Telecommunications – Receiver or analog modulated signal frequency converter – With wave collector
Reexamination Certificate
1999-05-12
2001-08-07
Bost, Dwayne (Department: 2681)
Telecommunications
Receiver or analog modulated signal frequency converter
With wave collector
C455S402000, C455S270000, C455S039000, C455S345000, C455S066100, C455S042000, C455S020000
Reexamination Certificate
active
06272328
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a system for providing audio signals from an auxiliary source to a radio receiver, particularly a vehicle radio receiver, using a DC power line such as a line connecting a cigarette lighter plug in a vehicle dashboard to the vehicle battery. The invention further relates to a system for automatically switching the input to a radio receiver from a radio broadcast signal to a signal from the auxiliary source.
BACKGROUND OF THE INVENTION
A number of systems exist which use an existing radio receiver (e.g., an AM and/or FM tuner in a vehicle) for playback of audio signals from an auxiliary source such as a compact disc (CD) player or a tape cassette player. For example, as disclosed in U.S. Pat. No. 4,712,250, to Michels et al, an adapter is provided to connect a portable stereo cassette player to a vehicle radio receiver. The adapter comprises a standard audio plug for receiving a signal from the cassette player. The adapter comprises circuitry (e.g., a tuning capacitor) for modulating the signal onto a weak FM carrier on an unused FM channel. The adapter can be inserted into a cigarette lighter receptacle to couple the FM signal to the radio.
Another system is disclosed in U.S. Pat. No. 5,448,757, to Hirata, in which the output of a CD player is FM-modulated for reception by an FM tuner. A radio frequency for modulating the output of the CD player is selected manually.
The devices disclosed in the two aforementioned patents are both disadvantageous for the same reason, that is, these devices require manual steps to play the audio signals from an auxiliary source on a radio receiver. A need exists for a device which allows an existing radio to automatically play an audio signal from an auxiliary source, instead of standard AM or FM broadcast programming, whenever the auxiliary source is present and operational.
In U.S. Pat. No. 3,751,601, to Wally, a tape playback device is provided for playing an audio signal from a tape cassette through a radio receiver in lieu of FM broadcast programming. A switch is provided for automatically switching between a radio broadcast station and a tape cassette source. The switch is mechanically activated when a tape is inserted into the tape playback device. This device, however, does not directly detect the presence of a signal from the auxiliary source. A need therefore exists for a device which detects when an audio signal from auxiliary source is present to provide the audio signal through a tuner. A need also exists for such a device which does not require activation by a user such as manual tuning or insertion of a tape or cassette into a playback device.
SUMMARY OF THE INVENTION
In accordance with the present invention, a device is provided for detecting the presence of a modulated audio signal from an auxiliary source, and for automatically operating a switch to provide the modulated audio signal to a tuner in lieu of the radio frequency signal received at the tuner antenna.
In accordance with an aspect of the present invention, the audio signal is frequency modulated on a channel in the operating radio frequency band of the tuner.
In accordance with another aspect of the present invention, the tuner is a vehicle tuner. The device comprises a modulator device having an output plug that is inserted into a cigarette lighter receptacle or power receptacle in the dashboard of the vehicle. An antenna switch unit is also provided and comprises a first input for connection to the vehicle antenna and an output for connection to the tuner antenna input. The antenna switch unit comprises a second input for receiving the output from the modulator device and a radio frequency signal detection device for detecting when a signal is provided to the second input. The antenna switch unit includes a switch connected to the first and second inputs to provide the signal at one of the inputs to the output. The antenna switch unit is therefore operable to provide the output from the modulator device to the tuner whenever the presence of a signal from the modulator device is detected.
In accordance with yet another aspect of the present invention, the cigarette lighter receptacle or power receptacle is connected to the antenna switch device via a radio frequency conductor such as a coaxial cable. The coaxial cable has two concentric conductors connected, respectively, to the positive and negative terminals of the cigarette lighter or power receptacle and to the vehicle battery or other DC power source. Thus, both DC power and modulated signals from an auxiliary source are provided to the antenna switch unit via a single conductor connected between the cigarette lighter or power receptacle in the dashboard of the vehicle, the vehicle battery and the antenna switch unit. The antenna switch unit allows the modulated signals to be on any frequency without concern for interference by nearby broadcast stations.
REFERENCES:
patent: 3369078 (1968-02-01), Stradley
patent: 3400221 (1968-09-01), Wolters
patent: 3665310 (1972-05-01), Tweed, Jr.
patent: 3751601 (1973-08-01), Wally
patent: 4712250 (1987-12-01), Michels et al.
patent: 5235568 (1993-08-01), Masaru
patent: 5319716 (1994-06-01), McGreevy
patent: 5448757 (1995-09-01), Hirata
patent: 5794138 (1998-08-01), Briskman
patent: 5797088 (1998-08-01), Stamegna
patent: 5867794 (1999-02-01), Hayes et al.
patent: 5903850 (1999-02-01), Huttunen et al.
patent: 0949771 (1999-10-01), None
Chatzipetros Argyrios A.
Nguyen Anh
Bost Dwayne
Persino Raymond
Roylance Abrams Berdo & Goodman
XM Satellite Radio Inc.
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