Spread spectrum demodulator
US4017798A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 8, 1975 |
| Grant date | Apr 12, 1977 |
| Priority date | — |
| Expiry date | Sep 8, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B7/216
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Demodulation of a wideband spread spectrum four-phase PSK (phase shift keyed) modulated carrier signal is accomplished by means of a correlator which phase shifts the modulated carrier signal as a function of a locally generated PN (pseudo-noise) sequence to provide a narrow band two-phase PSK modulated carrier signal. The two-phase modulated signal is fed to a matched filter wherein undesired signal components are removed so as to provide an IF (intermediate frequency) signal. A carrier recovery phaselock loop demodulates the two-phase modulated IF signal to provide a baseband signal. A timing recovery loop operates upon the baseband signal to provide timing signals for the locally generated PN sequence to synchronize the local PN sequence with the modulated carrier sequence. A bit timing loop and a sample and hold means operate upon the baseband signal to detect the modulating data to provide an output signal which is a function of the modulating data.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.