摘要 :
GEOSAR has the characteristics of wide coverage and short revisit time. But when the GEOSAR is both used as a transmitter and a receiver, its advantages is not well exploited. If an airplane or a LEO satellite is replaced as a pla...
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GEOSAR has the characteristics of wide coverage and short revisit time. But when the GEOSAR is both used as a transmitter and a receiver, its advantages is not well exploited. If an airplane or a LEO satellite is replaced as a platform of the receiver, we can not only observe the interesting regions flexibly, but also achieve finer resolution. However, the geometry of the BiSAR is complicated. Thus, it's not easy to acquire the resolution characteristics of an arbitrary BiSAR system. In this paper, starting with the resolution on the basic plane of a BiSAR system, and combining the resolution's projection relation between the basic plane and the plane tangent to the earth's surface, we obtain the resolution ellipse's expression on the ground. Finally, based on the expression, we optimize the two parameters including the signal bandwidth and the synthetic aperture time in order to realize the satisfactory resolution in a BiSAR system.
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摘要 :
GEOSAR has the characteristics of wide coverage and short revisit time. But when the GEOSAR is both used as a transmitter and a receiver, its advantages is not well exploited. If an airplane or a LEO satellite is replaced as a pla...
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GEOSAR has the characteristics of wide coverage and short revisit time. But when the GEOSAR is both used as a transmitter and a receiver, its advantages is not well exploited. If an airplane or a LEO satellite is replaced as a platform of the receiver, we can not only observe the interesting regions flexibly, but also achieve finer resolution. However, the geometry of the BiSAR is complicated. Thus, it's not easy to acquire the resolution characteristics of an arbitrary BiSAR system. In this paper, starting with the resolution on the basic plane of a BiSAR system, and combining the resolution's projection relation between the basic plane and the plane tangent to the earth's surface, we obtain the resolution ellipse's expression on the ground. Finally, based on the expression, we optimize the two parameters including the signal bandwidth and the synthetic aperture time in order to realize the satisfactory resolution in a BiSAR system.
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摘要 :
Multiple-input multiple-output SAR (MIMO-SAR) can transmit multiple waveforms and separate the radar echoes, which enables it to work in several modes simultaneously such as spotlight, sliding spotlight and strip-map modes. Howeve...
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Multiple-input multiple-output SAR (MIMO-SAR) can transmit multiple waveforms and separate the radar echoes, which enables it to work in several modes simultaneously such as spotlight, sliding spotlight and strip-map modes. However, most of the existing waveforms are not well orthogonal, which cannot separate the echo completely and thus degrade the performance of MIMO-SAR applications. To solve this problem, a novel digital beam-forming (DBF) method for multi-modes MIMO-SAR based on APC waveforms is proposed in this paper. Due to the Doppler shift effect of the APC waveforms, the spectrum of overlapped echoes change with azimuth angles. Therefore, the digital beam-forming (DBF) in azimuth can be used to separate the echoes well. Finally, simulations of both point target and distributed target are conducted to validate the effectiveness of the proposed method.
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摘要 :
As an emerging technique to obtain remotely sensed data, geosynchronous synthetic aperture radar (GEOSAR) is still at the infant stage for the development of the basic theory although some prediction indicates that the first GEOSA...
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As an emerging technique to obtain remotely sensed data, geosynchronous synthetic aperture radar (GEOSAR) is still at the infant stage for the development of the basic theory although some prediction indicates that the first GEOSAR satellite would be in orbit around 2020. Before the launching, a series of challenges in GEOSAR must be addressed and the feasible solutions should be carried out. Thus, systematic analyses of challenges and solutions in GEOSAR are proposed here. In this paper, the GEOSAR has been studied through analyses of bi-static imaging geometry, signal model, Doppler characteristics, Doppler bandwidth and synthetic aperture time, and resolution evaluation of the GEOSAR imagery, in which both challenges and solutions are included.
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摘要 :
As an emerging technique to obtain remotely sensed data, geosynchronous synthetic aperture radar (GEOSAR) is still at the infant stage for the development of the basic theory although some prediction indicates that the first GEOSA...
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As an emerging technique to obtain remotely sensed data, geosynchronous synthetic aperture radar (GEOSAR) is still at the infant stage for the development of the basic theory although some prediction indicates that the first GEOSAR satellite would be in orbit around 2020. Before the launching, a series of challenges in GEOSAR must be addressed and the feasible solutions should be carried out. Thus, systematic analyses of challenges and solutions in GEOSAR are proposed here. In this paper, the GEOSAR has been studied through analyses of bi-static imaging geometry, signal model, Doppler characteristics, Doppler bandwidth and synthetic aperture time, and resolution evaluation of the GEOSAR imagery, in which both challenges and solutions are included.
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摘要 :
The traditional SAR motion parameter estimation method based on physical or statistical models has problems such as poor versatility and low efficiency. Starting from SAR defocused images, combined with deep learning technology is...
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The traditional SAR motion parameter estimation method based on physical or statistical models has problems such as poor versatility and low efficiency. Starting from SAR defocused images, combined with deep learning technology is expected to solve the above problems. To this end, this paper studies a SAR motion error parameter estimation algorithm combined with the convolutional neural network, which uses GoogLeNet network architecture to build training networks. Based on the idea of image classification, the motion error of the airborne SAR is estimated. Finally, the influence of scene types on parameter estimation network training is analyzed experimentally.
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摘要 :
For the airborne SAR imaging, the motion compensation (MOCO) is required because of the phase error caused by the atmospheric turbulence. In the case of ultrahigh-resolution and wide-swath, the phase error may be range-dependent (...
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For the airborne SAR imaging, the motion compensation (MOCO) is required because of the phase error caused by the atmospheric turbulence. In the case of ultrahigh-resolution and wide-swath, the phase error may be range-dependent (RD), which may induce a RD residual-RCM after the correction of range cell migration (RCM) by using the range migration algorithm (RMA). Currently, phase gradient autofocus (PGA) is widely used to estimate the phase error from the raw data. However, the RD residual-RCM may degrade the accuracy of the PGA. To overcome such a problem, we present a CZT correction algorithm to correct the RD residual-RCM. Processing of airborne real data validates the effectiveness of the proposed algorithm.
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