Carrier detection of direct sequence spread signals based on a delay-and-multiply device

Direct sequence spread spectrum signals are now widely used for communications, navigations systems and radar due to their low signal-to-noise ratios (SNR) and low probability of interception. However, spectrum surveillance of DSSS signals is difficult. Thus, a carrier detection method was developed based on delay-and-multiplication pre-filters. The relations between the delay, bandwidth and output SNR are used to identify the optimal system parameters. A theoretical analysis shows that with known partial parameters, the optimal detector is equivalent to the matched-filter energy detector with zero delay. With unknown parameters, the optimal bandwidth-delay product of the detector is 0.4. Simulations of the system performance with these settings verify the effectiveness of the method.