COMPARISON OF 4 FFT-BASED FREQUENCY ACQUISITION TECHNIQUES FOR COSTASLOOP BPSK SIGNAL DEMODULATION

This paper discussed four open-loop frequency acquisition techniques f or suppressed-carrier BPSK signals, The techniques, which do not requi re accurate symbol timing nor a data preamble sequence, employ fast Fo urier transforms (FFT's) on the Costas loop phase detector output to d etect the Doppler frequency offset. Performance of the full-, half-, a nd staggered-symbol integration techniques as well as the low-pass fil ter technique are compared in terms of the error signal output SNR's, Then, the probability of detecting the frequency offset is computed fo r the special case when the frequency of the tone to be detected coinc ides with one of the FFT-bin center frequencies, It is shown that the performance of the integration techniques depends strongly on the symb ol timing offset. On the other hand, the detection probability for the one-pole arm filter technique depends directly on the filter bandwidt h, The staggered integration technique Is shown to have comparable per formance to the lowpass filter technique for low-to-medium symbol SNR' s but the latter is superior at high symbol SNR's.