LPC-based DTMF receiver for secondary signalling
US4853958A · kind A · utility
15Cited by
2References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 2, 1988 |
| Grant date | Aug 1, 1989 |
| Priority date | — |
| Expiry date | Jun 2, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/4575
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A dual tone multi-frequency (DTMF) receiver for use in detecting digitally transmitted signals in the telephone industry. The receiver derives linear predictive coefficients for the digital signals in the data frame. This information is used to compute frequency response magnitudes at the DTMF frequencies. A plurality of magnitude comparisons are then performed to verify the presence of true DTMF signals and concurrently the frequency of these signals is obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.