MirrorSAR: An HRWS Add-On for Single-Pass Multi-Baseline SAR Interferometry

Mittermayer, Josef; Krieger, Gerhard; Bojarski, Allan; Zonno, Mariantonietta; Villano, Michelangelo; Pinheiro, Muriel; Bachmann, Markus; Buckreuss, Stefan; Moreira, Alberto

doi:10.1109/tgrs.2021.3132384

Cited by 30 publications

(22 citation statements)

References 39 publications

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“…While an accurate performance assessment can only be made for a specific system, simple simulations under conservative assumptions show the effectiveness of the technique, which could be useful for the design of future spaceborne interferometric SAR systems, such as High Resolution Wide Swath (HRWS) [36], as well as for the enhanced exploitation of current ones.…”

Section: Discussionmentioning

confidence: 99%

Decorrelating Ambiguities in SAR Interferometry Through Slight PRI Variation

Villano

Peixoto

Ustalli

et al. 2022

IEEE Trans. Geosci. Remote Sensing

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Synthetic aperture radar (SAR) interferometry is a well-established technique for producing high-resolution digital elevation models (DEMs) of the Earth's surface and measuring displacements on different time scales. Observations of SAR interferograms, however, show that azimuth ambiguities can be coherently imaged and may lead to phase biases and coherence losses that significantly degrade the interferometric performance. Whereas imposing very low ambiguity levels may represent a severe design constraint for a spaceborne SAR system, a slight variation of the pulse repetition interval (PRI) is a new, simple, yet effective technique to decorrelate ambiguities, which in turn reduces the phase biases and coherence losses without substantially affecting the imaged swath width. An additional benefit of the PRI variation is that range ambiguities also become decorrelated. This paper addresses two cases: For the repeat-pass case, slightly different pulse repetition frequencies (PRFs) can be used for the two acquisitions and the minimum required PRF difference can be analytically derived resorting to the power spectral density of the ambiguous signals; For the single-pass case, a slight variation of the PRI during the common acquisition is an effective solution, in case an along-track baseline is present. In particular, a square wave PRI variation scheme outperforms sinusoidal or random ones. Finally, simulations using TanDEM-X data are presented to show the improvement in interferogram and DEM quality resulting from ambiguity decorrelation. This work is relevant for the design of future spaceborne interferometric SAR systems and for the enhanced exploitation of current ones.

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Section: Discussionmentioning

confidence: 99%

Decorrelating Ambiguities in SAR Interferometry Through Slight PRI Variation

Villano

Peixoto

Ustalli

et al. 2022

IEEE Trans. Geosci. Remote Sensing

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“…where p VZC,n (η) can be obtained according to (6). Thus, the distance between the estimated and real coordinates of Sat n is given as follows…”

Section: Real Satellite Positionsmentioning

confidence: 99%

“…SAR systems to provide equivalent or superior performance compared to the state-of-the-art SAR systems currently with a minor cost and higher robustness towards failure [6].…”

mentioning

confidence: 99%

An Imaging Method for Spaceborne Cooperative Multistatic SAR Formations With Nonzero Cross-Track Baselines

Lin

Deng

Zhang

et al. 2022

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

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Spaceborne multistatic synthetic aperture radar (M-SAR) formations can deploy multiple spatially separated receiving phase centers along the along-track (AT) direction to achieve high-resolution wide-swath. However, the cross-track (XT) separation between the spacecraft is inevitable due to the formation design like orbital safety and application potential like the XT interferometry. In addition, the different motion vectors of two or more satellites caused by the Helix formation will lead to the difference of the Doppler parameters at the same range gate. Therefore, nonzero XT baselines and space-variant characteristics pose new challenges to the focusing and phase-preserving of the M-SAR imaging. To this end, an imaging method for spaceborne cooperative M-SAR formations with nonzero XT baselines is proposed in this paper. Firstly, an spaceborne cooperative M-SAR formation is demonstrated. Afterwards, the imaging method is described in detail. The motion compensation technology and the idea of partitioned equivalent velocity are adopted to solve the problems of nonzero XT baselines and spacevariant characteristics, respectively. Finally, the simulations of point targets and distributed targets are carried out to verify the proposed method, and the results show that the precise focusing of spaceborne cooperative M-SAR with nonzero XT baselines can be achieved by the proposed imaging method.Index Terms-Multistatic synthetic aperture radar (M-SAR), M-SAR formations, M-SAR imaging processing, nonzero crosstrack(XT) baselines. I. INTRODUCTIONS PACEBORNE multistatic synthetic aperture radar (SAR) is an extension of the concept of bistatic SAR (BiSAR), which is characterized by deploying multiple physically separate transceiver to obtain three or more simultaneous echo data sets [1], [2]. Multistatic SAR (M-SAR) has many unique characteristics that meet the application requirements of the nextgeneration spaceborne SAR system, such as high-resolution wide-swath (HRWS) imaging, along-track (AT) interferometry, cross-track (XT) interferometry and so on, so it has received extensive attention [3]-[5]. Another trend is adopting cheaper systems with the intention to shift the complexity from the space segment to software. Thus, small satellites which received echoes only can be deployed in the formation of M-

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“…Many techniques have been developed to acquire HRWS images. In [3], multiple highpower beams with different azimuth phase centers were radiated from a satellite-borne HRWS SAR, around which three transponder-like MirrorSAR satellites orbited to configure multiple interferometric baselines in a single pass. The simulated resolution was 1.5 m and the swath width was 20 km.…”

Section: Introductionmentioning

confidence: 99%

“…The simulated resolution was 1.5 m and the swath width was 20 km. Significant trajectory curvature of spaceborne SAR is difficult to compensate for completely via signal processing, and the nested helix orbit of MirrorSAR in [3] makes this issue even worse, leading to degraded resolution. Compared with practical HRWS applications, resolution of 1.5 m and swath width of 20 km seem to be insufficient.…”

Section: Introductionmentioning

confidence: 99%

Multi-Channel SAR Imaging on Cruising Ships with Sub-Orbital Spaceplane

Kiang

2022

Remote Sensing

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A multi-channel synthetic aperture radar (SAR) on board a spaceplane orbiting near the top of the atmosphere is proposed to acquire images of cruising ships. Low pulse repetition frequency (PRF) is required for high-resolution wide-swath (HRWS) imaging, leading to inevitable problems of azimuth spectrum aliasing (ASA) and azimuth Doppler ambiguity (ADA). In this work, we propose a phase matching technique to solve the ASA problem in restoring the azimuth spectrum. A multi-stage compressive-sensing (CS) technique is also proposed to solve both ADA and ASA problems. Five similar types of cruising ship are simulated to verify the efficacy of the proposed approach, at different levels of signal-to-noise ratio. Indices of geometry match, intensity match, and structural similarity are used to identify different ships from the acquired SAR images.

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MirrorSAR: An HRWS Add-On for Single-Pass Multi-Baseline SAR Interferometry

Cited by 30 publications

References 39 publications

Decorrelating Ambiguities in SAR Interferometry Through Slight PRI Variation

Decorrelating Ambiguities in SAR Interferometry Through Slight PRI Variation

An Imaging Method for Spaceborne Cooperative Multistatic SAR Formations With Nonzero Cross-Track Baselines

Multi-Channel SAR Imaging on Cruising Ships with Sub-Orbital Spaceplane

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