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:
Feb. 03, 2004
Filed:
Sep. 29, 2000
Xiangzhou Joe Zhang, Richmond, CA (US);
Robin A. Bordow, Petaluma, CA (US);
Agilent Technologies, Inc., Palo Alto, CA (US);
Abstract
A first system includes a converter, complex signal generator, exponentiator, FFT module and processor to estimate carrier frequency of a high symbol rate quadrature amplutide modulated (QAM) signal relative to a target carrier frequency. The converter converts the applied QAM signal to an intermediate frequency (IF) signal and digitizes the IF signal at a predesignated sample rate. The complex signal generator extracts a real component of the digitized IF signal, provides an imaginary component of the digitized IF signal and then combines the real component and the imaginary component in a complex signal. The exponentiator, raises the complex signal to a predesignated power and the FFT module performs a Fast Fourier Transform (FFT), having a predetermined number of samples, on the complex signal as raised to the predesignated power. The processor, takes the magnitude of the resulting FFT, extracts the index of a sample within the resulting FFT having the greatest magnitude and estimates the carrier frequency of the applied QAM signal relative to a target carrier frequency based on the predesignated power, the extracted index and the predesignated sample rate. In a second system a quadrature downconverter replaces the complex signal generator.