Decision rules applied to spread spectrum signal detection

Decision rules for detection of spread spectrum signals were investigated. For each decision rule, error and erasure probabilities were analyzed. The obtained data was used to plot P sub E vs. P sub E for constant signal-to-noise ratio (SNR). With the use of the probability-of-a-word-error curves the optimum threshold setting was found for a given SNR. Orthogonal signalling (FSK) and antipodal signalling (PSK) were considered for modulating the chips. When the P sub E vs. P sub E plots for FSK and PSK were compared, PSK performed better than FSK by a ratio of 6 dB. Finally, analog and digital correlation of the received signals was investigated. Compared to the performance of analog correlation, the system performance for digital correlation was worse by less than 1 dB.