Channel selector having a plurality of tuning systems
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorYoichi Sakamoto
Life of this patent
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Abstract
A channel selector characterized in that a plurality of receivers capable of simultaneously performing a receiving operation have a main part of a phase-locked loop frequency synthesizer connected in common thereto, the frequency synthesizer having a programmable frequency divider, a phase comparator, a reference oscillator and a reference frequency divider. The frequency synthesizer is controlled so that a local oscillation frequency corresponding to a determined frequency close to a broadcast signal of a desired receiving channel is synthesized, and one of a plurality of search tuning systems searches and tunes the broadcast signal from the local oscillation frequency.
Claims9
A channel selector for controlling the tuning frequency of a plurality of receivers capable of simultaneously performing receiving operations, each of said plurality of receivers having a portion of a phase-locked loop frequency synthesizer;
- wherein another portion of a phase-locked loop frequency synthesizer is commonly used by said portions of said synthesizers whereby each of said plurality of receivers has an equivalent complete phase-locked loop frequency synthesizer;
- and wherein each of said plurality of receivers has its own low pass filter included in its equivalent phase-locked loop frequency synthesizer, and an output of a phase comparator is switched to an input terminal of one low pass filter from among said plurality of low pass filters by a 3-state switching circuit.
A channel selector for controlling the tuning frequency of a plurality of receivers capable of simultaneously performing receiving operations, each of said plurality of receivers having a portion of a phase-locked loop frequency synthesizer;
- wherein another portion of a phase-locked loop frequency synthesizer is commonly used by said portions of said synthesizers whereby each of said plurality of receivers has an equivalent complete phase-locked loop frequency synthesizer;
- and wherein each of said equivalent phase-locked loop frequency synthesizers is controlled so that a local oscillation frequency corresponding to a predetermined frequency close to a broadcast signal of a desired receiving channel is synthesized, and one of a plurality of search tuning systems searches and tunes said broadcast signal from said local oscillation frequency whereby said broadcast signal of said desired receiving channel is tuned.
A channel selector for controlling the tuning frequency of a plurality of receivers capable of simultaneously performing receiving operations, each of said plurality of receivers having a portion of a phase-locked loop frequency synthesizer;
- wherein another portion of a phase-locked loop frequency synthesizer is commonly used by said portions of said synthesizers whereby each of said plurality of receivers has an equivalent complete phase-locked loop frequency synthesizer;
- and wherein each of said phase-locked loop frequency synthesizers selects a desired receiving channel, and wherein a tuning voltage of said desired receiving channel is stored in a voltage memory means, and wherein said channel selector further comprises a tuning means provided for each of said plurality of receivers so that while receiving, said tuning means tunes in accordance with the output of said voltage memory means.
Dependencies are inferred from the claim text.