# US 5,349,386 A · Wireless signal transmission systems, methods and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,349,386 A - Document ID: US5349386A - Status: Granted - Kind: A - Application number: 07/982,889 - Filed: 1992-11-30 - Granted: 1994-09-20 - Earliest claimed: 1991-03-07 - Assignees: Recoton Corporation - Inventors: Robert L. Borchardt; William T. McGreevy; Ashok Nawarange; Efrain L. Rodriguez - Web page: https://patentgrep.com/patent/US5349386A ## CPC - H04B 1/0096: {where a full band is frequency converted into another full band} - H04B 1/18: Input circuits, e.g. for coupling to an antenna or a transmission line (coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H) - H04B 1/26: for superheterodyne receivers (multiple frequency-changing H03D7/16) - H04N 5/38: Transmitter circuitry {for the transmission of television signals according to analogue transmission standards} (H04N5/14 takes precedence) - H04R 5/033: Headphones for stereophonic communication {(details thereof, e.g. relating to batteries, cables or control elements H04R1/10)} - H04R 1/1025: Accumulators specially adapted for earpieces; Arrangements specially adapted for charging thereof - H04R 2420/07: Applications of wireless loudspeakers or wireless microphones - H04B: TRANSMISSION - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract A transmission apparatus and method for transmitting stereo multiplexed audio signals from a received television signal having a horizontal frequency f.sub.H are provided. Right and left channel audio signals obtained by demodulation from the received television signal are added to form a first combined audio signal. The same signals are subtracted to form a second combined audio signal. A subcarrier is modulated with one of the first and second combined audio signals, the subcarrier having a frequency substantially equal to 3f.sub.H to form a subcarrier modulated audio signal. The other of the first and second combined audio signals is combined with the subcarrier suppressed signal to form a stereo multiplexed audio signal, and the stereo multiplexed audio signal is transmitted. ## Claims ### Claim 1 A method of transmitting stereo multiplexed audio signals from a received television signal having a horizontal frequency f.sub.H, comprising the steps of: receiving right and left channel audio signals obtained by demodulation from the received television signal; adding the right and left channel audio signals to form a first combined audio signal; subtracting the right and left channel audio signals to form a second combined audio signal; modulating a subcarrier with one of the first and second combined audio signals, the subcarrier having a frequency substantially equal to 3f.sub.H to form a subcarrier modulated audio signal; combining the other of the first and second combined audio signals with the subcarrier modulated audio signal to form a stereo multiplexed audio signal; and transmitting the stereo multiplexed audio signal. ### Claim 2 (depends on 1) The method of claim 1, wherein the step of transmitting the stereo multiplexed audio signal comprises frequency modulating a radio frequency carrier with said stereo multiplexed audio signal to form a modulated radio frequency carrier signal, and wirelessly transmitting the modulated radio frequency carrier signal. ### Claim 3 (depends on 2) The method of claim 2, wherein the step of frequency modulating the radio frequency carrier comprises frequency modulating a radio frequency carrier having a frequency above 900 MHz to form a local transmission signal, and the step of wirelessly transmitting the radio frequency carrier signal comprises wirelessly transmitting the local transmission signal within a local transmission area. ### Claim 4 (depends on 3) The method of claim 3, further comprising the step of receiving the local transmission signal within the local transmission area using a personal wireless receiver unit carried on the person of a listener. ### Claim 5 A transmitter apparatus for transmitting stereo multiplexed audio signals from a received television signal having a horizontal frequency f.sub.H, comprising: input means for receiving right and left channel audio signals obtained by demodulation from the received television signal; means for adding the right and left channel audio signals to form a first combined audio signal; means for subtracting the right and left channel audio signals to form a second combined audio signal; means for modulating a subcarrier with one of the first and second combined audio signals, the subcarrier having a frequency substantially equal to 3f.sub.H to form a subcarrier modulated signal; means for combining the other of the first and second combined audio signals with the subcarrier modulated signal to form a stereo multiplexed audio signal; and transmitter means for transmitting the stereo multiplexed audio signal. ### Claim 6 (depends on 5) The transmitter apparatus of claim 5, wherein the transmitter means comprises frequency modulation means for frequency modulating a radio frequency carrier with said stereo multiplexed audio signal to form a modulated radio frequency carrier signal, and wireless transmitter means for wirelessly transmitting the modulated radio frequency carrier signal. ### Claim 7 (depends on 6) The transmitter apparatus of claim 6, wherein the frequency modulation means is operative to modulate a radio frequency carrier having a frequency above 900 MHz to form a local transmission signal, and the wireless transmitter means is operative to transmit the local transmission signal within a local transmission area. ### Claim 8 (depends on 5) The transmitter apparatus of claim 5, further comprising low pass filter means for attenuating noise in the right and left channel audio signals at a frequency equal to a television horizontal synchronization frequency and means for selectively enabling said low pass filtering means.