Apparatus and method for identifying speech and call-progression signals
US5319703A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 26, 1992 |
| Grant date | Jun 7, 1994 |
| Priority date | — |
| Expiry date | May 26, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/46
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method for real-time recognition of speech and call-progression tone energy includes the steps of digitizing an analog signal present on a signal line, correlating N neighboring portions of the digitized signal, performing FFT analysis on the digitized signal, identifying the three largest frequency-domain maxima, determining whether the two largest maxima are above a threshold frequency, and determining whether the ratio of the largest to the third largest maxima exceeds a predetermined value. According to the present invention, the steps of the method may be performed in real time using fixed-point hardware by approximating the correlation and FFT functions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.