The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 14, 1999
Filed:
Jun. 10, 1997
Shigeji Ikeda, Tokyo, JP;
NEC Corporation, Tokyo, JP;
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.