Filters








380 Hits in 3.0 sec

GPS Multipath Analysis Using Fresnel Zones

Florian Zimmermann, Berit Schmitz, Lasse Klingbeil, Heiner Kuhlmann
2018 Sensors  
Second, Fresnel zones are used to analyze the multipath induced by a horizontal and spatially-limited reflector.  ...  In this paper, the concept of Fresnel zones is applied to two different aspects of multipath. First, Fresnel zones are determined for the line-of-sight transmission between satellite and receiver.  ...  Abbreviations The following abbreviations are used in this manuscript: GNSS  ... 
doi:10.3390/s19010025 fatcat:mw3qgngfx5bslmzddebgftl4qe

Snow Depth Variations Estimated from GPS-Reflectometry: A Case Study in Alaska from L2P SNR Data

Shuanggen Jin, Xiaodong Qian, Hakan Kutoglu
2016 Remote Sensing  
However, most previous studies mainly used GPS L1C/A and L2C Signal-to-Noise Ratio (SNR) data to retrieve snow depth.  ...  The samplings of 15 s or 30 s have no obvious effect on snow depth estimation using GPS SNR L2P measurements, while the range of 5 ˝-35 ˝elevation angles has effects on results with a decreasing correlation  ...  Great appreciation is extended to the PBO for providing the GPS data and as well as to the Scientific Research Project Office of Bulent Ecevit University for support.  ... 
doi:10.3390/rs8010063 fatcat:4lrzbnumrzcelm3uqvhog3zc3m

Investigating GNSS multipath effects induced by co-located Radar Corner Reflectors

Thomas Fuhrmann, Matthew C. Garthwaite, Simon McClusky
2021 Journal of Applied Geodesy  
The effect depends on the GNSS antenna used at a site with the magnitude of multipath patterns being around three times smaller for a high-quality choke ring antenna compared to a ground plane antenna  ...  In general, the CR-induced multipath is small compared to multipath effects at other GNSS sites located in a different environment (e. g. mounted on a building).  ...  The GNSS sites used in this paper are operated by NSW Spatial Services and by Geoscience Australia.  ... 
doi:10.1515/jag-2020-0040 fatcat:sfy5gkqh2zdohh7e3qapnff3gu

GPS snow sensing: results from the EarthScope Plate Boundary Observatory

Kristine M. Larson, Felipe G. Nievinski
2012 GPS Solutions  
However, snow depth can only be estimated at GPS sites when the modulation frequency of multipath signals can be resolved.  ...  In particular, GPS sites in forested regions typically cannot be used for snow sensing. Multiple-year time series of snow depth are estimated from GPS sites in the Rocky Mountains.  ...  Larson used a Dean's Faculty Fellowship in 2011 to write the manuscript. All RINEX files used in this study are freely available from UNAVCO.  ... 
doi:10.1007/s10291-012-0259-7 fatcat:joed5ub4b5ae3jt4t7wfz2t32y

Using GPS multipath for snow depth sensing - first experience with data from permanent stations in Slovakia

Jan Hefty
2013 Acta geodynamica et geomaterialia  
Analysis of multipath reflections of GPS satellite signals at permanent GPS stations allows deducing the height of GPS antenna above the horizontal reflecting surface.  ...  If the effective height of the reflector is varying, e.g. due to change of snow cover in the vicinity of GPS antenna monumentation, the multipath characteristics are affected, namely the period of the  ...  First Fresnel zones for  =7° (red),  =10°(green) and  =25° (blue) are shown for observed satellites and azimuth sectors with reliable multipath reflections suitable for further analyses.  ... 
doi:10.13168/agg.2013.0055 fatcat:vfbyu6tmpjgh7ag2qt2v642yma

Quality control in GNSS reflectometry method for tide observations

Agung Syetiawan, Dudy Darmawan Wijaya, Irwan Meilano
2021 TELKOMNIKA (Telecommunication Computing Electronics and Control)  
The periodogram visualization can be used to decide which LSP is significant.  ...  The results using the data at Morotai station showed that the amplitude power less than 5 comes from low-frequency signals and hence it is an indicator that the Lomb-Scargle periodogram (LSP) fails to  ...  Based on the Fresnel zone mapping, the azimuth angles used in this study are within the ranges 0-20º and 200-360º, within which the signals contain multipath effects originating from the sea.  ... 
doi:10.12928/telkomnika.v19i6.21670 fatcat:somu4yqr75b6jjs5hy5s7igtfi

Software tools for GNSS interferometric reflectometry (GNSS-IR)

Carolyn Roesler, Kristine M. Larson
2018 GPS Solutions  
GNSS-R interferometric reflectometry (also known as GNSS-IR, or GPS-IR for GPS signals) is a technique that uses data from geodetic-quality GNSS instruments for sensing the near-field environment.  ...  Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creat iveco mmons .org/licen ses/by/4.0/), which permits unrestricted use,  ...  Two values of H R are used: 2 m (top) and 10 m (bottom) Fig. 2 Screenshot of first Fresnel zones for GNSS site P041.  ... 
doi:10.1007/s10291-018-0744-8 fatcat:zxvcassbjnfalbyvfm7hi7dx2q

The GPS Radio Occultation Technique

E. Robert Kursinski, George A. Hajj, Stephen S. Leroy, Benjamin Herman
2000 Terrestrial, Atmospheric and Oceanic Sciences  
In this paper we review the process of inverting the radio occultation observations ac quired using the Global Positioning System (GPS) in order to derive atmo spheric quantities of interest including  ...  Beginning with geometric optics, we derive the Abel integral used to transform the observations into profiles of refractivity.  ...  The required aperture would be one half the radius of the first Fresnel zone, roughly 350 m using GPS wavelengths.  ... 
doi:10.3319/tao.2000.11.1.53(cosmic) fatcat:yfvqpaxw5ng5nfqpgkf4wdlgfu

Sea level measurements using multi-frequency GPS and GLONASS observations

Johan S Löfgren, Rüdiger Haas
2014 EURASIP Journal on Advances in Signal Processing  
Global Positioning System (GPS) tide gauges have been realized in different configurations, e.g., with one zenith-looking antenna, using the multipath interference pattern for signal-to-noise ratio (SNR  ...  Both the SNR analysis and the phase delay analysis were evaluated using dual-frequency GPS and GLONASS signals, i.e., frequencies in the L-band, during a 1-month-long campaign.  ...  Acknowledgements The authors would like to thank Mattias Bermell Rudfelt, Daniel Hermansson, Annika Johansson, and Otto Torgnyson for their Bachelor thesis on analysis of SNR observations from GPS and  ... 
doi:10.1186/1687-6180-2014-50 fatcat:ttijtzjuefht5cgyk2cxqsjcai

A New GPS SNR-based Combination Approach for Land Surface Snow Depth Monitoring

Wei Zhou, Lilong Liu, Liangke Huang, Yibin Yao, Jun Chen, Songqing Li
2019 Scientific Reports  
In the current study, a new snow depth estimation approach is proposed using multipath reflectometry and SNR combination of GPS triple frequency (i.e. L1, L2 and L5) signals.  ...  Most studies only consider either global positioning system (GPS) L1 or L2 SNR data.  ...  The authors would like to thank the IGS Center for providing the GPS observations and the NCDC for providing the in situ snow depth data.  ... 
doi:10.1038/s41598-019-40456-2 pmid:30846763 pmcid:PMC6405773 fatcat:btazbidymrdz3eg5r7juvs22pa

Efficient Approach for International Space Station Global Positioning System Multipath Analysis

Shian U. Hwu, Robert J. Panneton, Susan F. Gomez
1997 Journal of Spacecraft and Rockets  
The alternate electric field peaks and valleys of the Fresnel zone phenomenon are observed in close range distances less than 40 m.  ...  P., “GPS Multipath Modeling and Verification Using Geometrical Theory of Diffraction,” Proceedings of ION GPS-95, Inst. of Navigation, Alexandria, VA, 1995, pp. 195-204. A. C.  ... 
doi:10.2514/2.3298 fatcat:bvfdiyln45fetpiuzoev5swnzm

GNSS-R with Low-Cost Receivers for Retrieval of Antenna Height from Snow Surfaces Using Single-Frequency Observations

Simone Rover, Alfonso Vitti
2019 Sensors  
However, in general, studies are being conducted using observations collected by continuously operating reference stations (CORS) built for geodetic purposes and equipped with geodetic-grade instruments  ...  The first Fresnel zone is the one that contributes most to the reflection of the incident signal.  ...  According to Equations (11) , the size of a Fresnel zone increases as the antenna height increases.  ... 
doi:10.3390/s19245536 pmid:31847416 pmcid:PMC6960877 fatcat:nmz3qstf7za7nji5sun5uds6ta

Monitoring Bare Soil Freeze–Thaw Process Using GPS-Interferometric Reflectometry: Simulation and Validation

Xuerui Wu, Shuanggen Jin, Liang Chang
2017 Remote Sensing  
Within the GPS-IR spatial resolution, one SNOTEL site (ID 958) and one corresponding PBO (plate boundary observatory) GPS site (AB33) are used for analysis.  ...  The corresponding theoretical simulation results from the forward GPS multipath simulator show variations of GPS multipath observables.  ...  At present, as for GPS-IR, it is thought that only the coherent scattering part at the first Fresnel Zone is received.  ... 
doi:10.3390/rs10010014 fatcat:exfnrgmtbzcv5ii5xsz5d3ae2u

Assessment of modernized GPS L5 SNR for ground-based multipath reflectometry applications

Sajad Tabibi, Felipe G. Nievinski, Tonie van Dam, João F.G. Monico
2015 Advances in Space Research  
Measurements from two GPS stations in Colorado, USA, were used to retrieve soil moisture and snow depth conditions.  ...  Previous GPS SNR multipath studies of soil moisture and snow depth have focused on the legacy GPS L1 and L2 bands.  ...  The GPS footprint for a ground-based antenna can be approximated as the first Fresnel zone, an ellipse dependent on the height of the antenna and the satellite elevation angle .  ... 
doi:10.1016/j.asr.2014.11.019 fatcat:stmcmymxrjgunk43zdysrjxaya

Using GPS multipath to measure soil moisture fluctuations: initial results

Kristine M. Larson, Eric E. Small, Ethan Gutmann, Andria Bilich, Penina Axelrad, John Braun
2007 GPS Solutions  
A methodology is described here that uses existing networks of continuously-operating GPS receivers to measure soil moisture fluctuations.  ...  After describing this technique, multipath reflection amplitudes at a GPS site in Tashkent, Uzbekistan are compared to estimates of soil moisture from the Noah land surface model.  ...  It is difficult to isolate the effects of multipath in GPS carrier phase observable because of the need to model orbits, atmospheric delays, clocks, and positions in a least squares analysis.  ... 
doi:10.1007/s10291-007-0076-6 fatcat:m4wo6z5cibgghfq6tj6hxolwmu
« Previous Showing results 1 — 15 out of 380 results