Spread spectrum demodulator
US4039749A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 8, 1975 |
| Grant date | Aug 2, 1977 |
| Priority date | — |
| Expiry date | Sep 8, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B7/216
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The present invention is directed to a demodulator for demodulating a wideband spread spectrum four-phase PSK (phase shift keyed) modulated carrier signal wherein the phase modulation was in response to an encoded data signal and wherein the encoding of the data signal and spreading of the spectrum was accomplished by the mixing of the data signal with a pseudo-random pulse sequence (PN-sequence). The demodulator is comprised in part of a generator means for providing a pseudo-random pulse sequence corresponding to the sequence used to encode the data signal; and an encoding means for converting the provided PN-sequence into a four-phase PN sequence. A correlation means correlates the generated four-phase PN sequence against the received four-phase PSK modulated carrier signal to provide a two-phase collapsed spectrum signal. A switching means interposed between correlation means and the generator means switches two of the four phases of the four phase PN-sequence signal applied to the correlation means until proper phasing is achieved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.