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. 24, 1998
Filed:
Sep. 25, 1995
Anthony H Richards, Cambridge, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
An FSK zero IF receiver has means (DEM) for producing representations of demodulated modulating signals as a series of narrow pulses having a repetition rate greater than the symbol rate of the modulating signals and an adjustable symbol slice demodulator (54 to 66) for determining the data. The demodulator has means for adjusting a symbol slice threshold value in dependence of the pulse like representations of the deviation frequencies which may be different as a result of drifting between the local oscillator and nominal transmitter carrier frequencies (f.sub.L and f.sub.C). The means for adjusting the symbol slice threshold comprises means for measuring the peak excursions of the instantaneous representations of the frequency, the difference between the peak excursions being proportional to the transmitted deviations, means for calculating the mean deviation of the peak excursions, which mean deviation is proportional to the offset between the transmitted center frequency and the local oscillator frequency, and means for setting the symbol slice level to the mean deviation in the case of a 2 level signal or to a plurality of symbol slice levels in the case of a M-ary signal.