Multiple signal transmission method and system, particularly for television
First Claim
1. A method for secure transmission of plural audio signals, comprising the steps of:
- providing at least two different audio signals;
transmitting in a first form within a predetermined frequency band one and then the other of the audio signals in a sequence of time intervals such that parts but not all of each of the two audio signals are transmitted in said frequency band in the first form;
transmitting within said frequency band, in a second form distinguishable from said first form, one and then the other of the audio signals in said sequence of time intervals such that the one of the audio signals is transmitted in a time interval in the second form while the other is being transmitted in a time interval of corresponding length in the first form and vice-versa, parts of the one and the other audio signals not transmitted in the first form thereby being transmitted in the second form so that the two audio signals are transmitted in their entireties in said frequency band but are transmitted in part in the first form and in part in the second form, both of the two audio signals being available in the transmitted signal for selection in their entireties from said first and second forms.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and system for scrambling a plurality of input signals for secure transmission thereof, as well as various methods and systems for television transmission, are disclosed. The disclosed scrambling technique, in one form, includes modulating an in-phase component of at least one carrier signal in response to one and then another of a plurality of input signals in a sequence of time intervals such that parts but not all of the one and another of the input signals are carried by the in-phase component. A quadrature component of the at least one carrier signal is modulated in response to the one and another of the plurality of input signals in the sequence of time intervals such that parts but not all of the one and another of the input signals are carried by the quadrature component and such that the in-phase and quadrature components together carry the one and another of the input signals in their entireties. The modulated in-phase and quadrature components are combined for transmission. A decoder for unscrambling the plurality of signals is also disclosed. The various television transmission methods and systems involve provision of additional audio signals, in scrambled or unscrambled form, with the normal television audio and video signals so that multi-lingual program service as well as other services can be provided.
140 Citations
20 Claims
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1. A method for secure transmission of plural audio signals, comprising the steps of:
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providing at least two different audio signals; transmitting in a first form within a predetermined frequency band one and then the other of the audio signals in a sequence of time intervals such that parts but not all of each of the two audio signals are transmitted in said frequency band in the first form; transmitting within said frequency band, in a second form distinguishable from said first form, one and then the other of the audio signals in said sequence of time intervals such that the one of the audio signals is transmitted in a time interval in the second form while the other is being transmitted in a time interval of corresponding length in the first form and vice-versa, parts of the one and the other audio signals not transmitted in the first form thereby being transmitted in the second form so that the two audio signals are transmitted in their entireties in said frequency band but are transmitted in part in the first form and in part in the second form, both of the two audio signals being available in the transmitted signal for selection in their entireties from said first and second forms. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A secure audio signal transmission system comprising:
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first and second sources for at least two different audio signals; means for transmitting in a first form within a predetermined frequency band one and then the other of the audio signals in a sequence of time intervals such that parts but not all of each of the two audio signals are transmitted in the frequency band in the first form, said transmitting means including means for transmitting within said frequency band, in a second form distinguishable from said first form, one and then the other of the audio signals in said sequence of time intervals such that the one of the audio signals is transmitted in a time interval in the second form while the other is being transmitted in a time interval of corresponding length in the first form and vice-versa, parts of the one and the other audio signals not transmitted in the first form thereby being transmitted in the second form so that the two audio signals are transmitted in their entireties in said frequency band but are transmitted in part in the first form and in part in the second form, both of the two audio signals being available in the transmitted signal from said transmitting means for selection in their entireties from said first and second forms. - View Dependent Claims (10, 11, 12)
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13. A method for transmitting and receiving information in a communications medium comprising the steps of:
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providing an audio signal and a plurality of information signals, the information signals each being limited in frequency to a predetermined audio frequency range; generating a plurality of distinctive carrier signals within a predetermined frequency band allocated for transmission of audio in a single channel within said medium; modulating a first one of the plurality of carrier signals with at least one of the plurality of information signals; modulating a second of the plurality of carrier signals with at least another of the plurality of information signals; combining the audio program signal and the modulated first and second carrier signals to form a composite baseband audio signal; transmitting the composite baseband audio signal at a carrier frequency within the audio frequency band allocated to said channel; detecting the composite baseband audio signal in the transmitted signal; and selecting any of the audio signal and the plurality of information signals from the detected composite baseband audio signal as a useable output signal. - View Dependent Claims (14, 15, 16)
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17. Apparatus for transmitting and receiving information in a communications system comprising:
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means for providing an audio signal and a plurality of information signals, the information signals each being limited in frequency to a predetermined audio frequency range; means for generating a plurality of distinctive carrier signals within a predetermined frequency band allocated for transmission of audio in a single channel within the communications system; means for modulating a first and a second of the plurality of carrier signals with at least one and another, respectively, of the plurality of information signals; means for combining the audio signal and the modulated first and second carrier signals to form a composite baseband audio signal; means for transmitting the composite baseband audio signal at a carrier frequency within the audio frequency bands allocated to said channel; and means remote from the transmitting means for detecting the composite baseband audio signal in the transmitted signal and selecting any of the audio signal and the plurality of information signals from the detected composite baseband audio signal as a useable output signal. - View Dependent Claims (18, 19, 20)
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Specification