Effect of noise on the acquisition performance of a delay lock look synchronizer used in CDMA applications

Considers the problem of initial acquisition of pseudonoise code synchronization in the presence of noise for direct-sequence spread-spectrum systems using a delay lock loop. A computer simulation of an mΔ delay lock loop has been developed based on its phase-plane acquisition trajectory and subject to the effects of additive Gaussian noise on the VCO error signal. Results are obtained for a 2Δ loop which show how external noise superimposed on the wanted signal affects the probability of initial acquisition of phase synchronization. In particular, the effect of the initial search rate on the probability of lock is considered as a function of both noise on the discriminator characteristics and phase jitter. It is found that there is an optimum search rate which maximises the probability of lock for a given signal to noise ratio