Multifrequency detection
US5073941A · kind A · utility
13Cited by
0References
25Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Feb 1, 1988 |
| Grant date | Dec 17, 1991 |
| Priority date | — |
| Expiry date | Feb 1, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/4575
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The detection of DTMF tones is improved in a three-step process: first testing even-numbered samples; then testing odd-numbered samples, and finally testing for tone quality (time interval and frequency stability).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.