Method and device for detecting a pseudo-random sequence of carrier phase changes of 0.degree. and 180.degree. in a data receiver
US4262360A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 10, 1979 |
| Grant date | Apr 14, 1981 |
| Priority date | — |
| Expiry date | Dec 10, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/046
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method and device which, in a receiver forming part of a data transmission system using DSB-QC modulation and wherein the transmitter generates a first sequence of successive carrier phase changes of 180.degree. taking place at the signaling rate 1/T followed by a second sequence of pseudo-random carrier phase changes of 0.degree. and 180.degree., with the first of these being a 0.degree. phase change, permit detecting the beginning of said second sequence. The received signal is filtered to extract therefrom its components at frequencies f.sub.1 and f.sub.2 defined as EQU f.sub.1 =f.sub.c -1/2T f.sub.2 =f.sub.c +1/2T where f.sub.c is the carrier frequency. The components at frequencies f.sub.1 and f.sub.2 are combined to generate a signal S of frequency 1/T. The beginning of said second sequence is determined by detecting the instant at which the energy of signal S drops below its average value. According to another aspect of the invention, the beginning of said second sequence is determined by detecting the instant at which the amplitude of the in-phase component, sampled at the signaling rate, of signal S decreases significantly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.