A study on FFT-based coherent frequency hopping technique

We propose a new coherent frequency hopping (FH) technique for use in FH spread spectrum (FHSS) satellite communication system by employing double-dwell code acquisition and fast Fourier transform (FFT) based frequency synthesizer. In order to resolve the phase discontinuity (i.e., noncoherence) of the FH synthesizer as well as the error in the recovered hop timing, we propose FFT-based frequency synthesizer with proper code acquisition scheme. Then we analyze the performance of the coherent slow-FH QPSK and noncoherent slow-FH 4FSK. Simulation result shows that our proposed coherent FH QPSK system improves the bit-error-rate (BER) performance significantly