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. 24, 1981
Filed:
Dec. 10, 1979
Dominique N Godard, Le Rouret, FR;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and a device which, in a receiver forming part of a data transmission system using DSB-QC modulation, permit detecting the beginning of a pseudo-random sequence of symbols pertaining to a first set of two symbols when this sequence is preceded by a sequence of successive alternations between two symbols pertaining to a second set, with the first and second sets being such that the beginning of said pseudo-random sequence will initiate a reversal of the phase of the components of the frequency spectrum of said sequence of alternations. In accordance with the method of the present invention, the received signal is demodulated, the DC component of the demodulated signal is determined, and the energy of that DC component is measured. The time at which said energy drops below its average value is indicative of the beginning of the pseudo-random sequence. In accordance with one aspect of the invention, the DC component of the demodulated signal is determined by passing the signal through a lowpass filter.