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. 21, 1984
Filed:
Mar. 29, 1982
Richard R Kurth, Sudbury, MA (US);
Sperry Corporation, New York, NY (US);
Abstract
An apparatus and method for measuring the average or carrier frequency of a frequency shift keyed (FSK) signal which consists of sinusoidal tones that alternate regularly in frequency at a known rate between two unknown frequencies separated by a known frequency shift. The incoming signal is multiplied by two delayed versions of itself to yield to product signals. The delay employed in the first version is nominally equal to the FSK shift rate and the second delay differs from the first by an incremental amount. The two product signals are passed through substantially identical bandpass filters centered at the shift frequency and having a bandwidth approximately equal to the shift rate, and the phase angles of the filtered signals are differentially compared and averaged to produce a signal proportional to the average frequency of the FSK signal.