PURPOSE: To improve pull-in characteristic and phase jitter characteristic by performing carrier reproduction control corresponding to all the input symbols.
CONSTITUTION: A complex multiplier 27 obtains quadiature detection output by multiplying quadrature amplitude modulated wave input by a reproducing carrier provided with quadrature phase relation with it. A phase and amplitude detector 28 obtains phase information and amplitude information by applying phase and amplitude detection to the quadrature detection output. A symbol estimation circuit 31 estimates the symbol of an input modulated wave from the phase information and the amplitude information. A phase error detection circuit 101 detects a phase error between the ideal phase of an estimated symbol and actual phase information, and controls the oscillation frequency of the reproducing carrier by the phase error. A decision circuit 44 decides the symbol of QPSK from the phase and amplitude information, and makes a hold circuit 41 hold the phase error signal at that time, and generates a signal to correct the phase reference axis of the symbol estimation circuit 3 via an LPF 42 and a switch 43.
ISHIKAWA TATSUYA
KOMATSU SUSUMU
TOSHIBA AVE KK