Computer simulation of a quantized log-likelihood sequential detector for faster acquisition of spread spectrum pseudo-noise signals

Presents the performance of a quantized log-likelihood sequential detector for the acquisition of pseudo-noise signals in direct-sequence spread spectrum systems. This new sequential detector improves the ease of implementation through the use of a digitally implementable look-up table approach, and it also simultaneously provides the minimum mean acquisition time for a lower input signal-to-noise (SNR) ratio when compared with a fixed dwell serial-search or matched filter acquisition system. The effect of the number of quantization levels on the acquisition performance of the quantized log-likelihood sequential detector has been obtained by computer simulation and compared with the performance of a sequential detector employing an ideal log-likelihood function. It has been found that the quantized log-likelihood sequential detector with 32 quantization levels yields an acquisition performance close to the ideal sequential detector. Optimization of various sequential detector system parameters to result in the minimum mean acquisition time has also been discussed