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. 23, 1993
Filed:
Sep. 06, 1991
Applicant:
Inventor:
Masanobu Arai, Tokyo, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H03K / ; H03K / ;
U.S. Cl.
CPC ...
328138 ; 328140 ; 307231 ;
Abstract
A tone signal detecting circuit includes a sampling circuit, a storage circuit, and a comparing circuit. The sampling circuit samples a tone signal at a sampling rate N times (N is a natural number) higher than a frequency f of the one signal. The storage circuit stores M (M is a natural number) latest values of time series data from the sampling circuit. The comparing circuit compares a plurality of polarity patterns expected on the basis of a tone signal with polarity patterns stored in the storage circuit and outputting coincidence outputs.