Paul Snoeij

German Aerospace Center (DLR), Köln, North Rhine-Westphalia, Germany

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Publications (74)45.92 Total impact

  • ASAR & CEOS SAR Workshop on Calibration and Validation (CEOS SAR CalVal); 11/2013
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. In contrast to SAR systems already existing in C-band like ASAR/ENVISAT or RADARSAT-2, high demands on the radiometric stability and accuracy are made for Sentinel-1. The mission depends on the method of calibrating the entire Sentinel-1 system in an efficient way. This paper describes the strategy and provides a plan of all activities required for in-flight calibration of Sentinel-1.
    ESA Living Planet Symposium 2013; 09/2013
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    ABSTRACT: The paper provides an overview of the GMES Sentinel-1 system characteristics including the SAR imaging modes and their key performance parameters as well as the specifics of related attitude and orbit control modes (i.e. roll steering mode and zero-Doppler steering mode). In addition, the Sentinel-1 SAR interferometry (InSAR) capabilities are discussed. Furthermore, the paper outlines the planned Sentinel-1 commissioning phase activities related to the in-orbit SAR system calibration and end-to-end performance verification.
    Radar Conference (RADAR), 2013 IEEE; 01/2013
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. In contrast to SAR systems already existing in C-band like ASAR/ENVISAT or RADARSAT-2, high demands on the radiometric stability and accuracy are made for Sentinel-1. The mission depends on the method of calibrating the entire Sentinel-1 system in an efficient way. This paper describes the strategy and provides a plan of all activities required for in-flight calibration of Sentinel-1.
    Proc SPIE 09/2012;
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    ABSTRACT: Two Block Adaptive Quantization (BAQ) algorithms considered for implementation on-board Sentinel-1, the Entropy Constrained BAQ (ECBAQ) and the Flexible Dynamic BAQ (FDBAQ) are investigated with real data acquired by TerraSAR-X. The two algorithms are compared with respect to the resulting signal-to-quantization-noise ratio (SQNR) and the compression rate. The results confirm the improved performance of FDBAQ to be expected for Sentinel-1 compared to the more conventional ECBAQ.
    IEEE International Geoscience and Remote Sensing Symposium (IGARSS); 07/2012
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    ABSTRACT: The forthcoming two-satellite GMES Sentinel-1 constellation is expected to render systematic surface soil moisture retrieval at 1 km resolution using C-band SAR data possible for the first time from space. Owing to the constellation?s foreseen coverage over the Sentinel-1 Land Masses acquisition region?global approximately every six days, nearly daily over Europe and Canada depending on latitude?in the high spatial and radiometric resolution Interferometric Wide Swath (IW) mode, the Sentinel-1 mission shows high potential for global monitoring of surface soil moisture by means of fully automatic retrieval techniques. This paper presents the potential for providing such a service systematically over Land Masses and in near real time using a change detection approach, concluding that such a service is?subject to the mission operating as foreseen?expected to be technically feasible. The work presented in this paper was carried out as a feasibility study within the framework of the ESA-funded GMES Sentinel-1 Soil Moisture Algorithm Development (S1-SMAD) project.
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 04/2012; 5(4):1303-1311. · 2.87 Impact Factor
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    ABSTRACT: In the framework of the EU/ESA co-funded Global Monitoring for Environment and Security (GMES) program, ESA is undertaking the development of the Sentinel-1 (S1) mission comprising a constellation of two satellites (A and B units) each carrying an imaging C-band SAR instrument. The objective of the S-1 mission is to acquire systematically and provide routinely data and information products for GMES and national services.
    Synthetic Aperture Radar, 2012. EUSAR. 9th European Conference on; 01/2012
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. This paper describes the Sentinel-1 mission, an imaging synthetic aperture radar (SAR) satellite constellation at C-band. It provides an overview of the mission requirements, its applications and the technical concept for the system.
    Geoscience and Remote Sensing Symposium (IGARSS), 2012 IEEE International; 01/2012
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. In contrast to SAR systems already existing in C-band like ASAR/ENVISAT or RADARSAT-2, high demands on the radiometric accuracy are made for Sentinel-1. This paper provides an overview of the main features of GMES Sentinel-1 System, a C-band Synthetic Aperture Radar Observatory for Earth Observation. The main system requirements are presented as drivers for the design of system, satellite and operations. The major design challenges as well as the most critical development aspects are outlined, mainly focusing on the Space Segment components.
    Radar Conference (EuRAD), 2012 9th European; 01/2012
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    ABSTRACT: The Sentinel-1 satellite carries on board a C-band Synthetic Aperture Radar built from 560 active radiating waveguide arrays. The 280 horizontally polarised waveguide arrays and the 280 vertically polarised waveguide arrays are arranged as dual-polarised pairs in sufficient proximity to allow for grating lobe free electronic steering of the S-1 SAR antenna in the elevation plane. Each waveguide array is connected to a transmit-receive module (TRM) feeding or receiving signals via their common antenna port. The SAR instrument has an internal RF Characterisation mode exploiting the phase shifting capabilities of the TRMs, that allows monitoring of the individual excitations of each waveguide array in both Tx and Rx. The present paper reports on a novel Pulse Coded Calibration (PCC) scheme, that whilst maintaining some salient features of the Hadamard based PCC, also allows to optimise the antenna active return losses. A low active return loss is beneficial to minimise the RF stress of the TRM output circuitry and improves the accuracy of the RF Characterisation itself.
    Radar Systems (Radar 2012), IET International Conference on; 01/2012
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. In particular, as part of the GMES space component, ESA is currently undertaking the development of 3 Sentinels mission families. Each Sentinel is based on a constellation of 2 satellites in the same orbital plane. This configuration allows to fulfil the revisit and coverage requirements and to provide a robust and affordable operational service. The launch of the 2nd satellite is scheduled 18 months after the launch of the 1st spacecraft of the constellation. The lifetime of the individual satellite is specified as 7 years, with consumables allowing mission extension up to 12 years. The lifecycle of the space segment is planned to be in the order of 15-20 years. The strategy for Sentinel procurement and replacement over this period is being elaborated, but will likely result in a need for 4-5 satellites of each type if the desired robustness for the service that GMES will provide is to be achieved. This paper will describe the operational and observational capabilities of the Sentinel-1 mission based on the user requirements, including potential emergency requests. An example of a pre-defined mission timeline for each and every cycle will be given.
    Proc SPIE 10/2011;
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. In particular, as part of the GMES space component, ESA is currently undertaking the development of 3 Sentinels mission families. Each Sentinel is based on a constellation of 2 satellites in the same orbital plane. This configuration allows to fulfil the revisit and coverage requirements and to provide a robust and affordable operational service. The launch of the 2nd satellite is scheduled 18 months after the launch of the 1st spacecraft of the constellation. The lifetime of the individual satellite is specified as 7 years, with consumables allowing mission extension up to 12 years. The lifecycle of the space segment is planned to be in the order of 15–20 years. The strategy for Sentinel procurement and replacement over this period is being elaborated, but will likely result in a need for 4-5 satellites of each type if the desired robustness for the service that GMES will provide is to be achieved. This paper will describe the operational and observational capabilities of the Sentinel-1 mission based on the user requirements, including potential emergency requests. An example of a pre-defined mission timeline for each and every cycle will be given.
    01/2011;
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    ABSTRACT: The EU-ESA Global Monitoring for Environment and Security (GMES) program calls for a number of different Satellites called Sentinels to be launched within the next 6 years. The first among these are the two Sentinel-1 polar orbiting sun-synchronous satellites which each carries onboard a C-band Synthetic Aperture Radar (C-SAR).
    01/2011;
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    ABSTRACT: The letter introduces a novel quantizer suited for medium to high-resolution synthetic aperture radar (SAR) systems, like the forthcoming SENTINEL-1 SAR. The Flexible Dynamic Block Adaptive Quantization (FDBAQ) extends the concept of the Block Adaptive Quantization (BAQ), used in spaceborne SAR since the Magellan mission, by adaptively tuning the quantizer rate according to the local signal-to-noise-ratio (SNR). A design is presented aiming to optimize the average bit-rate, while constraining the minimum SNR. FDBAQ optimized performance is then evaluated using backscatter maps derived from ENVIronment SATellite (ENVISAT) data.
    IEEE Geoscience and Remote Sensing Letters 11/2010; · 1.82 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. This describes the Sentinel-1 mission, as imaging synthetic aperture radar (SAR) satellite constellation at C-band. It provides an overview of mission requirements, its applications and the technical concepts for the system.
    IEEE Aerospace and Electronic Systems Magazine 09/2010; · 0.34 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. This paper describes the Sentinel-1 mission, an imaging synthetic aperture radar (SAR) satellite constellation at C-band. It provides an overview of the mission requirements, its applications and the technical concept for the system.
    Synthetic Aperture Radar (EUSAR), 2010 8th European Conference on; 07/2010
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    ABSTRACT: The PS calibration combines external devices, like corner reflectors, transponders and the stable targets to provide continuous monitoring of the radiometric quality of a SAR instrument. The aim is to provide, on the bases of image blocks (say 10 x 10 km), the precise geolocation and the polarimetric signature of each scatterer. The scheme thus requires (1) the identification of the stable targets, and (2) the characterization of their Polarimetric scattering matrix by external references. In that way, it would be possible to calibrate even a dual polarimetric system.
    Synthetic Aperture Radar (EUSAR), 2010 8th European Conference on; 07/2010
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    ABSTRACT: The Sentinel-1 C-band SAR instrument implements an internal calibration system with a minimum of dedicated calibration elements. The transmit power times receiver gain product, PG, used for correction of the image data, is obtained from five types of calibrations measurements. Leakage signals from TX to RX are the main error sources on the calibration signals. Their impact is minimised by the PCC2 (pulse coded calibration) technique. An RF Characterization mode is implemented to monitor individual elements of the antenna. This mode is based on the PCC512 pulse coded calibration technique. The expected 3sigma accuracy for internal calibration of PG is about 0.3 dB/ 3deg. The expected 3sigma accuracy of RF characterization mode is about 0.4 dB / 5deg.
    Synthetic Aperture Radar (EUSAR), 2010 8th European Conference on; 07/2010
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. This paper describes the transponder development for the Sentinel-1 mission. It provides an overview of the transponder requirements, and a potential technical concept for the implementation.
    Synthetic Aperture Radar (EUSAR), 2010 8th European Conference on; 07/2010
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    ABSTRACT: Sentinel-1 mission is designed to be a source of continuous and reliable collection of C-band SAR imagery. As part of the complete family of GMES Sentinels, Sentinel-1 guarantees continuity of C-band SAR data and products availability to scientific and institutional users who exploit satellite radar imagery since ERS 1 operations. Drivers for EO satellite missions operations are typically fast reaction and response times but also, in the case of Sentinel-1, complete Earth surface coverage within every orbit repeat cycle (12 days). Sentinel-1 mission capabilities and the defined operational scenario currently selected by the ESA Mission and System Manager will be presented in this paper.
    Synthetic Aperture Radar (EUSAR), 2010 8th European Conference on; 07/2010