Low-complexity Solution to GPS Narrowband Interference Cancellation
Date Issued
2009
Date
2009
Author(s)
Huang, Yi-Cheng
Abstract
Nowadays GNSS (Global Navigation Satellite System) has been widely used in many places, for example, In-Car Navigation System, navigation on the sea, and so forth. Especially, there are more and more mobile phones that have navigation capability. And among all the navigation systems, GPS is the most widely used and well-known to people. GPS is the spread spectrum system and it has an advantage to resist the interference and jamming. But once the jamming power is too large, GPS still cannot work well. So, we must have anti-jamming techniques to overcome this problem. Traditionally, we usually deal with the interference or jamming from the time domain (FIR Filter) or frequency domain (FFT), but both the complexities are too high. So we try to find a low-complexity solution as long as the performance of the system is acceptable. In this thesis, we utilize an adaptive IIR notch filter to eliminate the narrowband interference. We use a simple algorithm to adaptively estimate the jamming frequency, and propose a method to estimate the jamming power. Furthermore, we propose a method to detect the jamming existence so that GPS signal will not attenuate by the notch filter once there is no jamming. We also analyze the group delay effect in the acquisition and tracking, and see the results caused by the multi-pole notch filter. Besides, we re-evaluated the proposed algorithms by using fixed-point analysis of IIR notch filter and adaptive algorithm.
Subjects
GNSS
all-pass based IIR notch filter
group delay
acquisition
tracking
AGC
Type
thesis
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