Adaptive efficient single/dual tone decoder apparatus and method for identifying call-progression signals
US5321745A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 27, 1992 |
| Grant date | Jun 14, 1994 |
| Priority date | — |
| Expiry date | Aug 27, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/46
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A process for determining the presence of either speech or one of a plurality of expected single-frequency signals on a line includes the steps of measuring the total signal energy on the line; measuring the signal energy present in each one of a plurality of selected separate frequency bands and identifying the two frequency bands having the highest signal energies; determining whether the highest signal energy exceeds a first selected threshold value; determining whether the highest signal energy exceeds the second highest signal energy by greater than a second selected threshold value; determining the amount of out-of-band signal energy; and determining whether the highest signal energy exceeds the out-of-band signal energy by greater than a third selected threshold value. A process for determining the presence of two of a plurality of expected a single-frequency signals on a line includes the steps of measuring the total signal energy on the line; measuring the signal energy present in each one of a plurality of selected separate frequency bands and identifying the three frequency bands having the highest signal energies; determining whether the two highest signal energies exce…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.