A novel FSK demodulation method using the short-time DFT analysis for LEO satellite communications systems

This paper proposed a novel and simple frequency shift keying (FSK) demodulation method using the short time discrete Fourier transform (ST-DFT) analysis for low Earth orbit (LEO) satellite communications systems. The ST DFT FSK demodulation method is potentially robust to a large and time variant frequency offset caused by the Doppler effect, because it can demodulate the received signal only by searching for the instantaneous energy spectral peak without a complicated carrier recovery circuit and it is insensitive to the signal to noise power ratio (SNR) degradation caused by the excessively wide bandwidth of the receiver front-end band pass filter. Furthermore, the ST DFT FSK demodulation method using the frequency sequence estimation (FSE) based on the Viterbi algorithm can significantly improve the bit error for the large and time variant frequency offset