Apparatus for detecting the presence or the absence of a digitally modulated carrier, a corresponding receiver, and a corresponding method
US6081559A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 1995 |
| Grant date | Jun 27, 2000 |
| Priority date | — |
| Expiry date | Nov 30, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/206
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The invention relates to apparatus for detecting the presence or the absence of a signal carrier wave received by a receiver. The carrier wave is modulated by a digital signal at a symbol clock frequency. According to the invention, the apparatus includes: PA1 a non-linear circuit receiving the received signal or the received signal after it has been frequency transposed, the non-linear circuit supplying in particular a signal whose frequency corresponds to the symbol clock frequency; PA1 a narrow-band filter centered on the symbol clock frequency and supplying a filtered signal; PA1 detection means for detecting the filtered signal and for supplying a detection signal; and PA1 comparator means for comparing the detection signal with a reference value, the output signal from the comparator means constituting a signal indicating the presence or the absence of the carrier wave. The invention is particularly applicable to a receiver including automatic gain control apparatus placed upstream, and the indicator signal may optionally be applied to automatic frequency control apparatus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.