Digital cellular system with linear modulation

The authors describe a digital cellular system with linear modulation. They discuss two kinds of modulation schemes-QPSK (quadrative phase-shift keying) and pi /4 shift QPSK, and two kinds of detection schemes-coherent detection and limiter-discriminator detection. The features of these modulation/detection schemes are clarified. From the collective point of view, the pi /4 shift QPSK/limiter-discriminator detection is judged to be the most advantageous. Next, the authors show examples of the radio link design for a digital cellular system with linear modulation. The system could be constructed at a transmission power of 100-200 mW. Finally, the breadboard equipment configuration and the experimental results are shown. >