FMCW Radar Phase-Processing for Automotive Application

An unmanned high-speed vehicle requires a high resolution control unit to decide whether the vehicle should break or steer. This paper describes the utilization of a Frequency Modulated Continous Wave (FMCW) radar to detect the distance and angular position of the target relative to the moving vehicle. These informations are calculated from some numbers of data obtained from a radar system that is mounted on the moving vehicle. To obtain a high angular resolution, a phase-processing approach is introduced by extracting the constant phase information from the radar FMCW beat signal. It is found that a very high angular resolution can be obtained by processing the phase information, independent from the change of relative velocity between the radar and the target. However, this method requires a very stable radar system with high phase resolution and accuracy

Surface Melting Drives Fluctuations in Airborne Radar Penetration in West Central Greenland

Greenland Ice Sheet surface melting has increased since the 1990s, affecting the rheology and scattering properties of the near‐surface firn. We combine firn cores and modeled firn densities with 7 years of CryoVEx airborne Ku‐band (13.5 GHz) radar profiles to quantify the impact of melting on microwave radar penetration in West Central Greenland. Although annual layers are present in the Ku‐band radar profiles to depths up to 15 m below the ice sheet surface, fluctuations in summer melting strongly affect the degree of radar penetration. The extreme melting in 2012, for example, caused an abrupt 6.2 ± 2.4 m decrease in Ku‐band radar penetration. Nevertheless, retracking the radar echoes mitigates this effect, producing surface heights that agree to within 13.9 cm of coincident airborne laser measurements. We also examine 2 years of Ka‐band (34.5 GHz) airborne radar data and show that the degree of penetration is half that of coincident Ku‐band

NetCDF files containing raster layers of the Airborne SnowSAR observations land cover (LC), elevation (DEM), canopy cover (CC), tree height (TH) and stem volume (VOL) over the Finnish sites Sodankylä and Saariselkä in march 2011 and winter 2011-2012

NetCDF files containing raster layers of the Airborne SnowSAR observations, land cover (LC), elevation (DEM), canopy cover (CC), tree height (TH) and stem volume (VOL) over the Finnish sites; Sodankylä and Saariselkä. The Airborne SnowSAR observations include the mean and the standard deviation of the X- and Ku-band backscatter (sigma nought) in VV- and VH-polarization, as well as the incidence angle in 10 m pixel size. The airborne data was collected in winter 2011-2012, except mission00 from Sodankylä, which was collected in March 2011

NetCDF files containing raster layers of the Airborne SnowSAR observations, land cover (SCM) and elevation (DEM) over the over the Canadian ”TVC” site in winter 2012-2013

NetCDF files containing raster layers of the Airborne SnowSAR observations, land cover (VEG) and elevation (DEM) over the Canadian ”TVC” site. The Airborne SnowSAR observations include the mean and the standard deviation of the X- and Ku-band backscatter (sigma nought) in VV- and VH-polarization, as well as the incidence angle in 10 m pixel size. The TVC airborne data was collected in winter 2012-2013

NetCDF files containing raster layers of the Airborne SnowSAR observations, land cover (SCM) and elevation (DEM) over the Austrian ”AlpSAR” sites (Leutasch, Mittelbergferner and Rotmoos) in winter 2012-2013

NetCDF files containing raster layers of the Airborne SnowSAR observations, land cover (SCM) and elevation (DEM) over the Austrian ”AlpSAR” sites; Leutasch, Mittelbergferner and Rotmoos. The Airborne SnowSAR observations include the mean and the standard deviation of the X- and Ku-band backscatter (sigma nought) in VV- and VH-polarization, as well as the incidence angle in 10 m pixel size. The AlpSAR airborne data was collected in winter 2012-201

The SARSense campaign: air- and space-borne C- and L-band SAR for the analysis of soil and plant parameters in agriculture

With the upcoming L-band Synthetic Aperture Radar (SAR) satellite mission Radar Observing System for Europe L-band SAR (ROSE-L) and its integration into existing C-band satellite missions such as Sentinel-1, multi-frequency SAR observations with high temporal and spatial resolution will become available. The SARSense campaign was conducted between June and August 2019 to investigate the potential for estimating soil and plant parameters at the agricultural test site in Selhausen (Germany). It included C- and L-band air- and space-borne observations accompanied by extensive in situ soil and plant sampling as well as unmanned aerial system (UAS) based multispectral and thermal infrared measurements. In this regard, we introduce a new publicly available SAR data set and present the first analysis of C- and L-band co- and cross-polarized backscattering signals regarding their sensitivity to soil and plant parameters. Results indicate that a multi-frequency approach is relevant to disentangle soil and plant contributions to the SAR signal and to identify specific scattering mechanisms associated with the characteristics of different crop type, especially for root crops and cereals

THE TOMOSENSE EXPERIMENT: MONO- AND BISTATIC SAR TOMOGRAPHY OF FORESTED AREAS AT P-, L-, AND C-BAND

The TomoSense experiment comprises campaign and research activities in support of future Synthetic Aperture Radar (SAR) mission concepts at P-, L-, and C-band by the European Space Agency (ESA). The research is intended to provide a quantitative basis for the evaluation of single-pass interferometry over temperate forests at L- and C-band and investigate potential synergies between C-band convoy mission concepts and future P- and L-band missions. SAR acquisitions include P- L-, and C-band data acquired at the Eifel National Park in Germany by flying approximately 25 trajectories to provide tomographic imaging capabilities. L- and C-band data were acquired by simultaneously flying two aircraft to gather bistatic data with varying interferometric baselines. Field activities include forest census (dbh, tree height and species) at 80 plots and Terrestrial Laser Scanning (TLS). The dataset is complemented by small-footprint Airborne Lidar Scanning (ALS) and derived products. Preliminary results are here shown relative to polarimetric tomography at P-band and L-band imaging

Surface melting drives fluctuations in airborne radar penetration in West Central Greenland

Greenland Ice Sheet surface melting has increased since the 1990s, affecting the rheology and scattering properties of the near‐surface firn. We combine firn cores and modeled firn densities with 7 years of CryoVEx airborne Ku‐band (13.5 GHz) radar profiles to quantify the impact of melting on microwave radar penetration in West Central Greenland. Although annual layers are present in the Ku‐band radar profiles to depths up to 15 m below the ice sheet surface, fluctuations in summer melting strongly affect the degree of radar penetration. The extreme melting in 2012, for example, caused an abrupt 6.2 ± 2.4 m decrease in Ku‐band radar penetration. Nevertheless, retracking the radar echoes mitigates this effect, producing surface heights that agree to within 13.9 cm of coincident airborne laser measurements. We also examine 2 years of Ka‐band (34.5 GHz) airborne radar data and show that the degree of penetration is half that of coincident Ku‐band

TomoSense : A unique 3D dataset over temperate forest combining multi-frequency mono- and bi-static tomographic SAR with terrestrial, UAV and airborne lidar, and in-situ forest census

The TomoSense experiment was funded by the European Space Agency (ESA) to support research on remote sensing of forested areas by means of Synthetic Aperture Radar (SAR) data, with a special focus on the use of tomographic SAR (TomoSAR) to retrieve information about the vertical structure of the vegetation at different frequency bands. The illuminated scene is the temperate forest at the Eifel National Park, North-West Germany. Dominant species are beech and spruce trees. Forest height ranges roughly from 10 to 30 m, with peaks up to over 40 m. Forest Above Ground Biomass (AGB) ranges from 20 to 300 Mg/ha, with peaks up to over 400 Mg/ha. SAR data include P-, L-, and C-band surveys acquired by flying up to 30 trajectories in two headings to provide tomographic imaging capabilities. L- and C-band data were acquired by simultaneously flying two aircraft to gather bistatic data along different trajectories. The SAR dataset is complemented by 3D structural canopy measurements made via terrestrial laser scanning (TLS), Unoccupied Aerial Vehicle lidar (UAV-L) and airborne laser scanning (ALS), and in-situ forest census. This unique combination of SAR tomographic and multi-scale lidar data allows for direct comparison of canopy structural metrics across wavelength and scale, including vertical profiles of canopy wood and foliage density, and per-tree and plot-level above ground biomass (AGB). The resulting TomoSense data-set is free and openly available at ESA for any research purpose. The data-set includes ALS-derived maps of forest height and AGB, forest parameters at the level of single trees, TLS raw data, and plot-average TLS vertical profiles. The provided SAR data are coregistered, phase calibrated, and ground steered, to enable a direct implementation of any kind of interferometric or tomographic processing without having to deal with the subtleties of airborne SAR processing. Moreover, the data-base comprises SAR tomographic cubes representing forest scattering in 3D both in Radar and geographical coordinates, intended for use by non-Radar experts. For its unique features and completeness, the TomoSense data-set is intended to serve as an important basis for future research on microwave scattering from forested areas in the context of future Earth Observation missions