Efficient Folding Processor for Direct Precision Code Acquisition in Global Positioning System Sensors

Abstract

Although the folding processor enables the global positioning system (GPS) sensor to directly acquire the correct phase of the received precision code (P code) without any prior information on the phase from auxiliary codes such as the coarse acquisition code, the output of the folding processor essentially involves considerable out-of-phase components as a result of multiple phases being used all together in the folding processor, and consequently, it could result in a poor acquisition performance. Thus, in this study, a novel folding processor is designed to reduce the number of out-of-phase components while maintaining the desirable in-phase components, thus achieving a better acquisition performance. In addition, the proposed folding processor does not require the parallel correlator used in the conventional folding processor, thus lowering the complexity in implementation. Numerical results demonstrate that the proposed folding processor provides a significant improvement in acquisition over the conventional folding processor, with a lower complexity in implementation.