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:
Jul. 09, 2002
Filed:
Jan. 14, 1999
Thomas J Endres, Perkasie, PA (US);
Samir N Hulyalkar, Plainsboro, NJ (US);
Christopher H Strolle, Glenside, PA (US);
Troy A Schaffer, Langhorne, PA (US);
Nxtwave Communications, Inc., Langhorne, PA (US);
Abstract
An adaptive equalizer for use in blind equalization systems to compensate for transmission channel distortion and noise in a digital communication system uses multiple quantization levels for implementation of the Constant Modulus Algorithm (CMA). Different quantization levels are used in different regions of the CMA error function for both passband and baseband equalizers. In one embodiment, a quantizer with a step rise having logarithmic scale is used to digitize the CMA error function. In particular, a quantizer with a step rise in which each level of the quantizer step rise is a power of 2 is used to digitize the CMA error function. In another embodiment, a quantizer with a step rise in which each level of the quantizer step rise is the sum of two or more logarithmic scales is used to digitize the CMA error function. In particular, a quantizer with a step rise wherein each level of the quantizer step rise is the sum of two or more numbers each of which is a power of 2 is used to digitize the CMA error function. The use of logarithmic scales, the sum of logarithmic scales, powers of 2, or the sum of powers of 2 for the quantizer step rise size to digitize the CMA error function make efficient use of shift and add operations to achieve multiplication in the adaptation process.