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:
Oct. 16, 2001
Filed:
Mar. 03, 1999
Shahriar Rabii, Palo Alto, CA (US);
Level One Communications, Inc., Sacramento, CA (US);
Abstract
An FM demodulator circuit with reduced sensitivity to noise and performance nearly identical to theoretical predictions. The FM demodulator is a time sampled detector for binary shift key (BFSK) modulated signals. Its inputs are an in-phase and a quadrature outputs of a receiver, which have been oversampled by a predetermined factor with respect to the data rate. The demodulator circuit differentiates the in-phase and the quadrature input signal by computing the difference between the current signal value and the signal value delayed by one clock period. The differentiated values of the in-phase and the quadrature signals may be changed based on the sign of the quadrature and the in-phase signals respectively to produce modified values of the differentiated in-phase and quadrature signals. Processing of the modified differentiated in-phase and quadrature values to produce an output wherein the sensitivity to noise is reduced by discarding the smaller of the modified differentiated in-phase or quadrature signal. The resulting output signal is filtered and passed through a comparator to produce a digital waveform.