely proportional to the phase difference between said signals;
- a channel number entry device;
- a counter for counting up the output of said detector by the number corresponding to a channel number entered by said channel number entry device and producing an end of count signal when the counting operation is completed;
- and
- means responsive to said end of count signal from said counter for stopping the voltage sweep of said voltage sweep circuit.
Dependencies are inferred from the claim text.