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. 27, 1996
Filed:
Feb. 28, 1994
Claude Cesaro, Le Cannet, FR;
Gerard Richter, Saint-Jeannet, FR;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method for detecting the presence of single tone and dual tone signals compares a ratio r which equals the square of the maximum value of the received signal (A max) during a sampling period divided by a measure E of the energy to three different thresholds. If r is less than the first threshold (3) a single tone is indicated. If it is greater than the first but less than the second (5.2) a dual tone is indicated. When a single tone is indicated the received signal is subjected to a second order autoregressive process to determine the frequency of the single tone. If a dual tone is indicated the received signal is subjected to a fourth order autoregressive process to determine the frequencies of the dual tones.