Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Patent
1979-09-24
1982-09-07
Bookbinder, Marc E.
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
455169, 455182, 455192, H03J 726, H04B 126
Patent
active
043487700
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention concerns a channel selection apparatus adapted to facilitate manual channel selection in electronic tuning radio receivers.
BACKGROUND OF THE INVENTION
Electronic channel selection can be attained using voltage-variable type reactance elements in tuning circuits of a radio receiver and providing a control voltage generation circuit therefor. The channel selection can be realized such as by a search channel selection system adapted to sweep the entire receiving frequency band from one direction or another direction (specifically, by the changes in a control voltage), stop the sweeping when a broadcasting station is caught and enter into receiving as it is if the station is a desired one or start the sweeping again by the push of a pushbutton if the station is not a desired one. A digital channel selection system is adapted to set the frequency for a desired broadcasting station previously in a digital manner and change the receiving frequency as far as the receiving frequency reaches the set frequency, or a manual channel selection system is adapted to manually maintain the gradual increase or decrease in a control voltage till a desired broadcasting station is caught. The applicant has already proposed various types of channel selection apparatus such as "Digital Setting Receiver" in Japanese Patent Application No. 39648/1976, "Automatic Channel Selection Apparatus" in Japanese Patent Application No. 40024/1976 and "Electronic Tuning Radio Receiver" in Japanese Patent Application No. 129831/1976.
This invention concerns, among the above systems, a manual channel selection system, which is adapted to facilitate the channel selecting operation. The manual channel selection in the prior system is adapted to perform the channel selection by gradually increasing or decreasing the control voltage, in order to identify, upon reception of a broadcasting wave, if it is a desired broadcasting station or not by listening to it or observing the indication on a dial and enter into receiving state if it is a desired one by interrupting the changes in the control voltage. The station is passed momentarily in a frequency band where broadcasting stations are densely populated thus causing difficulty in the channel selection, since the channel selection speed, although relatively slow, is such a rate as sweeping the full scale in about 20-30 seconds, that is, 5-6 stations per one second in an AM band (10 KHz intervals between each of the stations).
SUMMARY OF THE INVENTION
It is, accordingly, an object of this invention to interrupt the sweeping operation temporarily when a broadcasting wave is received thereby providing a sufficient time to determine whether the broadcasting wave, that is, the broadcasting station is a desired one or not.
Another object of this invention is to enable a clear listening to the broadcasting by the fine control of a control voltage with an AFC voltage during interruption of the sweeping.
According to this invention, a gate circuit is provided for the control of an input signal to a voltage source which supplies a bias voltage to variable reactance elements in an electronic tuning radio receiver and, upon reception of a broadcasting wave, an input signal from a manual channel selection switch is temporarily interrupted and, instead, an AFC signal is inputted. This interrupts the frequency sweeping to enable a radio audience to clearly hear the broadcasting and judge whether it is a desired one or not.
Other objects, constitutions and advantages of this invention will be made clearer by the following descriptions referring to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram showing an embodiment of this invention,
FIG. 2 is a waveform chart showing examples of signal waveforms in each of the sections in FIG. 1, and
FIG. 3 is a waveform chart for the output voltage from a bias voltage source.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1, there is shown a receiving antenna 10, a hig
REFERENCES:
patent: 3467870 (1966-01-01), Aoyama
patent: 3821650 (1974-06-01), Kase et al.
patent: 3968441 (1976-07-01), Garskamp
patent: 4053838 (1977-10-01), Amaya
patent: 4240115 (1980-12-01), Kamiya
Bookbinder Marc E.
Fujitsu-Ten, Ltd.
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