System for detecting the presence of a digital signal carrier wave, and a receiver including such a system
US6175600A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1997 |
| Grant date | Jan 16, 2001 |
| Priority date | — |
| Expiry date | May 13, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/027
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The invention relates to a system for detecting the presence of a carrier wave in a digital signal that is available at a given frequency. The system delivers at least two baseband samples of the digital signal at each symbol time. The system comprises a timing estimator responsive to the baseband samples to deliver an error signal (.epsilon.) corresponding to the phase error between the clock frequency that is to be recovered and a local clock frequency, and a detector that generates a detection signal indicating that a carrier wave has been detected whenever a level representative of the variance of the error signal (.epsilon.) reaches a threshold value. The invention is particularly applicable to receivers of signals transmitted in DTMA mode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.