Apparatus and method for providing digital audio on the sound carrier of a standard television signal
First Claim
1. A method for providing a digital audio signal in a sound carrier portion of an approximately 6 MHz radio frequency channel of a television signal, said sound carrier portion located outside of an approximately 4.25 mHz band width video portion of said radio frequency channel, said method comprising the steps of:
- generating a video signal having an approximately 4.25 MHz band width for inclusion in said channel,generating a digitized audio signal associated with the video signal;
modulating the digitized audio signal using multi-phase modulation on a sound carrier for inclusion in said channel;
summing the modulated sound carrier and the video signal in an approximately 6 MHz band to produce a composite output signal, said sound carrier being located outside of the video band in said 6 MHz band; and
transmitting the sum in said 6 MHz radio frequency channel for receipt by a video appliance.
2 Assignments
0 Petitions
Accused Products
Abstract
A television transmission system replaces the standard FM audio portion of a television signal with digital audio. Three digital audio channels are time division multiplexed on the sound carrier, using combined multi-phase and AM modulation. The audio signals are digitized using adaptive delta modulation techniques. Video vertical and horizontal framing, as well as the audio carrier phase reference, audio data bit time and frame reference, and various control data is carried using AM modulation. The digital audio information is carried using multi-phase modulation. The composite data stream may be serially encrypted to provide security and prevent unauthorized reproduction of the video and/or audio portions of the television signal.
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Citations
47 Claims
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1. A method for providing a digital audio signal in a sound carrier portion of an approximately 6 MHz radio frequency channel of a television signal, said sound carrier portion located outside of an approximately 4.25 mHz band width video portion of said radio frequency channel, said method comprising the steps of:
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generating a video signal having an approximately 4.25 MHz band width for inclusion in said channel, generating a digitized audio signal associated with the video signal; modulating the digitized audio signal using multi-phase modulation on a sound carrier for inclusion in said channel; summing the modulated sound carrier and the video signal in an approximately 6 MHz band to produce a composite output signal, said sound carrier being located outside of the video band in said 6 MHz band; and transmitting the sum in said 6 MHz radio frequency channel for receipt by a video appliance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. Headend apparatus for providing a digital audio signal in a sound carrier portion of an approximately 6 MHz channel of a transmitted television signal, said sound carrier portion located outside of an approximately 4.25 MHz band width video portion of said radio frequency channel, said apparatus comprising:
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means for generating a video signal having an approximately 4.25 MHz band width for inclusion in said channel; means for generating a high fidelity, digital audio signal; means coupled to receive a digital audio signal from the digital audio generating means, for modulating the digital audio signal on a sound carrier for inclusion in said channel adjacent to the video band without the modulated sound carrier being impaired by said video signal; means coupled to receive the modulated sound carrier for converting the modulated sound carrier to an intermediate frequency; and means coupled to receive the converted modulated sound carrier signal from said converting means and to receive the video signal from a video signal path for summing the converted modulated sound carrier signal with the video signal, thereby producing a composite output signal and transmitting the sum in said channel to a video appliance, said sound carrier being located outside of the video band within said channel. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A converter for providing reproduction of digital television in a sound carrier portion of an approximately 6 MHz channel of a television signal, the channel also including a video signal having an approximately 4.25 MHz band transmitted simultaneously with said digital television sound, said sound carrier portion located outside of the video signal band within said channel of a television signal, said converter comprising:
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a tuner for receiving said channel of the television signal; detector means coupled to the output of said tuner for detecting a digital audio signal from a modulated sound carrier having a center frequency within said channel outside of said video band without impairment by the simultaneously transmitted video signal; demodulator means coupled to receive the detected digital audio signal for demodulating the detected digital audio signal to produce digital audio data; decoding means for converting the demodulated digital audio data to an analog audio signal; and means for outputting said analog audio signal to a television set. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47)
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Specification