Design of Narrowband Anti-jamming GPS Receivers in Time Domain
| Autor: | Tei-Pei Liu, 劉德培 |
|---|---|
| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 The globe position system (GPS) can provide accurate positioning and timing information useful in many applications. The communication technology used in GPS is a direct sequence spread spectrum (DS-SS) structure. Using C/A Gold codes, it can cope with wideband noise (such as thermal noise and channel noise) or low power narrowband interference by its processing gain. But DS-SS can not reject high power narrowband interference completely. So we need an anti-jamming filter to reject the narrowband interference by using adaptive filters prior to dispreading. This paper proposed a fixed-point transversal adaptive filter and a fixed-point lattice adaptive filter for the application in GPS anti-jamming system. Four types of narrowband jammers, i.e. continuous wave interference (CWI), multi-tone CWI, swept CWI, and pulsed CWI, are considered in order to emulate realistic conditions. As the jammings are unknown, the adaptive predictor is employed to accurately predict the narrowband signals based on a real-time learning method. In order to compare the two kinds of anti-jamming filter, we need simulation. Simulation results show that the proposed methods achieve good performance in terms of SNR improvement in broad class of interference environments. Finally, we implement the transversal anti-jamming filter in FPGA. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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