Adaptive DC-compensation
AssigneePC-Tel, Inc.
InventorKhashayar Mirfakhraei
Life of this patent
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Abstract
A receiver compensates for DC or baseline wander using a multi-tap filter to predict the shift in each sample of a received signal. The multi-tap filter is adaptive through coefficients updated during operation of the receiver. For each prediction, filter coefficients of the multi-tap filter change according to the error in the preceding prediction so that the changed coefficients would have provided a better prediction of the baseline shift for the preceding sample. The changed filter coefficients generally provide better future predictions.
Claims15
A method for compensating for baseline wander in a signal, comprising:
- sampling the signal to generate a series of samples;
- predicting a predicted shift for a selected sample from the series of samples, wherein predicting the predicted shift comprises performing a filter operation on values derived from the samples, wherein the filter operation includes a multi-tap adaptive filter operation and a fixed filter operation for compensation of the baseline wander, and wherein the fixed filter operation is an integrator generating the predicted shift based on a previous predicted shift;
- adding the predicted shift to the selected sample to generate a corrected sample;
- determining a difference between the corrected sample and a value permitted according to a signal protocol;
- and
- adjusting coefficients of the multi-tap filter operation according to the difference.
A communication device comprising:
- a converter that converts a received signal to a series of samples;
- and
- an adaptive DC compensation unit connected to operate on the series of samples and to adapt according to values of the samples, the DC compensation unit comprising:
- shift prediction unit that generates of a series of predicted shifts;
- a first adder that receives samples from the converter as a first addend and predicted shifts from the shift prediction unit as a second addend;
- and
- a slicer that processes sums from the first adder to identify symbol values according to a signal protocol, wherein
- the shift prediction unit comprises:
- a multi-tap filter having coefficients that change according to differences between the sums from the first adder and permitted amplitudes of a transmitted signal in compliance with the signal protocol;
- and
- an integrator that receives an integrand from the multi-tap filter, the integrator having fixed coefficients and generating the series of predicted shifts based on previous predicted shifts, the integrand and the fixed coefficients.
Dependencies are inferred from the claim text.