Data and voice communications system
First Claim
1. In a communication system for communication of digital data information on the same communications medium as analog transmissions, at frequencies greater than the analog transmission, and where crosstalk interference with other signals is possible, the improvement comprising:
- means for time compressing multiple bit blocks of the digital data information so that the frequency rate of the digital data signal transmitted is greater than the frequencies of the analog signal;
means for spreading the energy of the time compressed digital data signal over a spectrum of frequencies, all greater than the frequencies of the analog signal, so that crosstalk interference with other signals is minimized;
means for coupling the digital data signal to the communications medium so that the spectrum of frequencies can be transmitted simultaneously with the analog signal at data transmission frequencies greater than the frequencies of analog signal; and
means for isolating the spectrum of time compressed digital data signal frequencies from the frequencies of the analog signal so that the high frequency data signal does not interfere with the analog transmission.
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Accused Products
Abstract
A high speed and relatively error free communications system is disclosed which enables the high speed transmission of data at a 19.2 kilobit per second rate. The data is transmitted over the same communications medium as voice transmissions, the data transmission being virtually imperceptible to the user of the analog telephone system. Connection to and from the data terminals is made through an RS232C interface. A spread spectrum technique is utilized which "whitens" the signals of the data terminal regardless of whether the terminal is idle, transmitting or receiving data. Virtual error free transmission is achieved by interleaving bits, so that noise does not destroy the data, and by error detection and correction techniques which assure that the data, as received, is identical to that transmitted. By using a variable pseudo random code, privacy of data communications are enhanced and cross-talk is substantially eliminated. The resulting system is one that can use a single twisted pair wire for transmission and is capable of transmitting data at a high rate of speed while leaving the analog voice transmission resident and unaffected on the line.
555 Citations
53 Claims
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1. In a communication system for communication of digital data information on the same communications medium as analog transmissions, at frequencies greater than the analog transmission, and where crosstalk interference with other signals is possible, the improvement comprising:
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means for time compressing multiple bit blocks of the digital data information so that the frequency rate of the digital data signal transmitted is greater than the frequencies of the analog signal; means for spreading the energy of the time compressed digital data signal over a spectrum of frequencies, all greater than the frequencies of the analog signal, so that crosstalk interference with other signals is minimized; means for coupling the digital data signal to the communications medium so that the spectrum of frequencies can be transmitted simultaneously with the analog signal at data transmission frequencies greater than the frequencies of analog signal; and means for isolating the spectrum of time compressed digital data signal frequencies from the frequencies of the analog signal so that the high frequency data signal does not interfere with the analog transmission. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. In a method for communication of digital data information on the same communications medium as analog transmissions, at frequencies greater than the analog transmission, and where crosstalk interference with other signals is possible, the improvement comprising:
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time compressing multiple bit blocks of the digital data information so that the frequency rate of the digital data signal transmitted is greater than the frequencies of the analog signal; spreading the spectral energy of the digital data signal over a spectrum of frequencies greater than the frequencies of the analog signal so that crosstalk interference with other signals is minimized; coupling the digital data signal to the communications medium so it can be transmitted simultaneously with the analog signal; and isolating the digital data signal from the analog signal so that the high frequency data signal does not interfere with the analog transmission. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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Specification