A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model
| Autor: | Shuanggen Jin, Xuerui Wu, Junming Xia |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010504 meteorology & atmospheric sciences
0211 other engineering and technologies 02 engineering and technology GPS signals 01 natural sciences Biochemistry Article Physics::Geophysics Analytical Chemistry vegetation medicine Radiative transfer Coherence (signal processing) Electrical and Electronic Engineering Instrumentation radiative transfer equation model Simulation 021101 geological & geomatics engineering 0105 earth and related environmental sciences Remote sensing GNSS-R business.industry multipath simulation Pseudorange Atomic and Molecular Physics and Optics GNSS applications Global Positioning System medicine.symptom Vegetation (pathology) business Geology Multipath propagation |
| Zdroj: | Sensors (Basel, Switzerland) Sensors; Volume 17; Issue 6; Pages: 1291 |
| ISSN: | 1424-8220 |
| DOI: | 10.3390/s17061291 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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