Patent ID: 6717993
Filing Date: 2004-04-06
Classification: H04L

Abstract:
A receiver comprising:demodulating means for demodulating a signal to be PSK-modulated in which digital signals modulated by a plurality of PSK modulation systems having a different number of phases are time-multiplexed by using carrier waves regenerated by carrier-wave regenerating means and outputting symbol data; received-signal-phase-rotation-angle detecting means for detecting a phase rotation angle of each symbol data output from the demodulating means against the transmission side; inversely-phase-rotating means for inversely rotating the phase of each symbol data output from the demodulating means by a phase rotation angle detected by the received-signal-phase-rotation-angle detecting means and thereby, absolute-phase-generating the phase of each symbol data and outputting the phase; and modulation-system identifying means for identifying a modulation system currently demodulated by the demodulating means; characterized in that the inversely-phase-rotating means rotates the phase of each symbol data output from the demodulating means by two types of phase rotation angles through time sharing and outputs the phase rotation angles and one of the two types is equal to the inverse phase rotation angle, the carrier-wave regenerating means is provided with a phase error table storing carrier-wave phase error data for various symbol data after absolute-phase-generated according to the PSK modulation system having the minimum number of phases and phase-error detecting means for detecting a phase error of a regenerated carrier wave by obtaining a shift angle up to a target phase convergent angle of a received-signal point shown by the absolute-phase-generated symbol data for each symbol viewed in the positive direction or negative direction of I-axis included in a phase error table according to a modulation system identified by the modulation-system identifying means and reading carrier-wave phase error data corresponding to symbol data inversely phase-rotated by an angle corresponding to the sum of the other phase rotation angle of the two types of phase rotation angles of each symbol data and a shift angle up to a target phase convergent angle against the transmission side phase-rotated by the inversely-phase-rotating means through the time sharing out of a phase error table, and a phase of a regenerated carrier wave is corrected in accordance with the carrier-wave phase error data detected by the phase-error detecting means.