Decimation filter
AssigneeSigma Tel, Inc.
InventorDarrell Tinker
Life of this patent
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Abstract
A system and method for decimating a digital signal is disclosed. The system includes an input to receive digital data, a control input to receive a desired decimation rate, and an integrator stage responsive to the input. The system also includes a variable rate down sampling module responsive to the integrator stage and a differentiator stage responsive to the variable rate down sampling module. The down sampling module has a decimation rate that is dynamically adjustable based on the desired decimation rate.
Claims41
A digital decimation filter, comprising:
- an input to receive a digital data stream;
- a control input to receive a desired decimation rate;
- an integrator stage responsive to the input;
- a variable rate down sampling module responsive to the integrator stage, wherein the down sampling module has an adjustable decimation rate, and wherein the adjustable decimation rate is dynamically adjusted based on the desired decimation rate;
- and
- a differentiator stage responsive to the variable rate down sampling module.
The digital decimation filter of claim I1, wherein the decimation rate is adjusted by changing a second time interval between the second of the plurality of samples and a third of the plurality of samples.
A down sampling module, comprising:
- an accumulator of a cascade integrator comb (CIC) filter to receive and store a decimation interval from a control module, wherein the decimation interval includes an integer portion and a fractional portion, and wherein the decimation interval is based on a dynamically determined decimation rate;
- and
- an interpolator responsive to the accumulator to receive a digital sample and to provide an output based on an interpolation of the digital sample.
A method comprising:
- receiving a sample rate source input;
- dynamically determining a first decimation rate adjustment control signal based on the sample rate source input at a first time;
- and
- providing the first decimation rate adjustment control signal to a variable rate decimation filter;
- and
- wherein the variable rate decimation filter includes an input to receive a digital data stream, a control input to receive a desired decimation rate, an integrator stage responsive to the input, a variable rate down sampling module responsive to the integrator stage, and a differentiator stage responsive to the down sampling module, wherein the down sampling module has an adjustable decimation rate that is dynamically adjusted based on the desired decimation rate.
A method, comprising:
- receiving at a cascade integrator comb (CIC) filter a first input digital sample of a digital input signal at a first time;
- storing a decimation interval in an accumulator including an integer portion;
- upon receiving the first digital input sample, iteratively decrementing the integer portion of the accumulator at a clock rate;
- providing a digital output sample at an output of a decimation module at a second time, the second time after the integer portion of the accumulator has been decremented to a threshold amount, the output sample based on the input sample;
- changing the decimation interval by a decimation interval adjustment amount to produce a changed decimation interval;
- and
- storing the changed decimation interval in the accumulator.
A system comprising:
- a decimation module having an adjustable decimation rate;
- a filter module responsive to the decimation module;
- a digital phase lock loop to control a decimation rate of the decimation module;
- and
- wherein the decimation module is a cascade integrator comb decimation module.
Dependencies are inferred from the claim text.