Design And Performance Validation Of The Interference-suppressing Software-defined GPS Receiver

The dissertation presents the research achievements focused on the technical solutions and implementations for an interference-suppressing software-defined GPS receiver.On the basis of introducing the methods for interference suppression used in GPS receiver, the techniques for interference suppression are selected for designing the receiver. The hardware and software units for the narrowband and multipath interference-suppressing software-defined GPS receiver are elaborated designed, and the mechanism of interference suppression in software unit is analyzed.The improved adaptive algorithm of filtering in frequency-domain is selected for the narrowband interference suppression according to the performance requirements; the improved early-late slope delay lock loop is selected for the multipath interference suppression according to the real-time requirement of the software unit and the performance. The difficulties of implementing those techniques on software-defined GPS receiver are researched, and some optimized methods are also used.With the clear target, the effects on GPS receiver caused by jamming are discussed, and how the errors are brought in by the multipath interference is analyzed, so the interference suppression methods are elicited according to the analyzed results. Three different code tracking loops which are used in software-defined GPS receiver are compared. The RF frontend and the interface parts in hardware unit are designed and illustrated. Then the key points focus on the software unit. The implement methods of the filtering in frequency-domain and the code tracking loop are improved and presented according to the analysis. And the interference suppressing methods used in signal acquisition and positioning are also presented, the flowcharts of the programs in the software unit are illustrated.The performance requirements are satisfied according to the field testing results of this software-defined GPS receiver The results of the emulation and actual tests show that this GPS receiver can carry out the narrowband and multipath interference suppression requirement.