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Closed-loop joint code delay synchronization and carrier phase recovery for direct-sequence spread spectrum systems
Abstract
We propose a closed-loop system for acquisition of the pseudo-noise (PN) signal in direct-sequence spread-spectrum (DS/SS) systems. We introduce a novel idea of using an auxiliary signal, as opposed to the PN signal itself, for correlation with the incoming signal. The correlation function of the auxiliary signal and the PN signal has a triangle shape that covers essentially the entire period of the PN signal. Consequently, their correlation provides the direction for the phase update of the local signal generator in the acquisition scheme. With coherent demodulation, mean and variance of the acquisition time are derived. Results show that the proposed system acquires the PN phase at least twice faster, with significantly smaller acquisition time variance, than the conventional serial-search acquisition system. We propose a closed-loop system with a pre-loop code phase estimator for acquisition of the PN signal in DS/SS systems. The incoming signal is correlated with the auxiliary signal. The pre-loop code phase estimator uses the correlation result to estimate the incoming code phase. The closed-loop acquisition system starts with this initial estimate. With coherent demodulation, mean and variance of the acquisition time are derived. Results show that, with proper choices of parameters, the proposed system acquires the PN phase significantly faster than both the conventional serial-search system and the closed-loop system without the pre-loop estimator. We propose a closed-loop system for joint acquisition of the carrier phase and the PN signal phase in DS/SS systems. The system has a voltage-controlled-clock loop for PN phase acquisition and a voltage-controlled-oscillator loop for carrier phase acquisition. These loops work together and both loops use the auxiliary signal for correlation with the incoming signal. The correlator outputs provide the directions for the local code phase and the carrier phase updates. Mean and variance of the code phase acquisition time are derived. Results show that, the proposed system performs better than both the noncoherent and the coherent serial-search systems, and almost as good as the coherent closed-loop system.
Subject Area
Electrical engineering
Recommended Citation
Salih, Murat, "Closed-loop joint code delay synchronization and carrier phase recovery for direct-sequence spread spectrum systems" (1996). Doctoral Dissertations Available from Proquest. AAI9619432.
https://scholarworks.umass.edu/dissertations/AAI9619432