A New Method for GNSS Multipath Mitigation with an Adaptive Frequency Domain Filter

Multipath is the dominant error source for most fixed Global Navigation Satellite Systems (GNSS) sites and stations. The presence of multipath, particularly the multipath effect on pseudorange measurement, seriously affects positioning accuracy. Unfortunately, multipath effect reduction is still a challenging issue in high-accuracy GNSS positioning applications due to its special properties. To minimize the impact of the multipath effect, this paper focused on pseudorange multipath mitigation. First, the frequency spectrum of the code-minus-carrier divergence (CMCD) for Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and BeiDou Navigation Satellite System (BDS) satellites observed in different environments were analyzed, where we found that periodic fluctuations appeared in GPS and GLONASS as well as medium earth orbit (MEO) and inclined geosynchronous satellite orbit (IGSO) of BDS satellites in some situations, which manifested as peaks in the frequency domain. The results showed that the location of the frequency peaks in the frequency domain, width, and basic frequency spectrum intensity were different between different satellites and environments, causing difficulty in reducing the error impact. To eliminate such period fluctuations mainly caused by the multipath effect, a novel method based on a frequency domain filter was proposed in this paper. One of the keys of the proposed method was the use of short-time Fourier transformation (STFT) in the GNSS signal data processing to calculate the accurate local frequency spectrum when code-minus-carrier divergence (CMCD) was assumed to be time varying. Once the frequency spectrum was obtained, a new spectrum peak extraction method was used to locate the peak frequency position. By interpolation and inverse Fourier transformation, the influence of the spectrum peaks could be effectively eliminated, thus improving pseudorange precision. The experimental results showed that the periodic multipath effect could be greatly reduced by the proposed method.

[1]  David H. Bailey,et al.  A Fast Method for the Numerical Evaluation of Continuous Fourier and Laplace Transforms , 1994, SIAM J. Sci. Comput..

[2]  Wang Zhi-jie.  Study on Low-pass Filter Based GPS/INS Integrated Navigation Model , 2013 .

[3]  Letizia Lo Presti,et al.  Effects of colored noise in Linear Adaptive Filters applied to GNSS multipath detection , 2013, 2013 Conference on Design and Architectures for Signal and Image Processing.

[4]  Patrick C. Fenton,et al.  A Practical Approach to the Reduction of Pseudorange Multipath Errors in a Ll GPS Receiver , 1994 .

[5]  Denghui Wang,et al.  Multipath extraction and mitigation for bridge deformation monitoring using a single-difference model , 2017 .

[6]  P. Barton,et al.  Reduction of tracking errors induced by multipath at low elevation angles , 1980 .

[7]  Guangfu Sun,et al.  Multipath detection based on single orthogonal dual linear polarized GNSS antenna , 2017, GPS Solutions.

[8]  Z. Y. Wang,et al.  A sliding average Extended Kalman Filter and its application in multipath estimation , 2016, 2016 12th IEEE International Conference on Control and Automation (ICCA).

[9]  R. Bracewell.  The Fourier Transform and Its Applications , 1966 .

[10]  Zhen Wang,et al.  A Height Constrained Adaptive Kalman Filtering Based on Climbing Motion Model for GNSS Positioning , 2017, IEEE Sensors Journal.

[11]  M. Pinsky.  Introduction to Fourier analysis and wavelets , 2002 .

[12]  R. Hatch.  The synergism of GPS code and carrier measurements , 1982 .

[13]  Simon Haykin,et al.  Adaptive filter theory (2nd ed.) , 1991 .

[14]  James J. Spilker,et al.  GPS Signal Structure and Performance Characteristics , 1978 .

[15]  Yanyan Liu,et al.  Carrier phase multipath mitigation for BeiDou navigation satellite system , 2015, GPS Solutions.

[16]  Yanyan Liu,et al.  A geometry-free and ionosphere-free multipath mitigation method for BDS three-frequency ambiguity resolution , 2016, Journal of Geodesy.

[17]  M. Cannon,et al.  Mitigation of Static Carrier Phase Multipath Effects Using Multiple Closely-Spaced Antennas , 1998 .

[18]  Kenny C. S Kwok,et al.  Sidereal filtering based on single differences for mitigating GPS multipath effects on short baselines , 2010 .

[19]  Euiho Kim,et al.  Adaptive Carrier Smoothing Using Code and Carrier Divergence , 2007 .

[20]  Yujie Zhang,et al.  Multipath mitigation in the frequency domain , 2004, PLANS 2004. Position Location and Navigation Symposium (IEEE Cat. No.04CH37556).

[21]  B. Pervan,et al.  Code-Carrier Divergence Monitoring for the GPS Local Area Augmentation System , 2006, 2006 IEEE/ION Position, Location, And Navigation Symposium.

[22]  L. E. Young,et al.  GPS antenna selection: Preliminary range and field test results , 1988, 1988 Symposium on Antenna Technology and Applied Electromagnetics.

[23]  Jae S. Lim,et al.  Signal estimation from modified short-time Fourier transform , 1983, ICASSP.

[24]  J. J. Fourier,et al.  The Analytical Theory of Heat , 2009 .

[25]  Chris Rizos,et al.  Multipath Mitigation of Continuous GPS Measurements Using an Adaptive Filter , 2000, GPS Solutions.

[26]  A. J. Van,et al.  Theory and Performance of Narrow Correlator Spacing in a GPS Receiver , 1992 .

[27]  Gary A. McGraw,et al.  Generalized Divergence-Free Carrier Smoothing with Applications to Dual Frequency Differential GPS , 2009 .

[28]  S. Haykin,et al.  A new adaptive antenna for elevation angle estimation in the presence of multipath , 1980 .

[29]  Mohammad Reza Mosavi,et al.  A new method to mitigate multipath error in single-frequency GPS receiver with wavelet transform , 2013, GPS Solutions.

[30]  P. Seethalakshmi,et al.  Self-adaptable media service architecture for guaranteeing reliable multimedia services , 2010, Multimedia Tools and Applications.

[31]  Wan Abdul Aziz Wan Mohd Akib,et al.  The time series analysis in GPS structural monitoring schemes , 2002 .

[32]  Patrick C. Fenton,et al.  NOVATEL'S GPS RECEIVER THE HIGH PERFORMANCE OEM SENSOR OF THE FUTURE , 1991 .

[33]  Aydin Ustun,et al.  Detecting and removing repetitive errors from PPP time series by means of adaptive filter , 2017, 2017 Signal Processing Symposium (SPSympo).

[34]  Changdon Kee,et al.  Optimal Hatch Filter with an Adaptive Smoothing Window Width , 2008, Journal of Navigation.

[35]  Jorge L. Martínez,et al.  A new satellite selection criterion for DGPS using two low-cost receivers , 1998, Proceedings. 1998 IEEE International Conference on Robotics and Automation (Cat. No.98CH36146).

[36]  Lawrence Lau,et al.  Wavelet packets based denoising method for measurement domain repeat-time multipath filtering in GPS static high-precision positioning , 2017, GPS Solutions.

[37]  S. Haykin,et al.  Adaptive Filter Theory , 1986 .

[38]  Thomas Milligan,et al.  Method for Calculating Multipath Environment and Impact on GPS Receiver Solution Accuracy , 1996 .

[39]  Gang Xie,et al.  Optimal on-airport monitoring of the integrity of GPS-based landing systems , 2004 .

[40]  H. Al‐Rizzo,et al.  Analysis of a choke ring groundplane for multipath control in Global Positioning System (GPS) applications , 1994 .

[41]  Jing Xu,et al.  Adaptive Wavelet Threshold Denoising Method for Machinery Sound Based on Improved Fruit Fly Optimization Algorithm , 2016 .