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.

Date of Patent:
Aug. 10, 1999

Filed:

Nov. 19, 1996
Applicant:
Inventors:

Nam-Sun Kim, Seoul, KR;

Young-Ky Kim, Seoul, KR;

Yoon-Seok Kang, Seongnam, KR;

Ho-Young Park, Seoul, KR;

Assignee:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ; H04M / ;
U.S. Cl.
CPC ...
379386 ; 379283 ; 379339 ;
Abstract

A dual tone multi-frequency detector includes a pulse code modulation expanding unit for converting pulse code modulation data into linear data. A correlating unit constructed from a plurality of correlators correlates the linear data with a plurality of predetermined reference signals to generate a plurality of power values of a frequency band corresponding to dual tone multi-frequency signals. A total power detecting unit detects a total power value of the linear data. A low frequency maximum power detecting unit detects a maximum low frequency power value from the power values of a low frequency band generated by the correlating unit. A high frequency maximum power detecting unit detects a maximum high frequency power value from the power values of a high frequency band generated by the correlating unit. A deciding unit decides whether or not the pulse code modulation data represents a dual tone multi-frequency signal in dependence upon the total power value, the maximum low frequency power value and the maximum high frequency power value.


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