Multiple signal transmission method and system, particularly for television

A method for transmitting television audio and video program signals comprising the steps of:

• providing at least two different audio signals and at least one television video program signal, at least one of the audio signals being a television audio program signal associated with the television video program signal;
• transmitting the video program signal in a first frequency band;
• transmitting in a first form within a second 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 second frequency band in the first form;
• transmitting within said second 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 the second 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.

A method for operating a subscription television system comprising the steps of:

• transmiting a scrambled television video signal within a first frequency band together with both an unscrambled audio signal and a plurality of scrambled audio signals within a second frequency band, the first and second frequency bands being within an overall frequency band allocated to a single television channel;
• receiving the transmitted first and second frequency bands containing the scrambled video signal, the unscrambled audio signal and the plurality of scrambled audio signals;
• selectively displaying a scrambled or an unscrambled television video signal in response to the received scrambled television video signal in the first frequency band;
• selectively producing audio with the displayed scrambled television video signal in response to the received unscrambled audio signal in the second frequency band and producing audio with the displayed unscrambled television video signal in response to a selected one of the plurality of scrambled audio signals in the received second frequency band.

Apparatus for scrambling a plurality of input signals for secure transmission thereof comprising:

• means for generating an in-phase and a quadrature component of at least one carrier signal;
• means for modulating the in-phase component of said at least one carrier signal in response to one and then another of the plurality of input signals in a sequence of time intervals such that parts but not all of said one another of the input signals are carried by said in-phase component;
• means for modulating the quadrature component of said at least one carrier signal in response to said one and then said another of said plurality of input signals in said sequence of time intervals such that parts but not all of said one and another input signals are carried by said quadrature component and such that said in-phase and quadrature components together carry said two input signals in their entireties;
• and,
• means for combining said modulated in-phase and quadrature components for transmission.

A television audio and video program signal transmission system comprising:

• first and second sources for at least two different audio signals and a third source for at least one television video program signal, at least one of the audio signals being a television audio program signal associated with the television video program signal;
• first transmitting means for transmitting the video program signal in a first frequency band;
• second transmitting means for transmitting in a first form within a second 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 second frequency band in the first form, said second transmitting means including means for transmitting within said second 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 the second 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 second transmitting means for selection in their entireties from said first and second forms.

A subscription television system comprising:

• means for transmitting a scrambled television video signal within a first frequency band together with both an unscrambled audio signal and a plurality of scrambled audio signals within a second frequency band, the first and second frequency bands being within an overall frequency band allocated to a single television channel;
• means for receiving the transmitted first and second frequency bands containing the scrambled video signal, the unscrambled audio signal and the plurality of scrambled audio signals;
• means for selectively displaying a scrambled or an unscrambled television video signal in response to the received scrambled television video signal in the first frequency band;
• and,
• means for selectively producing audio with the displayed scrambled television video signal in response to the received unscrambled audio signal in the second frequency band and producing audio with the displayed unscrambled television video signal in response to a selected one of the plurality of scrambled audio signals in the received second frequency band.

A method for transmitting and receiving information in a television system comprising the steps of:

• providing a television video program signal, a television audio program 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 to a single television channel;
• 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 video program signal and the composite baseband audio signal at carrier frequencies within respective video and audio frequency bands allocated to a single television channel for transmission of video and audio;
• detecting the composite baseband audio signal in the transmitted signal;
• and
• selecting any of the audio program signal and the plurality of information signals from the detected composite baseband audio signal as a useable output signal.

Apparatus for transmitting and receiving information in a television system comprising:

• means for providing a television video program signal, a television audio program 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 to a single television channel;
• 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 program signal and the modulated first and second carrier signals to form a composite baseband audio signal;
• means for transmitting the video program signal and the composite baseband audio signal at carrier frequencies within respective video and audio frequency bands allocated to a single televison channel for transmission of video and audio;
• and
• means remote from the transmitting means for detecting the composite baseband audio signal in the transmitted signal and selecting any of the audio program signal and the plurality of information signals from the detected composite baseband audio signal as a useable output signal.