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:
Jul. 02, 1996
Filed:
Oct. 26, 1994
Arthur E Fleek, Cary, NC (US);
William O Camp, Jr, Chapel Hill, NC (US);
Gary M Warchocki, Owego, NY (US);
Michael J Bracco, Raleigh, NC (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A carrier sensing circuit coupled to a receiving amplifier, measures the frequency of a phase shift modulated carrier signal by counting a predetermined number of the pulses for a measured interval whose duration is determined by counting a first clock count value. A demodulator coupled to the amplifier, detects when the spacing between the edges of the square wave pulses changes in response to the phase shift modulation. The demodulator measures first intervals between consecutive rising edges of the received signal, by counting clock pulses for a second selected interval whose duration is determined by a second selected count value. The demodulator further measures second intervals between consecutive falling edges of the received signal by counting clock pulses for a third selected interval whose duration is determined by a third selected count value. A compensating circuit coupled to the carrier sensing circuit and to the demodulator, compensates for frequency drift in the carrier signal or in the local oscillator by adjusting the second selected count value and the third selected count value, using the first clock count value.