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:
May. 18, 2004
Filed:
Jun. 01, 1999
Richard Bourdeau, St-Laurent, CA;
Harris Corporation, Melbourne, FL (US);
Abstract
A decision directed frequency detector and method for a quadrature amplitude modulated signal (QAM) demodulator. The demodulator interacts with a voltage controlled oscillator (VCO) that generates a carrier signal to demodulate the QAM signal into a baseband signal. The frequency detector determines the direction of rotation of the baseband signal by sampling the baseband signal relative to predetermined points in the phase plane. For example, if one sample has a negative phase offset with respect to a predetermined point and the next one has a positive phase offset, it detects that the rotation is clockwise, and vice-versa. A control signal is supplied to the VCO and the frequency of the carrier signal is adjusted to stop the rotation of the baseband signal.