Method and apparatus for detecting reception of a tone signal
US5572588A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 5, 1994 |
| Grant date | Nov 5, 1996 |
| Priority date | — |
| Expiry date | Jul 5, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/46
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Tone detection may be accomplished by receiving an in-phase signal component 203 and a quadrature signal component 204. These components are then sampled to produce a plurality of sampled in-phase signal components 207 and a plurality of sampled quadrature signal components 208. The sampled in-phase signal components 207, or the sampled quadrature signal components 208, are then shifted by a pre-determined phase angle to produce a plurality of shifted components. Having shifted these signals, the shifted signals, or at least a set of them, are compared with the opposite non-shifted sampled signals, or a set thereof. When each of the shifted signal components substantially match the opposite non-shifted signal components, a tone signal is being received.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.