Alfredo Renga | Università degli Studi di Napoli "Federico II" (original) (raw)
Papers by Alfredo Renga
2014 IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems Proceedings, 2014
The ionosphere is commonly divided into the portion below (bottomside) and above (topside) the re... more The ionosphere is commonly divided into the portion below (bottomside) and above (topside) the region at which peak values of electron density occur. Topside ionospheric modeling is a challenging problem because of the limited data available. Indeed, the more intense peak ionization region, or bottomside ionosphere, dominates the effects observable from ground stations. High-altitude ionosondes, such as sounding rockets, have been traditionally used for direct sounding only of the higher ionospheric layers. Nowadays, signals of opportunity exist for sounding the ionosphere with no dedicated ionosondes. With the continuous deployment of GPS receivers on board spacecraft for positioning, indirect sounding of the topside ionosphere using navigation signals can be performed. This paper reviews geometric-based models allowing to infer the total electron content of the topside ionosphere from spacecraft GPS measurements.
International Journal of Aerospace Engineering, 2015
The paper investigates different solutions for ionospheric delay handling in high accuracy long b... more The paper investigates different solutions for ionospheric delay handling in high accuracy long baseline relative positioning by Carrier-Phase Differential GPS (CDGPS). Standard literature approaches are reviewed and the relevant limitations are discussed. Hence, a completely ionosphere-free approach is proposed, in which the differential ionospheric delays are cancelled out by combination of dual frequency GPS measurements. The performance of this approach is quantified over real-world spaceborne GPS data made available by the Gravity Recovery and Climate Experiment (GRACE) mission and compared to the standard solution.
Remote Sensing
The synergic utilization of data from different sources, either ground-based or spaceborne, can l... more The synergic utilization of data from different sources, either ground-based or spaceborne, can lead to effective monitoring of maritime activities. To this end, the integration of synthetic aperture radar (SAR) images with data reported by the automatic identification system (AIS) is of high interest. Accurate matching of ships detected in SAR images with AIS data requires compensation of the azimuth offset, which depends on the ship’s velocity. The existing procedures interpolate the route information gathered by AIS to estimate the ship’s velocity at the epoch of the SAR data, to remove the offset. Matching accuracy is limited by interpolation errors and AIS route information unavailability or uncertainties. This paper proposes the use of SAR-based ship velocity estimations to improve the integration of AIS and SAR data. A case study has been analyzed, in which the method has been tested on TerraSAR-X images collected over the Gulf of Naples, Italy. Presented results show that th...
2010 IEEE International Geoscience and Remote Sensing Symposium, 2010
Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bista... more Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bistatic Synthetic Aperture Radar (SAR) is presented. The innovative bistatic configuration builds on spaceborne radar transmitters and airborne receivers, the latter mounted in a forward-looking geometry. Such approach, impossible or extremely demanding with a monostatic approach, allows one to achieve dual information with two different radar working modes: imaging capability can be in fact coupled with the ...
IEEE transactions on geoscience and remote …, Jan 1, 2011
Résumé/Abstract This paper analyzes the spatial resolution of bistatic synthetic aperture radar (... more Résumé/Abstract This paper analyzes the spatial resolution of bistatic synthetic aperture radar (SAR) in general hybrid configurations, such as air-and spaceborne systems moving along independent trajectories. The gradient method is utilized to point out the effects of ...
& Proceedings 저널· 프로시딩즈| 기술보고서| …
This paper deals with the GPS-based relative navigation of LEO formations. Specifically, we consi... more This paper deals with the GPS-based relative navigation of LEO formations. Specifically, we consider applications characterized by two co-flying satellites with a large and highly variable separation, which are relevant to next generation monostatic/bistatic Synthetic Aperture ...
In armonia con gli obiettivi strategici definiti nel Piano Aerospaziale Nazionale (PASN), e nell&... more In armonia con gli obiettivi strategici definiti nel Piano Aerospaziale Nazionale (PASN), e nell'ambito dell'esplorazione del sistema solare, l'ASI intende elaborare una Vision per l'esplorazione della Luna a partire dal 2011, tale Vision, denominata “Italian Vision for ...
Bistatic Synthetic Aperture Radar is defined when antennas for reception and transmission are phy... more Bistatic Synthetic Aperture Radar is defined when antennas for reception and transmission are physically separated. Such a spatial separation allows bistatic SAR to operate in different geometric and functional configurations, thus being able to achieve a vast ...
… and Remote Sensing …, Jan 1, 2010
Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bista... more Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bistatic Synthetic Aperture Radar (SAR) is presented. The innovative bistatic configuration builds on spaceborne radar transmitters and airborne receivers, the latter mounted in a forward-looking geometry. Such approach, impossible or extremely demanding with a monostatic approach, allows one to achieve dual information with two different radar working modes: imaging capability can be in fact coupled with the ...
Sensors, Jan 1, 2009
During the last decade a methodology for the reconstruction of surface relief by Synthetic Apertu... more During the last decade a methodology for the reconstruction of surface relief by Synthetic Aperture Radar (SAR) measurements -SAR interferometry -has become a standard. Different techniques developed before, such as stereo-radargrammetry, have been experienced from space only in very limiting geometries and time series, and, hence, branded as less accurate. However, novel formation flying configurations achievable by modern spacecraft allow fulfillment of SAR missions able to produce pairs of monostatic-bistatic images gathered simultaneously, with programmed looking angles. Hence it is possible to achieve large antenna separations, adequate for exploiting to the utmost the stereoscopic effect, and to make negligible time decorrelation, a strong liming factor for repeat-pass stereo-radargrammetric techniques. This paper reports on design of a monostatic-bistatic mission, in terms of orbit and pointing geometry, and taking into account present generation SAR and technology for accurate relative navigation. Performances of different methods for monostatic-bistatic stereo-radargrammetry are then evaluated, showing the possibility to determine the local surface relief with a metric accuracy over a wide range of Earth latitudes.
Synthetic Aperture Radar (EUSAR), 2010 …, Jan 1, 2010
Abstract Recently important experimentations were conducted on the use of space-airborne bistatic... more Abstract Recently important experimentations were conducted on the use of space-airborne bistatic SAR. All the performed experiments relied on side-looking geometry both for the transmitter and the receiver, with platforms moving on parallel tracks, thus reducing ...
Small Satellite Missions for Earth …, Jan 1, 2010
... Department of Aerospace Engineering, University of Naples Federico II, P.le Tecchio 80, 801... more ... Department of Aerospace Engineering, University of Naples Federico II, P.le Tecchio 80, 80125, Naples, Italy e-mail: michele.grassi@unina.it ... Since this Toolbox is developed mainly for Earth-based GPS receivers, to adapt it to LEO receivers it was necessary to introduce a ...
… , 2012. EUSAR. 9th …, Jan 1, 2012
ABSTRACT An analysis of ship detection algorithms is presented for potential application in a fut... more ABSTRACT An analysis of ship detection algorithms is presented for potential application in a future ship detection facility which would make use of SAR products aided by AIS information. A validation of Wackrman's algorithm is also reported based on images of the Gulf of Naples gathered by COSMO/SkyMed. It is shown that, although successful in most cases, different approaches are required to discriminate between ships and image artefacts.
Aerospace and Electronic Systems, IEEE …, Jan 1, 2010
Abstract Starting from the reborn international interest in lunar exploration and the widely docu... more Abstract Starting from the reborn international interest in lunar exploration and the widely documented need for hyper-accurate measurements of Earth crustal dynamics, at a high revisit frequency and on a global scale, the idea of a Moon-based interferometric synthetic ...
Proceedings of SPIE, Jan 1, 2011
ABSTRACT Maritime surveillance problems are drawing the attention of multiple institutional actor... more ABSTRACT Maritime surveillance problems are drawing the attention of multiple institutional actors. National and international security agencies are interested in matters like maritime traffic security, maritime pollution control, monitoring migration flows and detection of illegal fishing activities. Satellite imaging is a good way to identify ships but, characterized by large swaths, it is likely that the imaged scenes contain a large number of ships, with the vast majority, hopefully, performing legal activities. Therefore, the imaging system needs a supporting system which identifies legal ships and limits the number of potential alarms to be further monitored by patrol boats or aircrafts. In this framework, spaceborne Synthetic Aperture Radar (SAR) sensors, terrestrial AIS and the ongoing satellite AIS systems can represent a great potential synergy for maritime security. Starting from this idea the paper develops different designs for an AIS constellation able to reduce the time lag between SAR image and AIS data acquisition. An analysis of SAR-based ship detection algorithms is also reported and candidate algorithms identified.
Proceedings of SPIE, Jan 1, 2009
Performance analysis of Bistatic Synthetic Aperture Radar (SAR) characterized by arbitrary geomet... more Performance analysis of Bistatic Synthetic Aperture Radar (SAR) characterized by arbitrary geometric configurations is usually complex and time-consuming since system impulse response has to be evaluated by bistatic SAR processing. This approach does not allow derivation of general equations regulating the behaviour of image resolutions with varying the observation geometry. It is well known that for an arbitrary configuration of bistatic SAR there are not perpendicular range and azimuth directions, but the capability to produce an image is not prevented as it depends only on the possibility to generate image pixels from time delay and Doppler measurements. However, even if separately range and Doppler resolutions are good, bistatic SAR geometries can exist in which imaging capabilities are very poor when range and Doppler directions become locally parallel. The present paper aims to derive analytical tools for calculating the geometric resolutions of arbitrary configuration of bistatic SAR. The method has been applied to a hybrid bistatic Synthetic Aperture Radar formed by a spaceborne illuminator and a receiving-only airborne forward-looking Synthetic Aperture Radar (F-SAR). It can take advantage of the spaceborne illuminator to dodge the limitations of monostatic FSAR. Basic modeling and best illumination conditions have been detailed in the paper.
Synthetic Aperture Radar (EUSAR), 2008 …, Jan 1, 2008
... Antonio, Moccia, University of Naples, Italy Alfredo, Renga, University of Naples, Italy ... ... more ... Antonio, Moccia, University of Naples, Italy Alfredo, Renga, University of Naples, Italy ... [5] PA Rosen, S. Hensley, IR Joughin, FK Li, SN Madsen, E. Rodriguez, and RM Gold-stein, Synthetic Aperture Radar Interfero-metry, Proceedings of the IEEE, 88, 3, 333-382, 2000. ...
Advances in Space Research, Jan 1, 2011
GPS relative navigation filters could benefit notably from an accurate modeling of the ionospheri... more GPS relative navigation filters could benefit notably from an accurate modeling of the ionospheric delays, especially over large baselines (>100 km) where double difference delays can be higher than several carrier wavelengths. This paper analyzes the capability of ionospheric path delay models proposed for spaceborne GPS receivers in predicting both zero-difference and double difference ionospheric delays. We specifically refer to relatively simple ionospheric models, which are suitable for real-time filtering schemes. Specifically, two ionospheric delay models are evaluated, one assuming an isotropic electron density and the other considering the effect on the electron density of the Sun aspect angle. The prediction capability of these models is investigated by comparing predicted ionospheric delays with measured ones on real flight data from the Gravity Recovery and Climate Experiment mission, in which two satellites fly separated of more than 200 km. Results demonstrate that both models exhibit a correlation in the excess of 80% between predicted and measured double-difference ionospheric delays. Despite its higher simplicity, the isotropic model performs better than the model including the Sun effect, being able to predict double differenced delays with accuracy smaller than the carrier wavelength in most cases. The model is thus fit for supporting integer ambiguity fixing in real-time filters for relative navigation over large baselines. Concerning zerodifference ionospheric delays, results demonstrate that delays predicted by the isotropic model are highly correlated (around 90%) with those estimated using GPS measurements. However, the difference between predicted and measured delays has a root mean square error in the excess of 30 cm. Thus, the zero-difference ionospheric delays model is not likely to be an alternative to methods exploiting carrier-phase observables for cancelling out the ionosphere contribution in single-frequency absolute navigation filters.
Geoscience and Remote Sensing, IEEE …, Jan 1, 2009
This paper aims to investigate the performance of stereoradargrammetric methods applied to spaceb... more This paper aims to investigate the performance of stereoradargrammetric methods applied to spaceborne monostatic-bistatic synthetic aperture radar (SAR) data for digital elevation model (DEM) generation. Stereoradargrammetric techniques for robust DEM generation were successfully experienced on monostatic repeat-pass SIR-A, SIR-B, SIR-C/X-SAR, ERS1/2, JERS-1, and Radarsat data. However, novel configurations achievable by modern spacecraft flying in formation will allow for the attainment of very large baselines between the antennas in a single-pass bistatic geometry so that the height determination accuracy can benefit from both stereo effect and simultaneous acquisition. Five models for relief reconstruction by monostatic-bistatic SAR stereoradargrammetry are presented, and an error budget is assessed for each of them. Results of the sensitivity analysis exhibit metric accuracy, and therefore, the technique could be applied for height reconstruction as a methodology complementary to SAR interferometry.
2014 IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems Proceedings, 2014
The ionosphere is commonly divided into the portion below (bottomside) and above (topside) the re... more The ionosphere is commonly divided into the portion below (bottomside) and above (topside) the region at which peak values of electron density occur. Topside ionospheric modeling is a challenging problem because of the limited data available. Indeed, the more intense peak ionization region, or bottomside ionosphere, dominates the effects observable from ground stations. High-altitude ionosondes, such as sounding rockets, have been traditionally used for direct sounding only of the higher ionospheric layers. Nowadays, signals of opportunity exist for sounding the ionosphere with no dedicated ionosondes. With the continuous deployment of GPS receivers on board spacecraft for positioning, indirect sounding of the topside ionosphere using navigation signals can be performed. This paper reviews geometric-based models allowing to infer the total electron content of the topside ionosphere from spacecraft GPS measurements.
International Journal of Aerospace Engineering, 2015
The paper investigates different solutions for ionospheric delay handling in high accuracy long b... more The paper investigates different solutions for ionospheric delay handling in high accuracy long baseline relative positioning by Carrier-Phase Differential GPS (CDGPS). Standard literature approaches are reviewed and the relevant limitations are discussed. Hence, a completely ionosphere-free approach is proposed, in which the differential ionospheric delays are cancelled out by combination of dual frequency GPS measurements. The performance of this approach is quantified over real-world spaceborne GPS data made available by the Gravity Recovery and Climate Experiment (GRACE) mission and compared to the standard solution.
Remote Sensing
The synergic utilization of data from different sources, either ground-based or spaceborne, can l... more The synergic utilization of data from different sources, either ground-based or spaceborne, can lead to effective monitoring of maritime activities. To this end, the integration of synthetic aperture radar (SAR) images with data reported by the automatic identification system (AIS) is of high interest. Accurate matching of ships detected in SAR images with AIS data requires compensation of the azimuth offset, which depends on the ship’s velocity. The existing procedures interpolate the route information gathered by AIS to estimate the ship’s velocity at the epoch of the SAR data, to remove the offset. Matching accuracy is limited by interpolation errors and AIS route information unavailability or uncertainties. This paper proposes the use of SAR-based ship velocity estimations to improve the integration of AIS and SAR data. A case study has been analyzed, in which the method has been tested on TerraSAR-X images collected over the Gulf of Naples, Italy. Presented results show that th...
2010 IEEE International Geoscience and Remote Sensing Symposium, 2010
Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bista... more Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bistatic Synthetic Aperture Radar (SAR) is presented. The innovative bistatic configuration builds on spaceborne radar transmitters and airborne receivers, the latter mounted in a forward-looking geometry. Such approach, impossible or extremely demanding with a monostatic approach, allows one to achieve dual information with two different radar working modes: imaging capability can be in fact coupled with the ...
IEEE transactions on geoscience and remote …, Jan 1, 2011
Résumé/Abstract This paper analyzes the spatial resolution of bistatic synthetic aperture radar (... more Résumé/Abstract This paper analyzes the spatial resolution of bistatic synthetic aperture radar (SAR) in general hybrid configurations, such as air-and spaceborne systems moving along independent trajectories. The gradient method is utilized to point out the effects of ...
& Proceedings 저널· 프로시딩즈| 기술보고서| …
This paper deals with the GPS-based relative navigation of LEO formations. Specifically, we consi... more This paper deals with the GPS-based relative navigation of LEO formations. Specifically, we consider applications characterized by two co-flying satellites with a large and highly variable separation, which are relevant to next generation monostatic/bistatic Synthetic Aperture ...
In armonia con gli obiettivi strategici definiti nel Piano Aerospaziale Nazionale (PASN), e nell&... more In armonia con gli obiettivi strategici definiti nel Piano Aerospaziale Nazionale (PASN), e nell'ambito dell'esplorazione del sistema solare, l'ASI intende elaborare una Vision per l'esplorazione della Luna a partire dal 2011, tale Vision, denominata “Italian Vision for ...
Bistatic Synthetic Aperture Radar is defined when antennas for reception and transmission are phy... more Bistatic Synthetic Aperture Radar is defined when antennas for reception and transmission are physically separated. Such a spatial separation allows bistatic SAR to operate in different geometric and functional configurations, thus being able to achieve a vast ...
… and Remote Sensing …, Jan 1, 2010
Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bista... more Abstract The study of a novel navigation system for Unmanned Airborne System (UAS) based on bistatic Synthetic Aperture Radar (SAR) is presented. The innovative bistatic configuration builds on spaceborne radar transmitters and airborne receivers, the latter mounted in a forward-looking geometry. Such approach, impossible or extremely demanding with a monostatic approach, allows one to achieve dual information with two different radar working modes: imaging capability can be in fact coupled with the ...
Sensors, Jan 1, 2009
During the last decade a methodology for the reconstruction of surface relief by Synthetic Apertu... more During the last decade a methodology for the reconstruction of surface relief by Synthetic Aperture Radar (SAR) measurements -SAR interferometry -has become a standard. Different techniques developed before, such as stereo-radargrammetry, have been experienced from space only in very limiting geometries and time series, and, hence, branded as less accurate. However, novel formation flying configurations achievable by modern spacecraft allow fulfillment of SAR missions able to produce pairs of monostatic-bistatic images gathered simultaneously, with programmed looking angles. Hence it is possible to achieve large antenna separations, adequate for exploiting to the utmost the stereoscopic effect, and to make negligible time decorrelation, a strong liming factor for repeat-pass stereo-radargrammetric techniques. This paper reports on design of a monostatic-bistatic mission, in terms of orbit and pointing geometry, and taking into account present generation SAR and technology for accurate relative navigation. Performances of different methods for monostatic-bistatic stereo-radargrammetry are then evaluated, showing the possibility to determine the local surface relief with a metric accuracy over a wide range of Earth latitudes.
Synthetic Aperture Radar (EUSAR), 2010 …, Jan 1, 2010
Abstract Recently important experimentations were conducted on the use of space-airborne bistatic... more Abstract Recently important experimentations were conducted on the use of space-airborne bistatic SAR. All the performed experiments relied on side-looking geometry both for the transmitter and the receiver, with platforms moving on parallel tracks, thus reducing ...
Small Satellite Missions for Earth …, Jan 1, 2010
... Department of Aerospace Engineering, University of Naples Federico II, P.le Tecchio 80, 801... more ... Department of Aerospace Engineering, University of Naples Federico II, P.le Tecchio 80, 80125, Naples, Italy e-mail: michele.grassi@unina.it ... Since this Toolbox is developed mainly for Earth-based GPS receivers, to adapt it to LEO receivers it was necessary to introduce a ...
… , 2012. EUSAR. 9th …, Jan 1, 2012
ABSTRACT An analysis of ship detection algorithms is presented for potential application in a fut... more ABSTRACT An analysis of ship detection algorithms is presented for potential application in a future ship detection facility which would make use of SAR products aided by AIS information. A validation of Wackrman's algorithm is also reported based on images of the Gulf of Naples gathered by COSMO/SkyMed. It is shown that, although successful in most cases, different approaches are required to discriminate between ships and image artefacts.
Aerospace and Electronic Systems, IEEE …, Jan 1, 2010
Abstract Starting from the reborn international interest in lunar exploration and the widely docu... more Abstract Starting from the reborn international interest in lunar exploration and the widely documented need for hyper-accurate measurements of Earth crustal dynamics, at a high revisit frequency and on a global scale, the idea of a Moon-based interferometric synthetic ...
Proceedings of SPIE, Jan 1, 2011
ABSTRACT Maritime surveillance problems are drawing the attention of multiple institutional actor... more ABSTRACT Maritime surveillance problems are drawing the attention of multiple institutional actors. National and international security agencies are interested in matters like maritime traffic security, maritime pollution control, monitoring migration flows and detection of illegal fishing activities. Satellite imaging is a good way to identify ships but, characterized by large swaths, it is likely that the imaged scenes contain a large number of ships, with the vast majority, hopefully, performing legal activities. Therefore, the imaging system needs a supporting system which identifies legal ships and limits the number of potential alarms to be further monitored by patrol boats or aircrafts. In this framework, spaceborne Synthetic Aperture Radar (SAR) sensors, terrestrial AIS and the ongoing satellite AIS systems can represent a great potential synergy for maritime security. Starting from this idea the paper develops different designs for an AIS constellation able to reduce the time lag between SAR image and AIS data acquisition. An analysis of SAR-based ship detection algorithms is also reported and candidate algorithms identified.
Proceedings of SPIE, Jan 1, 2009
Performance analysis of Bistatic Synthetic Aperture Radar (SAR) characterized by arbitrary geomet... more Performance analysis of Bistatic Synthetic Aperture Radar (SAR) characterized by arbitrary geometric configurations is usually complex and time-consuming since system impulse response has to be evaluated by bistatic SAR processing. This approach does not allow derivation of general equations regulating the behaviour of image resolutions with varying the observation geometry. It is well known that for an arbitrary configuration of bistatic SAR there are not perpendicular range and azimuth directions, but the capability to produce an image is not prevented as it depends only on the possibility to generate image pixels from time delay and Doppler measurements. However, even if separately range and Doppler resolutions are good, bistatic SAR geometries can exist in which imaging capabilities are very poor when range and Doppler directions become locally parallel. The present paper aims to derive analytical tools for calculating the geometric resolutions of arbitrary configuration of bistatic SAR. The method has been applied to a hybrid bistatic Synthetic Aperture Radar formed by a spaceborne illuminator and a receiving-only airborne forward-looking Synthetic Aperture Radar (F-SAR). It can take advantage of the spaceborne illuminator to dodge the limitations of monostatic FSAR. Basic modeling and best illumination conditions have been detailed in the paper.
Synthetic Aperture Radar (EUSAR), 2008 …, Jan 1, 2008
... Antonio, Moccia, University of Naples, Italy Alfredo, Renga, University of Naples, Italy ... ... more ... Antonio, Moccia, University of Naples, Italy Alfredo, Renga, University of Naples, Italy ... [5] PA Rosen, S. Hensley, IR Joughin, FK Li, SN Madsen, E. Rodriguez, and RM Gold-stein, Synthetic Aperture Radar Interfero-metry, Proceedings of the IEEE, 88, 3, 333-382, 2000. ...
Advances in Space Research, Jan 1, 2011
GPS relative navigation filters could benefit notably from an accurate modeling of the ionospheri... more GPS relative navigation filters could benefit notably from an accurate modeling of the ionospheric delays, especially over large baselines (>100 km) where double difference delays can be higher than several carrier wavelengths. This paper analyzes the capability of ionospheric path delay models proposed for spaceborne GPS receivers in predicting both zero-difference and double difference ionospheric delays. We specifically refer to relatively simple ionospheric models, which are suitable for real-time filtering schemes. Specifically, two ionospheric delay models are evaluated, one assuming an isotropic electron density and the other considering the effect on the electron density of the Sun aspect angle. The prediction capability of these models is investigated by comparing predicted ionospheric delays with measured ones on real flight data from the Gravity Recovery and Climate Experiment mission, in which two satellites fly separated of more than 200 km. Results demonstrate that both models exhibit a correlation in the excess of 80% between predicted and measured double-difference ionospheric delays. Despite its higher simplicity, the isotropic model performs better than the model including the Sun effect, being able to predict double differenced delays with accuracy smaller than the carrier wavelength in most cases. The model is thus fit for supporting integer ambiguity fixing in real-time filters for relative navigation over large baselines. Concerning zerodifference ionospheric delays, results demonstrate that delays predicted by the isotropic model are highly correlated (around 90%) with those estimated using GPS measurements. However, the difference between predicted and measured delays has a root mean square error in the excess of 30 cm. Thus, the zero-difference ionospheric delays model is not likely to be an alternative to methods exploiting carrier-phase observables for cancelling out the ionosphere contribution in single-frequency absolute navigation filters.
Geoscience and Remote Sensing, IEEE …, Jan 1, 2009
This paper aims to investigate the performance of stereoradargrammetric methods applied to spaceb... more This paper aims to investigate the performance of stereoradargrammetric methods applied to spaceborne monostatic-bistatic synthetic aperture radar (SAR) data for digital elevation model (DEM) generation. Stereoradargrammetric techniques for robust DEM generation were successfully experienced on monostatic repeat-pass SIR-A, SIR-B, SIR-C/X-SAR, ERS1/2, JERS-1, and Radarsat data. However, novel configurations achievable by modern spacecraft flying in formation will allow for the attainment of very large baselines between the antennas in a single-pass bistatic geometry so that the height determination accuracy can benefit from both stereo effect and simultaneous acquisition. Five models for relief reconstruction by monostatic-bistatic SAR stereoradargrammetry are presented, and an error budget is assessed for each of them. Results of the sensitivity analysis exhibit metric accuracy, and therefore, the technique could be applied for height reconstruction as a methodology complementary to SAR interferometry.
Submerged palaeolandscapes can contain pristine underwater heritage. Regular monitoring of these ... more Submerged palaeolandscapes can contain pristine underwater heritage. Regular monitoring of these areas is essential to assess and mitigate threats from development including construction, mining, and commercial trawling. While bathymetry alone may be insufficient to detect submerged palaeolandscape features, it can nonetheless recognize previously mapped structures that have a topographic
expression. The Sentinel-1 constellation will provide unprecedented access to freely available, high-resolution Synthetic Aperture Radar (SAR) data, acquired systematically and with long-term continuity, and may constitute a cost-effective solution for the monitoring of submerged alaeolandscapes. The article shows the application of a
recently developed bathymetric algorithmto Sentinel-1 SAR data over a region of the southern North Sea. Results show general agreement with water depth data obtained from the European Marine Observation and Data Network portal for bathymetry (EMODnet). To assess the support that SAR bathymetry can provide to the analysis of submerged palaeolandscapes, the Sentinel-1-derived water depths were compared to a alaeolandscape map of the same area produced
by the North Sea Palaeolandscapes Project (NSPP). Results show a clear correspondence between certain topographic structures identified in the Sentinel-1 water depth map and features interpreted by the NSPP as early Holocene lakes, rivers, and landscape topography