A pi /4-shifted DQPSK demodulator for a personal mobile communications system
Hidemitsu Furukawa, 幸二 松山, Takashi G. Sato, T. Takenaka, Yohsuke Takeda · 2003
A digital 384-kbps TDMA-TDD microcellular system using pi /4-shifted DQPSK modulation is under development in Japan. To simplify the demodulator's configuration using this system and to reduce its power consumption, the authors propose a pi /4-shifted DQPSK demodulator that includes what they call an arctangent differential detector (ATN-DD) and an arctangent automatic frequency controller (ATN-AFC) because they process the phase of the received signal rather than the quadrature components. They present the configuration and the principles of operation of the ATN-DD and the ATN-AFC and show the results of BER and AFC performance testing. In addition, they investigate the most suitable AFC structure. Their study enabled a differential detector and AFC circuit gate-count reduction of more than 60%.>