Method and apparatus for detecting control signals
US5442696A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 31, 1991 |
| Grant date | Aug 15, 1995 |
| Priority date | — |
| Expiry date | Dec 31, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/4575
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The present invention provides a method and apparatus for detecting control signal information for an element of a communication system. The control signal information is included in one or more segments of a signal communicated over a communication system channel. The invention provides for the application of a plurality of tapers to a segment of a communicated signal; the transformation of a tapered segment; the determination of a similarity score based on a transform of a tapered segment and a model of a control signal; the identification of control signal information based on a similarity score; and the creation of an indicator signal representative of the identified control signal information to the communication system element. The control signal information may comprise a dual-tone multi-frequency signal. The tapers may comprise a discrete prolate spheroidal sequence. A similarity score may be determined based on a ratio of energy distributions. The numerator of the ratio may comprise an energy distribution based on a control signal model, and the denominator of the ratio may comprise an energy distribution based on a difference between a transformed tapered segment and the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.