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US 6,661,858 B1Granted
DC restoration circuit for a radio receiver
OwnerAndré Beaudininventor
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OwnerAndré Beaudininventor
Estimating the term…
This invention relates to communications (radio) receiver circuitry and, in particular, to circuitry for eliminating a varying DC distortion component of a demodulated received information signal such as comprising data packets. This invention uses an adaptive filter, and a corresponding adaptive (equalization) feedback signal, to remove a slow varying (exponential) DC component of the signal. In the decoding circuitry of a receiver the adaptive filter (e.g. an LMS filter) compares the outputs of an integrate and dump component to adapted outputs of a decision component in order to produce an error signal which inherently corresponds to the varying DC component of the symbol stream. This equalizing adaptive error signal is fed back and subtracted from the symbol integral stream to remove the varying DC component therefrom and thereby restore the information packet to a level DC bias condition.
DC restoration circuitry for a communications receiver for removing a varying DC component of an information signal comprising a stream of symbols, said receiver comprising symbol recovery circuitry including a decision component for evaluating symbol acquisition values and producing a decision for each evaluated symbol acquisition value, said DC restoration circuitry comprising an adaptive filter configured for producing estimates of input symbol acquisition values which are correlated to the decisions made by said decision component for previously input symbol acquisition values and for subtracting said estimates from said input symbol acquisition values to produce a feedback error signal used to restore the DC level of said stream of symbols, wherein said estimates are not correlated to said DC component and said error signal represents said varying DC component.
Dependencies are inferred from the claim text.