Pulse or digital communications – Receivers – Angle modulation
Patent
1993-07-27
1995-05-02
Chin, Stephen
Pulse or digital communications
Receivers
Angle modulation
329306, 375327, 375344, 375343, H04L 2714, H04L 2716, H04L 2722
Patent
active
054126932
ABSTRACT:
The present invention relates to a QAM signal demodulation system able to recover phase and frequency of the carrier and convert the signal to baseband, and to perform these functions when frequency errors are remarkable with respect to the symbol frequency (low capacity links); to reconstruct the synchronism of symbol in order to correctly sampling the analog signal to be processed; to complete the shaping of the signal through a digital filter and to equalize the baseband converted signal (in order to compensate the selective fading effects due to propagation and the linear distortions due to imperfections in the realization of the apparatus). Therefore the system comprises several subsystems devoted to performing the various functions and, in particular, at least a carrier frequency and phase recovery subsystem, a subsystem for reconstructing the synchronism frequency capable of driving the signal sampling circuit, and a subsystem of filters. The present invention is directed to the choice of the particular subsystems used as well as their implementation and interconnections.
REFERENCES:
patent: 4262360 (1981-04-01), Bigo et al.
patent: 4320517 (1982-03-01), Godard et al.
patent: 4527278 (1985-07-01), Deconche et al.
patent: 4737728 (1988-04-01), Nakamura et al.
patent: 4879728 (1989-11-01), Tarallo
Electronics and Communication Journal, vol. 3, No. 6, Dec. 1991, London GB, pp. 291-298--Fines and Aghvami `Fully digital M-ary PSK and M-ary QAM demodulators for land mobile satellite communications`, FIGS. 2, 3, 5.
Bolla Maurizio
Gelichi Massimo
Guglielmi Franco
Leuratti Nino
Alcatel Italia S.P.A.
Chin Stephen
Vo Don
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