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:
Mar. 04, 2014
Filed:
Feb. 24, 2011
David C. Smith, Columbia, MD (US);
David C. Smith, Columbia, MD (US);
Abstract
A method of demodulating an AIS signal by receiving the signal, sampling the signal, estimating the carrier frequency, estimating the complex conjugate of the carrier frequency contribution to each sample, multiplying each sample by the complex conjugate and calling the results a base-banded sampled signal (BBSS), correlating the BBSS with known preambles, identifying a maximum magnitude of the BBSS/preamble correlation and its location and the associated preamble, computing a complex inner product of the preamble with a segment of the BBSS, estimating the carrier phase as an argument function of the eighth step result, estimating a complex conjugate of the carrier phase contribution to the BBSS, multiplying each fifth step result starting at the location of the maximum magnitude of the BBSS/preamble correlation by the tenth step result, and demodulating the results starting at that location.