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:
Apr. 06, 1993
Filed:
Jun. 22, 1992
Iddo Carmon, Kfar-Sava, IL;
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A QAM modem receiver performs fine-timing on a baseband signal sampled at two complex points per symbol. Based on this information, the algebraic signs of the second derivative of the baseband signal are estimated. These signs, computed separately for the real and imaginary axes, are used to a make local decision regarding convexity/concavity of the baseband signal. By accumulating these local decisions over an appropriate time interval, a global decision is reached regarding the sampling point position relative to the baseband signal maxima/minima. Based on this global decision, a correction command is issued to the modem's analog front end to either advance or delay the timing.