Noise performance of a matched filter PN code synchroniser using a maximum likelihood detector

Using a computer simulation, this paper compares the acquisition performance of a digital matched filter PN code synchroniser, based on a simple threshold detector, with that using a maximum likelihood detector under conditions of additive Gaussian noise. Both types of synchroniser have a hard-limiter at their input. It is found that the conventional digital matched filter synchroniser has excellent acquisition performance in relatively good to moderately poor input SNRs, but fails as the input SNR falls below a 'threshold' SNR, whereas the maximum likelihood detector system has good acquisition performance over a much wider range of input SNR, even with data modulation.