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The demonstration of the feasibility of navigation signals signals for remote sensing has lead to a significant increase of new GNSS-R instruments in the recent years. Despite of the type instrument, the observables are based on the cross-correlations of the received GNSS signals. Most of these instruments combine the signals received by multiple chains, in such a way that they need a proper calibration...
Radio-Frequency Interference (RFI) is a growing problem for applications based on the Global Navigation Satellite Systems (GNSS), including Earth observation using GNSS — Reflectometry (GNSS-R). Nowadays, many efforts are being concentrated to develop RFI signal detectors with high sensitivity, which can help to control the proliferation of RFI generators or jammers. This work aims at designing and...
This work reviews and analyses potentially relevant technologies to ensure that the gaps and stakeholder needs for sea ice products are covered. Each variable related to sea ice that presenting gaps using the European EO infrastructure on the horizon (2020–2030) is revised according the stakeholder requirements, together with the feasibility of deploying available technologies on small satellites...
Radio-Frequency Interference (RFI) is a well-known problem for Microwave Radiometers (MWR). A number of RFI mitigation techniques have been studied to deal with RFI from the receiver's side. In this study, a comparison in terms of performance among several real-time time-frequency RFI mitigation techniques is presented. Time-frequency techniques are of high importance because the vast majority of...
Reflectometry using Global Navigation Satellite System's signals of opportunity (GNSS-R) was originally conceived in the early 90s for mesoscale altimetry, and since then, many studies have shown its applicability to other remote sensing applications. In 2002, the Remote Sensing Lab at the Universitat Politècnica de Catalunya started working in Global Navigation Satellite Reflectometry (GNSS-R) to...
This work presents the PAU instrument aboard the satellite INTA MicroSAT-1. The PAU instrument is a combination of a Radiometer and a GNSS Reflectometer designed to study the relationship GNSS-R observables (Delay Doppler Maps) and the L-Band brightness temperature measurements to improve the Sea Surface Salinity (SSS) retrievals. This work describes an airborne experiment conducted to preliminary...
This paper presents calibration and the radiometric performance of the Passive Advanced Unit Synthetic Aperture (PAU-SA) in order to verify the instrument's characterization.
This work presents the flight model of a PAU version to be flown in INTA's (Instituto Nacional de Técnicas Aeroespaciales, Spanish Aerospace Center) MicroSat-1 and the tests performed. PAU is a hybrid GNSS-Reflectometer / Microwave Radiometer developed to assess the impact of the sea state on the L-band brightness temperatures and on the GNSS-R observables (the Delay Doppler Maps or DDMs). The DDMs...
This paper presents the Passive Advanced Unit Synthetic Aperture instrument (PAU-SA), and some of the first experimental results: the use of pseudo-random noise signals for a complete baseline calibration and receivers' frequency response characterization, the use of a Kalman filter to better estimate the receivers' phase between internal calibrations, the imaging of an artificial point source at...
In recent decades, atmospheric scientists have been interested in measuring thermodynamic variables such as tropospheric water vapor and temperature with increasing temporal and spatial resolution due to their importance on the climate modeling. For this purpose, microwave radiometers have been used to measure columnar integrated water vapor. The radiative transfer equation (RTE) has been used to...
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