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:
Mar. 05, 2002
Filed:
Feb. 01, 1999
Hideki Matsuura, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
In a quadrature amplitude modulation signal demodulation circuit including first and second delay circuits for receiving an I-axis component and an Q-axis component of a baseband signal, a tap coefficient calculating circuit for calculating first tap coefficients in accordance with the delayed I-axis component and second tap coefficients in accordance with the delayed Q-axis component, an interference detection circuit for detecting a center of an interference signal included in the baseband signal, a control circuit for controlling delay time periods of the first and second delay circuits in accordance with an output signal of the interference detection circuit, first and second equalizers for equalizers the I-axis component and the Q-axis component in accordance with the first and second tap coefficients, and an adder for adding the output signals the first and second transversal equalizers, the interference detection circuit is constructed by a plurality of absolute value adders, each for adding an absolute value of one of the first tap coefficients and one of the second tap coefficients having the same timing, and a comparator for comparing output values of the absolute value adders with each other.