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:
Nov. 02, 2004
Filed:
Dec. 05, 2000
Applicant:
Inventor:
Philip Ching, Ottawa, CA;
Assignee:
Zarlink Semiconductor Inc., Ottawa, CA;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M 1/00 ; H04M 9/00 ; H04M 9/08 ;
U.S. Cl.
CPC ...
H04M 1/00 ; H04M 9/00 ; H04M 9/08 ;
Abstract
An apparatus for detecting a dual tone alert signal in a telephone system capable of at least off hook mode operation includes a processing channel for each tone. Each channel consists of a bandsplit filter for extracting the tone of interest and attenuating the other tone; a comparator for comparing the output of said bandsplit filter with a threshold value; and an adaptive threshold generator for generating said threshold value adapted to the amplitude of the output of said bandsplit filter to reject speech and music imitations. The apparatus offers improved talkdown and talkoff immunity.