Compared performances of trellis coded QDPSK modulation and CPFSK modulation with discrimination detection

The performance of a trellis coded four phase differential phase shift keying (TC QDPSK) modem with symbol decoding is compared with a continuous phase frequency shift keying (CPFSK) modem using noncoherent detection. The bit error rate (BER) performance as a function of signal-to-noise ratio per bit is obtained by simulation of both systems. It is shown that the trellis coded system provides a better BER performance for a given signal-to-noise ratio per bit. The bandwidth requirements for both systems are analyzed and compared. The TC 4DPSK system trades off part of the maximum achievable coding gain for a simpler implementation.<>