Spread-spectrum code and carrier synchronization errors caused by multipath and interference

The influence of multipath propagation and spread-spectrum interference on code and carrier synchronization is investigated. Both coherent and noncoherent delay lock loops (DLLs) are considered, with arbitrary early-late spacings up to one chip time. The coherent DLL is shown to have a major advantage; for a relatively high fading bandwidth, it has negligible tracking errors, while a noncoherent DLL always has a certain bias error. The results are particularly interesting for spread-spectrum positioning systems like Global Positioning System (GPS) and GLONASS.<
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