Simultaneous transmission of two information signals within a band-limited communications channel
First Claim
1. A co-channel communications system for transmitting at least one digital data signal simultaneously with a communications medium signal comprising:
- means for generating a plurality of spreading frequencies;
means for combining the data signal and the plurality of spreading frequencies which causes each logic level of the data signal to be transmitted as a multifrequency signal consisting of a separate set of frequencies, each set being spread throughout the bandwidth of the communications medium channel, each of said multifrequency signals having a signal amplitude at a level which is substantially suppressed in relation to the magnitude of the communications medium signal at the signal to signal ratio which is at a non-interfering level and which is a function of the number of frequencies used for transmission of the data signal; and
means for connecting the resulting multifrequency signal to the communications medium for simultaneous transmission with the communication medium signal.
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Accused Products
Abstract
A co-channel communications system is disclosed which permits a digital data signal to be simultaneously transmitted with a communications medium signal such as telephone voice or television video. The data signal or signals are converted into very low multifrequency signals consisting of fundamental frequencies and harmonics which span the communications bandwidth. Because a number of frequencies are used for each data signal, the signal level of the data signals can be greatly suppressed relative to the communications medium signal to a level such that there is no perceptible degradation of the telephone voice or television video. Synchronous detectors for each frequency transmitted, including harmonic frequencies, are utilized to recapture and regenerate the data signals transmitted.
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Citations
23 Claims
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1. A co-channel communications system for transmitting at least one digital data signal simultaneously with a communications medium signal comprising:
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means for generating a plurality of spreading frequencies; means for combining the data signal and the plurality of spreading frequencies which causes each logic level of the data signal to be transmitted as a multifrequency signal consisting of a separate set of frequencies, each set being spread throughout the bandwidth of the communications medium channel, each of said multifrequency signals having a signal amplitude at a level which is substantially suppressed in relation to the magnitude of the communications medium signal at the signal to signal ratio which is at a non-interfering level and which is a function of the number of frequencies used for transmission of the data signal; and means for connecting the resulting multifrequency signal to the communications medium for simultaneous transmission with the communication medium signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for simultaneously transmitting at least one digital data signal with a communications medium signal transmitted on a communications medium comprising the steps of:
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generating a plurality of spreading frequencies; combining the data signal and the plurality of spreading frequencies so that a first logic level of the data signal is transmitted as a multifrequency signal consisting of a first set of frequencies and a second logic level of the data signal is transmitted as a multifrequency signal consisting of a second set of frequencies; and transmitting the resulting multifrequency signals on the same communications medium as the communications medium signal, but at a suppressed level relative to the communications medium signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification