Reduced-tap filter in a demodulator
AssigneeHewlett-Packard Company
InventorsMark Unkrich, William J. Hillery, V. Rao Sattiraju
Life of this patent
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Abstract
A demodulator with a filter having a reduced number of filter taps without a sacrifice in filter accuracy. The demodulator includes elements that generate a data stream that carries a component of an input signal in response to a data stream that carries samples of the input signal. The demodulator also includes elements that generate a sample clock for sampling the input signal such that the sample clock is preselected to cause the data stream that carries the component to carry alternating samples that are substantially equal to zero. The filter in the demodulator has a set of filter taps which are arranged to tap only the samples in the data stream that carries the component that are not substantially equal to zero.
Claims17
A demodulator, comprising:
- means for generating at least one data stream that carries a component of an input signal in response to a data stream that carries samples of an input signal;
- means for generating a sample clock for sampling the input signal and providing the data stream that carries samples of the input signal such that the sample clock is preselected to cause the data stream that carries the component to carry alternating samples that are substantially equal to zero;
- filter having a set of filter taps which are arranged to tap only the samples in the data stream that carries the component that are not substantially equal to zero.
A demodulator, comprising:
- analog-to-digital converter that generates an input signal in response to a sample clock;
- down conversion circuit that generates at least one data stream that carries a component of the input signal in response to the input signal;
- phase locked loop circuit that adjusts a frequency and a phase of the sample clock such that the data stream that carries the component carries alternating samples that are substantially equal to zero;
- filter having a set of filter taps which are arranged to tap only the samples in the data stream that carry the component that are not substantially equal to zero.
A method for reducing a number of filter taps in a filter of a demodulator, comprising the steps of:
- generating at least one data stream that carries a component of an input signal in response to a data stream that carries samples of the input signal;
- generating a sample clock for sampling the input signal and providing the data stream that carries samples of the input signal;
- adjusting the sample clock such that the sample clock causes the data stream that carries the component to carry alternating samples that are substantially equal to zero which enables the filter taps to be arranged to tap only the samples in the data stream that carries the component that are not substantially equal to zero.
Dependencies are inferred from the claim text.