PSK demodulator with baseband correction for phase or frequency errors

Abstract

Abstract The device for coherent demodulation comprises a demodulation circuit (CD) and a carrier-recovery circuit (CRP2) produced entirely in digital form. Two carrier waves for quadrature demodulation which are produced by means of the local oscillator (21) are mixed with the signal from demodulation carriers modulated by symbols (SI) in order to produce analog signals (X<*>, Y<*>). The analog signals are digitised by sampling at the symbol reception frequency (1/T) into incoming digital signals (X@, Y@). <??>The digital phase-shifter (24) shifts the incoming signals (X@, Y@) by a demodulation phase (dn) set up by the phase-loop digital processing circuit (26) on the basis of pulses of an error signal delivered by the comparison circuit (25) receiving outgoing digital signals (X@, Y@) output by the said phase-shifter (24). <??>Compensation of the phase and frequency differences between the demodulation and modulation carrier waves is performed a posteriori in digital form by phase-shifting the incoming signals (X@, Y@). <IMAGE>

Inventors

• 👤 Patrick Vandamme
• 👤 Joelle Kervarec
• 👤 Alain Leclert

Bibliographic Details