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. 22, 1977
Filed:
Jun. 23, 1975
Applicant:
Inventors:
Randell Leland James, Austin, TX (US);
James Thomas Padden, Austin, TX (US);
Assignee:
International Business Machines Corporation, Armonk, NY (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ;
Abstract
Disclosed is a method and apparatus for detecting the presence of signals, particularly touch-tone signals, of characteristic complex waveforms by comparing unknown signals with pre-specified digital formats or 'masks' representative of such waveforms. The apparatus includes digital circuitry defining the masks and digital circuitry for counting the number of times during a prescribed time period there is a correlation between the digital format of the unknown signals and the masks.