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A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model

Global Navigation Satellite Systems (GNSS) have been widely used in navigation, positioning and timing. Nowadays, the multipath errors may be re-utilized for the remote sensing of geophysical parameters (soil moisture, vegetation and snow depth), i.e., GPS-Multipath Reflectometry (GPS-MR). However,...

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Autores principales: Wu, Xuerui, Jin, Shuanggen, Xia, Junming
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5492165/
https://www.ncbi.nlm.nih.gov/pubmed/28587255
http://dx.doi.org/10.3390/s17061291
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author Wu, Xuerui
Jin, Shuanggen
Xia, Junming
author_facet Wu, Xuerui
Jin, Shuanggen
Xia, Junming
author_sort Wu, Xuerui
collection PubMed
description Global Navigation Satellite Systems (GNSS) have been widely used in navigation, positioning and timing. Nowadays, the multipath errors may be re-utilized for the remote sensing of geophysical parameters (soil moisture, vegetation and snow depth), i.e., GPS-Multipath Reflectometry (GPS-MR). However, bistatic scattering properties and the relation between GPS observables and geophysical parameters are not clear, e.g., vegetation. In this paper, a new element on bistatic scattering properties of vegetation is incorporated into the traditional GPS-MR model. This new element is the first-order radiative transfer equation model. The new forward GPS multipath simulator is able to explicitly link the vegetation parameters with GPS multipath observables (signal-to-noise-ratio (SNR), code pseudorange and carrier phase observables). The trunk layer and its corresponding scattering mechanisms are ignored since GPS-MR is not suitable for high forest monitoring due to the coherence of direct and reflected signals. Based on this new model, the developed simulator can present how the GPS signals (L1 and L2 carrier frequencies, C/A, P(Y) and L2C modulations) are transmitted (scattered and absorbed) through vegetation medium and received by GPS receivers. Simulation results show that the wheat will decrease the amplitudes of GPS multipath observables (SNR, phase and code), if we increase the vegetation moisture contents or the scatters sizes (stem or leaf). Although the Specular-Ground component dominates the total specular scattering, vegetation covered ground soil moisture has almost no effects on the final multipath signatures. Our simulated results are consistent with previous results for environmental parameter detections by GPS-MR.
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spelling pubmed-54921652017-07-03 A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model Wu, Xuerui Jin, Shuanggen Xia, Junming Sensors (Basel) Article Global Navigation Satellite Systems (GNSS) have been widely used in navigation, positioning and timing. Nowadays, the multipath errors may be re-utilized for the remote sensing of geophysical parameters (soil moisture, vegetation and snow depth), i.e., GPS-Multipath Reflectometry (GPS-MR). However, bistatic scattering properties and the relation between GPS observables and geophysical parameters are not clear, e.g., vegetation. In this paper, a new element on bistatic scattering properties of vegetation is incorporated into the traditional GPS-MR model. This new element is the first-order radiative transfer equation model. The new forward GPS multipath simulator is able to explicitly link the vegetation parameters with GPS multipath observables (signal-to-noise-ratio (SNR), code pseudorange and carrier phase observables). The trunk layer and its corresponding scattering mechanisms are ignored since GPS-MR is not suitable for high forest monitoring due to the coherence of direct and reflected signals. Based on this new model, the developed simulator can present how the GPS signals (L1 and L2 carrier frequencies, C/A, P(Y) and L2C modulations) are transmitted (scattered and absorbed) through vegetation medium and received by GPS receivers. Simulation results show that the wheat will decrease the amplitudes of GPS multipath observables (SNR, phase and code), if we increase the vegetation moisture contents or the scatters sizes (stem or leaf). Although the Specular-Ground component dominates the total specular scattering, vegetation covered ground soil moisture has almost no effects on the final multipath signatures. Our simulated results are consistent with previous results for environmental parameter detections by GPS-MR. MDPI 2017-06-05 /pmc/articles/PMC5492165/ /pubmed/28587255 http://dx.doi.org/10.3390/s17061291 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Wu, Xuerui
Jin, Shuanggen
Xia, Junming
A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model
title A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model
title_full A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model
title_fullStr A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model
title_full_unstemmed A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model
title_short A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model
title_sort forward gps multipath simulator based on the vegetation radiative transfer equation model
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5492165/
https://www.ncbi.nlm.nih.gov/pubmed/28587255
http://dx.doi.org/10.3390/s17061291
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