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. 27, 1990
Filed:
Sep. 16, 1988
David C Nicholas, Cedar Rapids, IA (US);
Rockwell International Corporation, El Segundo, CA (US);
Abstract
A method is provided for searching a wide, high-noise frequency band for a narrow, phase-modulated signal to determine the approximate carrier frequency of a data signal. The method comprises the steps of sampling a received signal at a rate sufficiently high to cover the search bandwidth, performing an efficient Fourier transform on the sampled signal to obtain a discrete point power spectral density, filtering each frequency component of the power spectral density with averaging filters, analyzing the filtered components to find the area of greatest power concentration, and computing the center frequency of the area of greatest power concentration. The method determines the approximate carrier frequency of a data signal quickly and efficiently for use in starting or detecting loss of lock in a frequency-locked demodulator.