The on-orbit demonstration of the small SAR satellite. Initial calibration and observations

Orzel, Krzysztof; Fujimaru, S.; Obata, Toshihiro; Imaizumi, Tsutomu; Arai, Motoyuki

doi:10.1109/radarconf2248738.2022.9764261

Cited by 6 publications

(6 citation statements)

References 9 publications

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“…The development of the StriX satellites and the pre-launch performance evaluation are described by Pyne et al [41]. The satellite's main specifications and initial observations are presented in Orzel et al [11]. The initial calibration process was conducted from late April until early June 2022, as described in Orzel et al [42].…”

Section: Strix Sar Scenesmentioning

confidence: 99%

“…The plan is to launch up to 30 StriX satellites in total over the coming years, and this will change the SAR sampling scenarios completely with respect to the current state-of-the-art. Frequent SAR sampling (i.e., hourly) over a given location on Earth could facilitate a paradigm shift in the way SAR is used for monitoring and responding to disasters [11]. It might also lead to lower uncertainties when it comes to satellite-based wind resource assessment for offshore sites.…”

Section: Introductionmentioning

confidence: 99%

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Wind Retrieval from Constellations of Small SAR Satellites: Potential for Offshore Wind Resource Assessment

Badger

Fujita²,

Orzel³

et al. 2023

Energies

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The planning of offshore wind energy projects requires wind observations over long periods for the establishment of wind speed distributions. In the marine environment, high-quality in situ observations are sparse and restricted to point locations. Numerical modeling is typically used to determine the spatial variability of the wind resource. Synthetic Aperture Radar (SAR) observations from satellites can be used for retrieval of wind fields over the ocean at a high spatial resolution. The recent launch of constellations of small SAR satellites by private companies will improve the sampling of SAR scenes significantly over the coming years compared with the current sampling rates offered by multi-purpose SAR missions operated by public space agencies. For the first time, wind fields are retrieved from a series of StriX SAR scenes delivered by Synspective (Japan) and also from Sentinel-1 scenes delivered by the European Space Agency. The satellite winds are compared with wind speed observations from the FINO3 mast in the North Sea. This leads to root-mean-square errors of 1.4–1.8 m s−1 and negative biases of −0.4 m s−1 and −1.0 m s−1, respectively. Although the Geophysical Model Functions (GMF) applied for wind retrievals have not yet been tuned for StriX SAR observations, the wind speed accuracy is satisfactory. Through conditional sampling, we estimate the wind resource from current and future SAR sampling scenarios where the number of SAR satellites in orbit is increasing over time. We find that hourly samples are needed to fully capture the diurnal wind speed variability at the site investigated. A combination of SAR samples from current missions with samples from clusters of small SAR satellites can yield the necessary number of wind speed samples for accurate wind resource estimation. This is particularly important for sites with pronounced diurnal wind speed variability. An additional benefit of small SAR satellites is that wind speed variability can be mapped at the sub-km scale. The very high spatial resolution is valuable for characterizing the wind conditions in the vicinity of existing offshore wind farms.

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Section: Strix Sar Scenesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Wind Retrieval from Constellations of Small SAR Satellites: Potential for Offshore Wind Resource Assessment

Badger

Fujita²,

Orzel³

et al. 2023

Energies

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“…Ship detection, a main direction in the maritime domain [3], holds a critical role in monitoring maritime transportation, managing ports, and overseeing maritime zones [4]. In recent years, more and more SAR satellites have been successfully launched [5][6][7], with continuous advancements in collaborative observation techniques [8]. The improvement of data quality [9], the further diversity of imaging scenarios, and the continuous establishment and upgrading of SAR datasets [10,11] have greatly promoted the development of intelligent technology for the interpretation of SAR images [12].…”

Section: Introductionmentioning

confidence: 99%

Scattering-Point-Guided Oriented RepPoints for Ship Detection

Zhao,

Huang,

Liu

et al. 2024

Remote Sensing

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Ship detection finds extensive applications in fisheries management, maritime rescue, and surveillance. However, detecting nearshore targets in SAR images is challenging due to land scattering interference and non-axisymmetric ship shapes. Existing SAR ship detection models struggle to adapt to oriented ship detection in complex nearshore environments. To address this, we propose an oriented-reppoints target detection scheme guided by scattering points in SAR images. Our method deeply integrates SAR image target scattering characteristics and designs an adaptive sample selection scheme guided by target scattering points. This incorporates scattering position features into the sample quality measurement scheme, providing the network with a higher-quality set of proposed reppoints. We also introduce a novel supervised guidance paradigm that uses target scattering points to guide the initialization of reppoints, mitigating the influence of land scattering interference on the initial reppoints quality. This achieves adaptive feature learning, enhancing the quality of the initial reppoints set and the performance of object detection. Our method has been extensively tested on the SSDD and HRSID datasets, where we achieved mAP scores of 89.8% and 80.8%, respectively. These scores represent significant improvements over the baseline methods, demonstrating the effectiveness and robustness of our approach. Additionally, our method exhibits strong anti-interference capabilities in nearshore detection and has achieved state-of-the-art performance.

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“…Recently, the involvement of satellites, and specifically SAR, in Earth observation, object detection and recognition [1], [2], data communication [3], Internetof-Things (IoT) [4], and more is rapidly increasing. Therefore, the launch of more satellites and especially space-borne SAR [5]- [7] has dramatically increased and is continuously growing. Accordingly, the expected Radio Frequency Interference (RFI) from these crowded frequency bands will be extremely high, significantly affecting the overall system performance from data collection to subsequent processing stages of image interpretation and degrading the final focused SAR image quality.…”

Section: Introductionmentioning

confidence: 99%

SEMUS - An Open-Source RF-Level SAR Emulator for Interference Modelling in Spaceborne Applications

Hendy,

Kurnia,

Kraus

et al. 2023

Preprint

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<p>Earth observation has a crucial role in understanding and monitoring our planet's health and changes. Spaceborne Synthetic Aperture Radar (SAR) has become a valuable technology for Earth monitoring, leading to a massive expansion of satellite launches. However, within the limited radio frequency (RF) band, Radio Frequency Interference (RFI) poses a significant challenge for SAR technology. RFI can have a significant impact on the overall system performance and particularly on SAR image quality. To analyze and solve the interference problem, a simulator/emulator is required at the RF level to emulate and analyze the effects of different RFI sources on the final focused spaceborne SAR image. This paper presents an open-source RF-level SAR emulator for spaceborne applications called SEMUS. SEMUS is an integrated end-to-end framework for realistic spaceborne SAR scenarios that can generate raw RF data (Level-0) for an arbitrary scene and reconstruct the final SAR-focused image (Level-1). Moreover, the emulator is capable of injecting arbitrary RFI waveforms into the raw SAR data. The simulation results prove SEMUS's ability to generate high-quality Level-0 SAR data above Melbourne, Australia. Affirming its capability, SEMUS is able to reconstruct Level-1 free of RFI or contaminated with interference.</p>

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The on-orbit demonstration of the small SAR satellite. Initial calibration and observations

Cited by 6 publications

References 9 publications

Wind Retrieval from Constellations of Small SAR Satellites: Potential for Offshore Wind Resource Assessment

Wind Retrieval from Constellations of Small SAR Satellites: Potential for Offshore Wind Resource Assessment

Scattering-Point-Guided Oriented RepPoints for Ship Detection

SEMUS - An Open-Source RF-Level SAR Emulator for Interference Modelling in Spaceborne Applications

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