caa a22 4500 606162607 CHVBK 20210128100640.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s10291-014-0385-5 doi (NATIONALLICENCE)springer-10.1007/s10291-014-0385-5 Improved FLL-assisted PLL with in-phase pre-filtering to mitigate amplitude scintillation effects [Elektronische Daten] [Rui Xu, Zhizhao Liu, Wu Chen] Ionospheric scintillation can increase carrier tracking error of the Global Positioning System (GPS) receiver and may lead to loss of lock under serious conditions. It is a threat to reliable and accurate GPS applications. Kalman filter-based phase lock loop, frequency lock loop-assisted phase lock loop (FAP) and vector-based tracking algorithms are considered as solutions to improve the robustness of carrier tracking. However, their performances are sensitive to loop parameters: noise bandwidth and integration period. We analyze the effects of amplitude scintillation on inputs signals, in-phases and quadra-phases, of carrier tracking loop. Analysis result shows amplitude scintillations affect in-phase much more seriously than quadra-phase. Based on the results, the FAP with in-phase pre-filtering (FAP_IPF) method is proposed to mitigate the amplitude scintillation effect on in-phase. IPF is placed before discriminators of FAP to restrict the in-phase variation within a reasonable range. The tracking loop FAP_IPF is tested using both simulated and real-world GPS intermediate frequency (IF) data with amplitude scintillation and compared to the traditional third-order PLL and FAP without IPF. The tracking results show that FAP_IPF is more robust than FAP and traditional PLL. In 10 simulation scintillation cases (S 4=0.6-1.0 and C/N0=40dB-Hz), FAP_IPF can maintain tracking in 6-9 cases even if its bandwidth Bn varies in a large range 7.5-15Hz. FAP has the best performance at bandwidth Bn=10Hz, but its performance is degraded dramatically at other bandwidths. PLL shows the worst performance among the three algorithms. In real-world GPS IF data with real-world scintillation S 4=1.11 and σ ϕ =1.49rad, FAP_IPF can successfully maintain signal tracking within bandwidth Bn=7.5-12.5Hz, while both FAP and traditional PLL lose signal trackings. Springer-Verlag Berlin Heidelberg, 2014 Ionospheric amplitude scintillation nationallicence FLL-assisted PLL nationallicence In-phase pre-filtering nationallicence Xu Rui Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong aut Liu Zhizhao Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong aut Chen Wu Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong aut GPS Solutions Springer Berlin Heidelberg 19/2(2015-04-01), 263-276 1080-5370 19:2<263 2015 19 10291 https://doi.org/10.1007/s10291-014-0385-5 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10291-014-0385-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Xu Rui Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong aut NATIONALLICENCE 700 1- Liu Zhizhao Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong aut NATIONALLICENCE 700 1- Chen Wu Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong aut NATIONALLICENCE 773 0- GPS Solutions Springer Berlin Heidelberg 19/2(2015-04-01), 263-276 1080-5370 19:2<263 2015 19 10291