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WIRELESS STEREO SOUND SPEAKER SYSTEM AND MODULATOR-OSCILLATOR CIRCUIT

  • US 3,590,382 A
  • Filed: 12/20/1967
  • Issued: 06/29/1971
  • Est. Priority Date: 12/20/1967
  • Status: Expired due to Term
First Claim
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1. A wireless stereo sound speaker system comprising:

  • a first FM transmitter including first input terminals for supplying recorded electric stereo signals from a first sound track, a first coupling transformer receiving the first track stereo signal and having a primary and secondary winding with a common terminal, first modulator-oscillator circuit coupled to said first coupling transformer for frequency modulating a radio frequency carrier signal produced in a tank with said first track stereo signal and radiating the resulting modulated carrier signal as wave energy along a first channel; and

    a second FM transmitter including second input terminals for supplying the recorded electric stereo signal from a second sound track, a second coupling transformer receiving the second track stereo signal and having a primary and a secondary winding with a common terminal, and a second modulator-oscillator circuit coupled to said second coupling transformer for frequency modulating a second radio frequency carrier signal at a different frequency from said first carrier signal with said second track stereo signal and radiating the resulting second modulated carrier signal as wave energy along a second channel simultaneously with said first transmitter, each said modulator-oscillator circuit including a parallel connected inductor-capacitor tank and a feedback capacitor having a pair of plates connected in series with the tank, said tank being connected to one side of said secondary winding and a transistor oscillator connected in a common-base configuration, said transistor having emitter, base and collector electrodes, one of said plates being connected to said collector and the other of said plates to said emitter, said base being coupled to said common terminal to apply the modulating signals to said base; and

    first and second receiver at a location remote from said first and second transmitters, said first receiver being tuned to said first carrier signal frequency for reproducing stereophonic sounds from the electric stereo signals transmitted from said first transmitter and said second receiver at a selected spaced distance from the first receiver being tuned to the carrier frequency of said second transmitter for reproducing audible stereophonic sounds from the electric stereo signals transmitted from said second transmitter, each said first and second receivers having an intensity control to provide a phase balance in the sound being reproduced by said receivers at a listener'"'"''"'"'s ears.

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