Four phase PSK demodulator
US4757272A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 1, 1986 |
| Grant date | Jul 12, 1988 |
| Priority date | — |
| Expiry date | Jul 1, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2277
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A demodulator for regenerating and demodulating a carrier signal from a four-phase PSK received signal having a data symbol preamble and a fixed phase (one of four phases) of a particular time width using a synchronous detection type demodulating system (remodulation type demodulating system). The demodulator includes an orthogonal demodulating circuit and a remodulating circuit for regenerating a carrier signal which is the data signal during a preamble transmission period from a received modulated signal. The remodulating circuit includes a demodulator having an AFC circuit for detecting a frequency change using a narrow band filter, means for suppressing frequency changes of the four-phase PSK modulated signal received and means for rendering constant the frequency of the regenerated carrier signal passing through the narrow band filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.