Modulation index estimation for CPFSK signals and its application to timing synchronization

Modulation index is an important parameter of CPFSK (continuous phase frequency shift keying) signals, which affects the system performance significantly. In noncooperative communication systems, this index is unknown to the receiver and must be estimated. This paper proposed a fast modulation index estimation algorithm for CPFSK signals based on short time Fourier transform (STFT). Simulations show the estimation results fit the actual value well. Furthermore, this paper evaluated the performance of timing synchronization and BER using the estimated modulation index, which is near to the performance using the real index.