Novel low cost direct sequence spread spectrum synchroniser

Abstract

Spread spectrum systems have become more and more popular, with many commercial systems appearing on the market. One of the more complicated areas of spread spectrum systems is code acquisition and tracking. Many acquisition and tracking methods have been presented in the literature. These various methods differ in complexity, performance and cost. We present a novel spread spectrum synchroniser that may be simpler and more cost effective than other synchronisation systems. Acquisition and tracking is achieved using one network, and the decision as to whether the system is in lock only occurs once the two sequences are aligned. No intermediate decision is required on the state of synchronisation. This feature of the synchroniser makes it cost effective and easy to implement. The drawback of having simplified the overall structure of the synchroniser is that the system requires a higher signal-to-noise ratio. This is a characteristic of systems requiring the detection of the incoming pseudo-noise sequence. One of the interesting aspects of the synchroniser is that the code-phase frequency grid is evaluated randomly as opposed to the deterministic evaluation by standard acquisition implementations.