SIMULTANEOUS TRANSMISSION OF A VIDEO AND AN AUDIO SIGNAL THROUGH AN ORDINARY TELEPHONE TRANSMISSION LINE

• US 3,873,771 A
• Filed: 04/11/1972
• Issued: 03/25/1975
• Est. Priority Date: 04/11/1972
• Status: Expired due to Term

• Current Assignee: Ben Kleinerman, Meyer J. Geist
• Original Assignee: Ben Kleinerman, Meyer J. Geist
• Inventors: Kleinerman, Ben, Geist, Meyer J.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/242,946
• Time in Patent Office: 1,078 Days
• Field of Search: 179/2TV,15BT,15FD,2DP,15.55,2.5,3,4,15BM 178/5.6,5.8,DIG.3,DIG.7,DIG.23,35 325/47,48,51,57 343/200,207
• US Class Current: 370/204
• CPC Class Codes: H04J 9/00 Multiplex systems in which each channel is represented by a different type of modulation of the carrier
• CPC Class Codes: H04N 7/12 Systems in which the television signal is transmitted via one channel or a plurality of parallel channels, the bandwidth of each channel being less than the bandwidth of the television signal H04N7/24 takes precedence
• CPC Class Codes: H04N 7/148 Interfacing a video terminal to a particular transmission medium, e.g. ISDN

Abstract

A communication system for simultaneously transmitting a video and audio signal through the same transmission line. The transmission line can be a standard telephone line, and the video signal can be transmitted by FM slow scan TV techniques, while the audio signal can be transmitted by AM single sideband techniques. Simultaneous transmission of video and voice is accomplished over the same transmission line by separating the AM signal and FM signal into separate channels, and since AM reception is relatively insensitive to FM, and FM reception is relatively insensitive to AM, the signals do not interfere with one another.

Claims

1. A communication system for transmitting information through a telephone transmission line having a finite bandwidth of from 0 to 4,000 Hz, said bandwidth having two adjacent but separated segments, one extending over a lower frequency range than the second which extends over a higher frequency range, said system comprising:

a. means for transmitting an FM slow scan video signal through said transmission line in the second frequency range, b. means for simultaneously transmitting an audio signal through said transmission line in said one frequency range, c. the upper end of the lower segment being adjacent but spaced from the lower end of the upper segment, whereby said audio and FM signals are free of interference from one another, d. means for receiving said FM slow scan video signal from said telephone transmission line coupled to said telephone transmission line and the output of said FM slow scan video transmitting means, e. means for receiving said audio signal from said telephone transmission line coupled to said telephone transmission line and the output of said audio transmitting means, f. a switch for disconnecting the output of said FM slow scan video transmitting means from said FM slow scan video receiving means and said telephone transmission line, g. said audio transmitting means being always connected to said audio receiving means and said telephone transmission line, h. a second audio transmitting means in the physical vicinity of the FM slow scan video receiving means, i. a second audio receiving means in the physical vicinity of the first-named audio transmitting means, j. a second means for transmitting an F-M slow scan video signal through said transmission line in the second frequency range located in the physical vicinity of the second audio transmitting means, k. a second means for receiving an FM slow scan video signal from said telephone transmission line coupled to said telephone transmission line and the output of said second FM slow scan video signal transmitting means, said second FM receiving means located in the physical vicinity of said second audio receiving means, l. a switch for disconnecting the output of the second FM slow scan video transmitting means from said second FM slow scan video receiving means and said telephone transmission line, m. said second audio transmitting means and said second audio receiving means being connected to said telephone transmission line for transmitting an audio signal through said line over said one frequency range so that simultaneous voice communication in both directions through said telephone ne transmission line is possible, n. whereby said switches ensure slow scan of video communication through said telephone transmission line in one direction only at a given time.