Performance of sequential detectors for the acquisition of data modulated spread spectrum pseudo noise signals

The problem of fast initial acquisition of spread-spectrum pseudo-noise (PN) sequence synchronization in low SNR conditions is addressed. The sequential detector offers optimum performance by minimizing the time taken to eliminate the wrong code epochs for a given probability of detection and false alarm in a serial search strategy, but its analysis using analytical techniques is extremely complex. The effect of data modulation on the acquisition performance of several sequential detectors is obtained using a Monte Carlo computer simulation technique. The effects of data modulation on the quantized log-likelihood sequential detector and biased square law device are compared with the ideal log-likelihood sequential detector for moderate predetection SNRs (in the range -4 dB to 10 dB)