Patent ID: 6028888
Filing Date: 2000-02-22
Classification: H04B,H04L

Abstract:
A single-channel coherent demodulation device for regenerating, from a received signal, an input signal of single-channel Nth order complex spreading modulation device, said single-channel complex spreading modulation device applying to said input signal complex spreading followed by quadrature modulation to obtain a signal to be transmitted, said input signal having a bit rate D, said signal to be transmitted and said received signal each having a bit rate N*D, which device includes:quadrature demodulation means generating a demodulated signal at bit rate N*D from said received signal;complex despreading means generating a despread signal at bit rate N*D from said demodulated signal;means for summing over N samples generating a summed signal at bit rate D from said despread signal;a loop for estimating and correcting the phase shift induced in said demodulated signal, said loop comprising:means for sampling the argument of said summed signal;means for applying a predetermined function for moving the argument of the summed signal into a range of less than or equal to -.pi./(2x) but less than .pi.(2x), where x is equal to 1 or 2 according to whether said input signal is real or complex, the result of application of said predetermined function to said argument of the summed signal constituting an estimate of said phase shift;means for subtracting said estimate of the phase shift from the phase of said demodulated signal or from that of said despread signal; andregenerating means for regenerating said input signal from said summed signal, said regenerating means comprising means for resolving a residual static phase ambiguity induced by application of said predetermined function.