Electrical audio signal processing systems and devices – Binaural and stereophonic – Broadcast or multiplex stereo
Reexamination Certificate
1997-04-15
2001-03-06
Chang, Vivian (Department: 2747)
Electrical audio signal processing systems and devices
Binaural and stereophonic
Broadcast or multiplex stereo
Reexamination Certificate
active
06198825
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to wireless speaker systems; and, more particularly, it relates to a 900 MHz Wireless Speaker System.
Traditional wireless speaker systems have problems associated with tuning systems that cause drift, and are not truly wireless in that they use hardwired AC power sources to drive speakers in the system. Further, prior art speaker systems have the drawback of using fixed frequency downconverters. Hence, there exists a need for a wireless speaker system that eliminates or reduces the problems in the prior art speaker systems and does not utilize fixed frequency downconverters. Exemplary speaker systems having the drawbacks described above are illustrated in the U.S. Pat. Nos. 5,272,525 and 5,410,735. It is an object of the present invention to solve the problems in the art.
SUMMARY OF THE INVENTION
The present invention provides a 900 MHz wireless speaker system that uses a phase lock loop system in conjunction with a microprocessor to perform a variable fequency down conversion scheme that locks onto the carrier frequency eliminating problems associated with drift of the carrier frequency. The present invention include a phase lock loop control circuitry, local oscillation frequency of the variable frequency downconverter, and downconversion beat frequency that is not fixed (but variable). Tuning of the present invention is accomplished in the variable setting on the phase lock loop system by a variable downconversion beat frequency. The design has the advantage of not requiring any tuning system on another circuit area.
The wireless speaker system of the present invention further utilizes a battery power source and/or alternating current power source, and provides for a remote control to control the various features on the speaker. Other features of the invention include a wireless transmitter, an antenna, and a wireless frequency modulated receiver.
The objects and features of the present invention, other than those specifically set forth above, will become apparent in the detailed description of the invention set forth below.
REFERENCES:
patent: 4388496 (1983-06-01), Miyamoto
patent: 4847903 (1989-07-01), Schotz
patent: 4899388 (1990-02-01), Mlodzikowski et al.
patent: 5038402 (1991-08-01), Robbins
Chang Vivian
Michael Best & Friedrich
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