DIGITAL COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To increase a transmission amount by validating signal arrangement points not in use in theπ/4 shift QPSK modulation system. SOLUTION: A synthesizer 5 synthesizes signals of theπ/4 shift QPSK modulation system outputted from two independent equivalent transmission systems synchronized with each other using a same frequency, and transmits the synthesized signal as an output signal. A receiver side demodulates the synthesized signal into a bit string based on phase and amplitude information. The signal arrangement points not in use in theπ/4 shift QPSK modulation system are used effectively to double the transmission capacity by synthesizing the signals from the two independent equivalentπ/4 shift QPSK modulators 2 synchronized with each other.