Untangling the Incoherent and Coherent Scattering Components in GNSS-R and Novel Applications
1
CommSensLab—UPC, Universitat Politècnica de Catalunya—BarcelonaTech, and IEEC/CTE-UPC, 08034 Barcelona, Spain
2
Department of Civil Engineering, Monash University, Clayton, VIC 3800, Australia
3
Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
*
Authors to whom correspondence should be addressed.
Remote Sens. 2020, 12(7), 1208; https://doi.org/10.3390/rs12071208
Received: 26 February 2020 / Revised: 2 April 2020 / Accepted: 4 April 2020 / Published: 9 April 2020
(This article belongs to the Special Issue Applications of GNSS Reflectometry for Earth Observation)
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.
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Keywords:
GNSS-R; sea; coherent scattering; incoherent scattering
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MDPI and ACS Style
Munoz-Martin, J.F.; Onrubia, R.; Pascual, D.; Park, H.; Camps, A.; Rüdiger, C.; Walker, J.; Monerris, A. Untangling the Incoherent and Coherent Scattering Components in GNSS-R and Novel Applications. Remote Sens. 2020, 12, 1208.
AMA Style
Munoz-Martin JF, Onrubia R, Pascual D, Park H, Camps A, Rüdiger C, Walker J, Monerris A. Untangling the Incoherent and Coherent Scattering Components in GNSS-R and Novel Applications. Remote Sensing. 2020; 12(7):1208.
Chicago/Turabian StyleMunoz-Martin, Joan F.; Onrubia, Raul; Pascual, Daniel; Park, Hyuk; Camps, Adriano; Rüdiger, Christoph; Walker, Jeffrey; Monerris, Alessandra. 2020. "Untangling the Incoherent and Coherent Scattering Components in GNSS-R and Novel Applications" Remote Sens. 12, no. 7: 1208.
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