Patent ID: 7729455

Claim:
A phase-shift keying (PSK) receiver, comprising: a quadrant determining circuit that determines a quadrant on an I-Q constellation where a phase point defined by 1-bit digital signals respectively corresponding to an in-phase component I and an quadrature component Q included in a received signal exists; a rotating direction determining circuit that determines rotating direction of the phase point defined by the in-phase component I and the quadrature component Q included in the received signal; an IQ determining circuit that compensates the in-phase component I and the quadrature component Q by determining whether the in-phase component I and the quadrature component Q included in the received signal are right or not on the basis of the determination result in the quadrant determining circuit and the rotating direction determining circuit; a state determining circuit that determines position on the I-Q constellation of the phase point; and a determining circuit that demodulates the received signal on the basis of the compensation result in the IQ determining circuit and the determination result in the state determining circuit, wherein the state determining circuit divides the I-Q constellation into a first domain including a first quadrant and a third quadrant excluding predetermined range from I axis and Q axis, on a second domain including a second quadrant and a fourth quadrant excluding the predetermined range from the I axis and Q axis, on a third domain including the predetermined range from the Q axis, and on a fourth domain within the predetermined range from the I axis, wherein the in-phase component I and the quadrature component Q included in the received signal are not matched, the state determining circuit determines that the present domain of the phase points is changed to the next domain along the rotating direction determined by the rotating direction determining circuit, and wherein the state determining circuit stops observing the quadrant on which the corresponding phase point stays at the moment after the time while the state determining circuit continues to observe passes, and outputs the determination result representing the domain on which the corresponding phase point stay, on the basis of the observation result during the observing time after waiting time of waiting the output of the determination result passes.