Adaptive SNR-based carrier phase multipath mitigation technique

1998 ◽  
Vol 34 (1) ◽  
pp. 264-276 ◽  
Author(s):  
C.J. Comp ◽  
P. Axelrad
Keyword(s):  
Carrier Phase ◽  
Multipath Mitigation ◽  
Mitigation Technique

scholarly journals The carrier-multipath observable: a new carrier-phase multipath mitigation technique

GPS Solutions ◽  
2014 ◽  
Vol 19 (1) ◽  
pp. 73-82 ◽  
Author(s):  
Ramin Moradi ◽  
Wolfgang Schuster ◽  
Shaojun Feng ◽  
Altti Jokinen ◽  
Washington Ochieng
Keyword(s):  
Carrier Phase ◽  
Multipath Mitigation ◽  
Mitigation Technique

Multi-GNSS Slant Wet Delay Retrieval Using Multipath Mitigation Maps

2021 ◽  
Author(s):  
Addisu Hunegnaw ◽  
Yohannes Getachew Ejigu ◽  
Felix Norman Teferle ◽  
Gunnar Elgered
Keyword(s):  
Carrier Phase ◽  
Positive Impact ◽  
Parameter Estimates ◽  
Multipath Mitigation ◽  
Unknown Parameters ◽  
Near Surface ◽  
Horizontal Gradients ◽  
Station Coordinates ◽  
Multipath Effects ◽  
Gnss Processing

<p>The conventional Global Navigation Satellite System (GNSS) processing is typically contaminated with errors due to atmospheric variabilities, such as those associated with the mesoscale phenomena. These errors are manifested in the parameter estimates, including station coordinates and atmospheric products. To enhance the accuracy of these GNSS products further, a better understanding of the local-scale atmospheric variability is necessary. As part of multi-GNSS processing, station coordinates, carrier phase ambiguities, orbits, zenith total delay (ZTD) and horizontal gradients are the main parameters of interest. Here, ZTD is estimated as the average zenith delay along the line-of-sight to every observed GNSS satellite mapped to the vertical while the horizontal gradients are estimated in NS and EW directions and provide a means to partly account for the azimuthally inhomogeneous atmosphere. However, a better atmospheric description is possible by evaluating the slant path delay (SPD) or slant wet delay (SWD) along GNSS ray paths, which are not resolved by ordinary ZTD and gradient analysis. SWD is expected to provide better information about the inhomogeneous distribution of water vapour that is disregarded when retrieving ZTD and horizontal gradients. Usually, SWD cannot be estimated directly from GNSS processing as the number of unknown parameters exceeds the number of observations. Thus, SWD is generally calculated from ZTD for each satellite and may be dominated by un-modelled atmospheric delays, clock errors, unresolved carrier-phase ambiguities and near-surface multipath scattering.</p><p> </p><p>In this work, we have computed multipath maps by stacking individual post-fit carrier residuals incorporating the signals from four GNSS constellations, i.e. BeiDou, Galileo, Glonass and GPS. We have selected a subset of global International GNSS Service (IGS) stations capable of multi-GNSS observables located in different climatic zones. The multipath effects are reduced by subtracting the stacked multipath maps from the raw post-fit carrier phase residuals. We demonstrate that the multipath stacking technique results in significantly reduced variations in the one-way post-fit carrier phase residuals. This is particularly evident for lower elevation angles, thus, producing a retrieval method for SWD that is less affected by site-specific multipath effects. We show a positive impact on SWD estimation using our multipath maps during increased atmospheric inhomogeneity as induced by severe weather events.</p>

Assessment of wavelets analysis for carrier-phase multipath mitigationThis article is one of a series of papers published in this Special Issue on the theme GEODESY.

2009 ◽  
Vol 46 (8) ◽  
pp. 627-636
Author(s):  
Ahmed A. El-Ghazouly ◽  
Mohamed Elhabiby ◽  
Naser El-Sheimy
Keyword(s):  
Carrier Phase ◽  
Deformation Monitoring ◽  
Double Difference ◽  
Multipath Mitigation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Adaptive Wavelet ◽  
Multipath Error ◽  
Phase Measurements ◽  
Search Volume

In carrier-phase measurements, which are the most precise observations for Global Positioning System (GPS) relative positioning, multipath error is still a factor that interferes with achieving the desired accuracy. Various improvements in receiver and antenna technologies, as well as modeling strategies, have resulted in better ways of coping with this error source. However, errors caused by multipath can be as large as 5 cm, which is not an acceptable accuracy, especially in precise surveying applications like deformation monitoring. In this paper, a full assessment of different wavelets techniques that can be used in multipath mitigation is made to evaluate the optimum way of using wavelets to reduce or remove this type of error. Also, a new approach based on the wavelet detrending technique is introduced to remove carrier-phase multipath error in the measurement domain. To mitigate multipath, GPS double-difference observables are fed to an adaptive wavelet analysis procedure based on high- and low-pass filter decomposition with different levels of resolution. Consequently, the observable sequences are corrected; these corrected observables can then be used to reduce the ambiguity search volume during the initial float solution stage. Meanwhile, double-difference observations with multipath mitigation offer an efficient method for obtaining a better baseline solution.

scholarly journals A GPS multipath mitigation technique using correlators with variable chip spacing

2019 ◽  
Vol 94 ◽  
pp. 03006
Author(s):  
Jin Hyuk Lee ◽  
Deok Won Lim ◽  
Jae Hee Noh ◽  
Gwang Hee Jo ◽  
Chansik Park ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Tracking Error ◽  
Integration Time ◽  
Software Platform ◽  
Multipath Mitigation ◽  
Code Tracking ◽  
Similar Performance ◽  
Multipath Signals ◽  
Mitigation Technique

Various methods have been studied to mitigate the influence of multipath signals, representative methods focused the correlator structure are the Narrow Correlator and the Multipath Elimination Technique (MET). It is known that the MET has better performance than Narrow Correlator but it requires more complexity. In this paper, we propose a technique that has similar performance to the MET and it uses only three correlators like the Narrow Correlator. This technique switches the chip spacing of the correlators for each Predetection Integration Time (PIT) and applies it to the MET. For the performance analysis, we implemented a software platform and compared the code tracking error of the proposed technique with that of the Narrow Correlator and the MET.

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