Untangling the Incoherent and Coherent Scattering Components in GNSS-R and Novel Applications
Open Access
- 9 April 2020
- journal article
- research article
- Published by MDPI AG in Remote Sensing
- Vol. 12 (7), 1208
- https://doi.org/10.3390/rs12071208
Abstract
As opposed to monostatic radars where incoherent backscattering dominates, in bistatic radars, such as Global Navigation Satellite Systems Reflectometry (GNSS-R), the forward scattered signals exhibit both an incoherent and a coherent component. Current models assume that either one or the other are dominant, and the calibration and geophysical parameter retrieval (e.g., wind speed, soil moisture, etc.) are developed accordingly. Even the presence of the coherent component of a GNSS reflected signal itself has been a matter of discussion in the last years. In this work, a method developed to separate the leakage of the direct signal in the reflected one is applied to a data set of GNSS-R signals collected over the ocean by the Microwave Interferometer Reflectometer (MIR) instrument, an airborne dual-band (L1/E1 and L5/E5a), multi-constellation (GPS and Galileo) GNSS-R instrument with two 19-elements antenna arrays with 4 beam-steered each. The presented results demonstrate the feasibility of the proposed technique to untangle the coherent and incoherent components from the total power waveform in GNSS reflected signals. This technique allows the processing of these components separately, which increases the calibration accuracy (as today both are mixed and processed together), allowing higher resolution applications since the spatial resolution of the coherent component is determined by the size of the first Fresnel zone (300–500 meters from a LEO satellite), and not by the size of the glistening zone (25 km from a LEO satellite). The identification of the coherent component enhances also the location of the specular reflection point by determining the peak maximum from this coherent component rather than the point of maximum derivative of the incoherent one, which is normally noisy and it is blurred by all the glistening zone contributions.This publication has 23 references indexed in Scilit:
- A CYGNSS‐Based Algorithm for the Detection of Inland WaterbodiesGeophysical Research Letters, 2019
- Spatial Resolution in GNSS-R Under Coherent ScatteringIEEE Geoscience and Remote Sensing Letters, 2019
- Satellite Cross-Talk Impact Analysis in Airborne Interferometric Global Navigation Satellite System-Reflectometry with the Microwave Interferometric ReflectometerRemote Sensing, 2019
- The Transition From Weak to Strong Diffuse Radar Bistatic Scattering From Rough Ocean SurfaceIEEE Transactions on Antennas and Propagation, 2017
- Sea Ice Detection Using U.K. TDS-1 GNSS-R DataIEEE Transactions on Geoscience and Remote Sensing, 2017
- Unified GNSS-R formulation including coherent and incoherent scattering componentsPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2016
- First Polarimetric GNSS-R Measurements from a Stratospheric Flight over Boreal ForestsRemote Sensing, 2015
- Retrieval of Significant Wave Height and Mean Sea Surface Level Using the GNSS-R Interference Pattern Technique: Results From a Three-Month Field CampaignIEEE Transactions on Geoscience and Remote Sensing, 2014
- The microwave interferometric reflectometer. Part II: Back-end and processor descriptionsPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2014
- Land Geophysical Parameters Retrieval Using the Interference Pattern GNSS-R TechniqueIEEE Transactions on Geoscience and Remote Sensing, 2010