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. 08, 2003
Filed:
Mar. 15, 2001
Applicant:
Inventors:
Youhong Lu, Vernon Hills, IL (US);
Wenshun Tian, Rolling Meadows, IL (US);
Assignee:
3Com Corporation, Santa Clara, CA (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04M 1/00 ; H04M 3/00 ;
U.S. Cl.
CPC ...
H04M 1/00 ; H04M 3/00 ;
Abstract
A system and method for DTMF tone detection receives an input signal. The input signal includes a DTMF tone. The DTMF tone has a first frequency and a second frequency. An initial first frequency and an initial second frequency of said DTMF tone are selected by calculating a plurality of cost functions. The initial first frequency is confirmed to be the first frequency and the initial second frequency is confirmed to be the second frequency using re-computed values of the plurality of cost functions.