Multichannel digital signal generation method and apparatus
OwnerRon D. Katznelsoninventor
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Abstract
A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.
Claims10
A method of generating a broadband signal comprising up to 2N+1 RF signals having frequencies incrementally related to a center frequency by a fundamental frequency increment, each of the RF signals having an amplitude and phase characterized by a phasor value, said method comprising the steps of:
- generating a first and second baseband signal each comprising a linear combination of a zero frequency term and N sinusoids, each of the sinusoids having a frequency that is an integral multiple of the fundamental frequency;
- modulating in quadrature the first and second baseband signals on a third signal having a frequency equal to the center frequency;
- and
- determining a desired linear combination of sinusoids and zero frequency terms for the first and second baseband signals to achieve a desired phasor value for each of the RF signals.
Dependencies are inferred from the claim text.