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. 18, 1989
Filed:
Sep. 16, 1988
Christian J Chuba, Scotch Plains, NJ (US);
Charles R Walden, Jr, Montclair, NJ (US);
Joseph J Grecco, Saddle Brook, NJ (US);
Jeffrey I Feinstein, Clifton, NJ (US);
Dialogic Corporation, Parsippany, NJ (US);
Abstract
Apparatus for detecting a single-frequency signal having a predetermined frequency in an analog signal includes means for converting the analog signal to a differentially encoded digital signal and detection means for detecting a single-frequency signal having the predetermined frequency from the differentially encoded digital signal. In a preferred embodiment, the detection means includes: means for detecting one cycle of the analog signal by detecting a signal maximum followed by detecting a signal minimum which is followed, in turn, by detecting another signal maximum; means for determining the length of the cycle, for determining whether the length is within predetermined bounds, and for keeping a count of such occurrences; and means for determining whether the count has reached a predetermined amount, whereby a single-frequency signal having the predetermined frequency has been detected.