Phase shift keying and phase modulation transmission system
US4682118A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 16, 1985 |
| Grant date | Jul 21, 1987 |
| Priority date | — |
| Expiry date | Sep 16, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D3/241
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A PSK and phase modulation transmission system has a modulator and a demodulator. The modulator has a carrier frequency generator (21) coupled to a voltage controlled phase shifter (22). The modulation of the signal in the shifter (22) is controlled by modulation voltage generator (23). A transmitter (24) receives the output from the shifter (22) and transmits the modulated signal. The demodulator (30) includes a receiver section (31) for receiving the signal transmitted by the transmitter (24). The receiver (31) is coupled to a modified phase locked loop comprising a phase detector (32), a low pass filter (33), a sample and a hold circuit (34) and a voltage controlled oscillator (35). A lock control circuit (36) receives either the output from the receiver (31) or the output from the filter (33) to produce a lock in pulse from changes in the received signal or changes in the demodulated signal at the filter (33) for controlling the sample and hold circuit (34).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.