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:
Jan. 06, 1998
Filed:
Sep. 13, 1996
Carl H Alelyunas, Nevada City, CA (US);
Andrew L Norrell, Nevada City, CA (US);
Vladimir Parizhsky, Chicago, IL (US);
U.S. Robotics Access Corp., Lincolnshire, IL (US);
Abstract
A method in which correctable I/Q imbalance errors in a complex receiver can be detected and compensated for digitally without the use of special calibration signals. Differential D.C. offset errors are compensated by averaging the incoming I.sub.d and Q.sub.d digital signals and subtracting from them an expected value of differential D.C. offset, for example, computed from the long term average of the I and Q signals to create I' and Q' signals. Differential gain imbalance errors are corrected by calculating a root means square average of the I' and Q' digital signals and applies to them compensation coefficients K.sub.x and K.sub.y determined from either the RMS average or from a Stochastic Gradient Algorithm. The DSP compensates for the quadrature phase errors by calculating a compensation matrix which is independent of the frequency of the carrier and applies the compensation matrix to the I' and Q' digital signals. The compensation matrix for quadrature phase errors is completely independent of the frequency of the input carrier signal supplied to the complex receiver, and is not dependent on the use of a calibration signal. The compensation may be performed as a step in calibration of the complex receiver, or continuously.