Detection of tones while minimizing incorrect identification of other sounds as tones
US5765125A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 15, 1997 |
| Grant date | Jun 9, 1998 |
| Priority date | — |
| Expiry date | Jan 15, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/46
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A first validation circuit utilizes residual energy unaccounted for by a linear predictive coding model for a specified order of model as a criteria on which to make a validity determination of whether a valid tone or digit has been received. A second validation circuit operating in conjunction with the first validation circuit utilizes discrete Fourier transforms at the center and adjacent frequencies to energy peaks associated with tones. A ratio of the peak energy to the adjacent energies is utilized in combination with corresponding thresholds to make a validity determination. The combination of the first and second validation circuit provides a high level of confidence that a particular tone or digit has been detected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.