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Geometric Distortion Correction of Spaceborne GNSS-R Delay-Doppler Map Using Reconstruction
摘要： For spaceborne Global Navigation Satellite System-Reflectometry (GNSS-R), the delay difference of direct and reflected GNSS signals among successive snapshots changes rapidly because of the high dynamics of low earth orbital and GNSS satellites. This change has to be compensated to avoid the distortion of incoherently averaged delay-Doppler map (DDM). The method to refresh the correlation window on each coherent integration time period may require too many instrument resources or too much data to be uploaded from the ground station. This letter proposes a new postprocessing approach based on the motion degradation model of DDM and the reconstruction to replace real-time compensation. Raw sampled data from UK TechDemoSat-1 are used to verify the availability of proposed approach. The results show that after reconstruction for the distorted DDM, the DDM accuracies relative to that compensated in real time are significantly improved.
关键词： Global Navigation Satellite System-Reflectometry (GNSS-R),reconstruction,Distorted delay-Doppler map (DDM)
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Relationship Between Bistatic Radar Scattering Cross Sections and GPS Reflectometry Delay-Doppler Maps Over Vegetated Land in Support of Soil Moisture Retrieval
摘要： This paper presents the application of a coherent bistatic radar scattering model from vegetated terrains and the extension of the model to circularly polarized incident wave cases for GNSS signals. It will then present an analysis relating the bistatic scattering Radar Cross Sections (RCS) of vegetated land cover to the customary Delay Doppler Maps (DDMs) resulting, e.g., from GNSS reflectometry (GNSS-R) observations. This step is key in being able to use GNSS-R data in soil moisture retrieval algorithms. While some analyses exist for this purpose for scattering from sea surface, such analysis has not been carried out specifically for vegetated land surface. The proposed model and methods are envisioned to be applied to the airborne GNSS Reflectometer Instrument for Bistatic SAR (GRIBSAR) project currently under development, as well as to the CYGNSS mission.
关键词： GRIBSAR,Coherent bistatic radar scattering model,GNSS-R,RCS,Delay Doppler Map
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Analysis of CYGNSS Data for Soil Moisture Applications
摘要： An analysis of CYGNSS data is presented, with the objective of assessing the potentials of these data for land applications. The GPS-Reflections over land acquired by the CYGNSS observatories are exploited to detect properties of the land soil moisture. A land reflectivity observable, derived from CYGNSS Delay/Doppler Maps, is computed using a calibration approach suitable for land reflections. The sensitivity of the reflectivity observable to the soil moisture parameter is investigated through a comparison with soil moisture data from the SMAP satellite. Some preliminary results on the correlation between the CYGNSS reflectivity and the SMAP soil moisture are presented. This work is being conducted within the framework of the European Space Agency Project “Potential of Spaceborne GNSS-R for Land Applications”.
关键词： Delay-Doppler Map,soil moisture,GPS-Reflectometry
更新于2025-09-10 09:29:36