Ocean Surface Observations Using the TanDEM-X Satellite Formation

Suchandt, Steffen; Runge, Hartmut

doi:10.1109/jstars.2015.2446893

Cited by 22 publications

(8 citation statements)

References 19 publications

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“…The DRA mode is especially interesting for ocean or sea surface measurements as described in [54]. The combination between DRA mode and pursuit monostatic formation can also be used for ship velocity estimation [55].…”

Section: Dra Modementioning

confidence: 99%

The TanDEM-X Mission Phases—Ten Years of Bistatic Acquisition and Formation Planning

Bachmann

Kraus

Bojarski

et al. 2021

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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TanDEM-X is a formation flying interferometer consisting of two SAR satellites. Together they acquire bistatic SAR data of the Earth in order to generate a global Digital Elevation Model as well as individual scientific interferometric data sets on user request. This paper gives an overview about ten years of acquisition and formation planning for the TanDEM-X mission. This planning on the one hand includes the derivation of the formation, i.e. the 3D distance between both satellites in orbit. On the other hand it needs to consider the regions of interest and the mission, satellite, and instrument constraints in order to effectively plan the bistatic acquisitions. During the ten years in operation TanDEM-X successfully completed various mission goals during dedicated mission phases. All these phases, their characteristics as well as the scientific and commercial outcome are described in detail.

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Section: Dra Modementioning

confidence: 99%

The TanDEM-X Mission Phases—Ten Years of Bistatic Acquisition and Formation Planning

Bachmann

Kraus

Bojarski

et al. 2021

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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“…The two satellites of the formation, i.e., TerraSAR-X and TanDEM-X, were flown in a helix orbit, which allowed for flexible XTI/ATI baselines. Thus, the sensitivities to elevation changes and moving targets were selected over a wide range [38], [39]. The TanDEM-X mission provided extremely sensitive measurements of moving targets, such as ships and tidal currents, owing to the relatively longer along-track baseline between TerraSAR-X and TanDEM-X.…”

Section: Estimation Of Ship Velocity Using Along-track Interferometry (Ati) Sarmentioning

confidence: 99%

Ship Velocity Estimation From Ship Wakes Detected Using Convolutional Neural Networks

Kang

Kim

2019

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Accurately tracking marine traffic considering security and commercial activities is still challenging despite its increasing global importance. Recently, space-borne synthetic aperture radar (SAR) is being considered to accurately monitor maritime traffic, and techniques to detect the position of ships and estimate their velocity have become essential. Here, we investigated the potential for automatic estimation of ship velocity using the azimuth offset between ships and wakes detected using convolutional neural network (CNN) coupled with SAR imagery. We found that azimuth offset is proportional to the Doppler shift effect of the back-scattered signal in SAR, thus, it relates to the radial velocity of a moving target. Consequently, we propose a method whereby a CNN is applied to automatically detect ship wakes from TanDEM-X data. In this method, ship velocity is calculated using the azimuthal distance (i.e., azimuth offset) between the stern of the detected ship and the vertex of the detected V-shape wake-determined as the intersection of two lines obtained through edge filtering and Radon transforms. The location and number of detected ships are then compared with an automatic identification system (AIS), and the calculated velocity of the ship is compared with the velocity obtained via along-track interferometry and AIS. Results show that our method automatically detects ships and wakes with accuracies of 91.0% and 93.2%, respectively, and estimates the velocity of ships with an accuracy of 0.13 m/s. This method is effective when wind velocities are not substantially higher than 5.5 m/s and ship velocities are not extremely low.

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“…s an active microwave imaging system, spaceborne synthetic aperture radar (SAR) is able to perform the two-dimensional imaging in all-weather and all-day conditions [1][2][3][4][5][6][7]. With its superior global observation capability, spaceborne SAR has been widely used in some applications such as topographic mapping, resource detection, disaster monitoring and target recognition [8][9][10][11][12]. With the increasing of application requirements, the spaceborne SAR technology is developing quickly.…”

Section: Introductionmentioning

confidence: 99%

High-Resolution Real-Time Imaging Processing for Spaceborne Spotlight SAR With Curved Orbit via Subaperture Coherent Superposition in Image Domain

Liu

Sun

Guo

et al. 2022

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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With the increasing of application requirements, the high-resolution real-time imaging processing of the spaceborne spotlight synthetic aperture radar (SAR) has been developed. Since the traditional real-time imaging algorithms have the problems that the range model has errors and the two-dimensional space-variance of the equivalent velocity caused by the curved orbit cannot be effectively eliminated. Thus this paper proposes a high-resolution real-time imaging algorithm for spaceborne spotlight SAR with curved orbit via sub-aperture coherent superposition in image domain. In this paper, the echo data are first divided into sub-apertures to avoid the azimuth spectrum aliasing. After that, the two-dimensional space-variance of the equivalent velocity caused by the curved orbit can be eliminated by the method of azimuth time scale transformation, higher-order phase compensation and introducing phase transition function. Then, the dechirp function is applied for the sub-aperture signals to obtain the partial-resolution sub-aperture images. Finally, these partial-resolution sub-aperture images are coherently superposed in the image domain to obtain the final full-resolution image of the whole echo data. Moreover, the proposed algorithm improves the real-time performance by adopting the idea that the sub-aperture data recording and sub-aperture real-time imaging processing are synchronized, which greatly accelerates the acquisition of the final full-resolution imaging result. At the end of this paper, the simulations and the real-time performance analysis are performed to validate the proposed algorithm.Index Terms-spaceborne synthetic aperture radar (SAR), spotlight mode, high-resolution real-time imaging, curved orbit, sub-aperture coherent superposition.

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Ocean Surface Observations Using the TanDEM-X Satellite Formation

Cited by 22 publications

References 19 publications

The TanDEM-X Mission Phases—Ten Years of Bistatic Acquisition and Formation Planning

The TanDEM-X Mission Phases—Ten Years of Bistatic Acquisition and Formation Planning

Ship Velocity Estimation From Ship Wakes Detected Using Convolutional Neural Networks

High-Resolution Real-Time Imaging Processing for Spaceborne Spotlight SAR With Curved Orbit via Subaperture Coherent Superposition in Image Domain

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