PI/4 SHIFT QPSK MODULATION-DEMODULATION SYSTEM

摘要

PURPOSE:To realize the demodulation in the pi/4 shift QPSK system having a BER characteristic equal to the QPSK characteristic. CONSTITUTION:A burst data comprising two sets of data of an odd number and even number of strings subject to alternate differential phase modulation for each symbol and preamble inserted to a head of the data while being split into two symbols to decide the phase of the data is modulated by a QPSK carrier whose phase is shifted by pi/4 at a sender side, and the modulated data is sent. A phase detector circuit 2 detects a phase at a receiver side by using the reception signal and a signal resulting from delaying the reception signal by a 2-symbol delay device 1.