Pulse or digital communications – Receivers – Interference or noise reduction
Patent
1997-06-10
1999-09-14
Chan, Jason
Pulse or digital communications
Receivers
Interference or noise reduction
375232, 704233, 381 941, H03D 104, H03D 106, H03K 501, H03K 604
Patent
active
059533803
ABSTRACT:
In accordance with the present invention, for noise cancellation, a reference noise signal is input to signal-to-noise (SN) power ratio estimating circuitry via a reference signal input terminal. The SN power ratio estimating circuitry causes its adaptive filter for producing a pseudonoise signal from the reference noise signal to operate. The circuitry detects error signal power and pseudonoise signal power out of the pseudonoise signal and other signals, and then outputs an estimate of an SN power ratio based on the detected power. A first delay circuit is connected to the output terminal of the above circuitry. A comparator compares an estimate of an input to and an estimate of an output from the first delay circuit, and produces greater one of the two estimates as an expanded estimate. A step size output circuit controls, based on the expanded estimate, the step size of a second adaptive filter connected to the reference signal input terminal via a second delay circuit. A subtracter subtracts a pseudonoise signal output from the second adaptive filter from a received signal sequentially delayed by a third and a fourth delay circuit, thereby cancelling a background noise signal component contained in the received signal.
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Chan Jason
Corrielus Jean B
NEC Corporation
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