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Multipath Detection and Mitigation Algorithm for Global Positioning System
Date Issued
2009
Date
2009
Author(s)
Chen, Min-Pei
Abstract
In Global Positioning System (GPS), many positioning errors such as clock error, tropospheric error and ionospheric error can be eliminated by using differential techniques. But characteristics of multipath interference depend on time and environment, which means that it can’t be canceled by differential technique. Therefore, multipath becomes one of the main error sources in GPS.ccording to the characteristics of multipath, this thesis proposes the multipath detection and multipath mitigation algorithm. The purpose of multipath detector is to determine whether a multipath is present. If multipath detector decides that a multipath is present, then the receiver may take some actions to mitigate multipath effect. The design issues of multipath detector contain selection of correlator spacing, taps of moving average filter and threshold setting. The influences of front-end RF filter and fixed-point effect are also analyzed. Simulation results show that the false alarm and miss detection probability of multipath detector are quite low. Moreover, the ability of real-time detection is very robust. For multipath mitigation, this thesis proposes a code discriminator to reduce multipath effect by means of increasing discriminator gain. In comparison with conventional narrow correlator, our proposed discriminator provides a 20% reduction in pseudorange error when the front-end RF bandwidth is 8.184 MHz and 56% when it is 16.368 MHz. However, the jitter when using this proposed discriminator is about 1.6 times larger than narrow correlator.
Subjects
multipath detection
cross-correlation distortion
threshold
multipath mitigation
discriminator
Type
thesis
File(s)
No Thumbnail Available
Name
ntu-98-R96942091-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):fd628566683b31d9177b28a176db6868