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This paper describes a geocoding procedure that relies on a polynomial model derived from the imaging geometry without loss of accuracy. By using polynomial model, one can effectively eliminate the iterative process to find an ima...
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This paper describes a geocoding procedure that relies on a polynomial model derived from the imaging geometry without loss of accuracy. By using polynomial model, one can effectively eliminate the iterative process to find an image pixel corresponding to each output grid point. With the imaging geometry and ephemeris data, a geo-location polynomial can be constructed from grid points that are produced by solving three equations simultaneously. And, in order to correct the local distortions induced by the geometry and terrain height, a distortion model has been incorporated in the procedure, which is a function of incidence angle and height at each pixel position. With this function, it is straightforward to calculate the pixel displacement due to distortions and then pixels are assigned to the output grid by re-sampling the displaced pixels.
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In previous work, we proposed to generate random samples using chaotic maps. More specifically, we demonstrated that Gaussian samples can be obtained via two random number generators that utilize first order or second order chaoti...
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In previous work, we proposed to generate random samples using chaotic maps. More specifically, we demonstrated that Gaussian samples can be obtained via two random number generators that utilize first order or second order chaotic maps. In this paper we extend this work and propose to utilize the chaos-based random generators to develop a Gaussian FM signal that can be exploited for radar imaging. For this purpose, we fine-tune the chaotic map parameters of the Gaussian FM signal until we obtain a white wide-band spectrum, which is computed as an ensemble average, and analyze the corresponding ambiguity surface of the signal. We observe that the ensemble average of the ambiguity surface approaches an ideal two dimensional delta with uniformly distributed sidelobes on the range-Doppler plane. On average the sidelobes of the surface have intensity inversely proportional to the length of the processed echo. For completeness, we compare the variance of the Gaussian FM ambiguity function to that of a random binary phase code with comparable bandwidth. Furthermore, we show through simulations that Fourier processing of the Gaussian FM signal can yield a high-resolution range-Doppler image aircraft with prominent point scattering points over a substantial SNR dynamic range.
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摘要 :
In previous work, we proposed to generate random samples using chaotic maps. More specifically, we demonstrated that Gaussian samples can be obtained via two random number generators that utilize first order or second order chaoti...
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In previous work, we proposed to generate random samples using chaotic maps. More specifically, we demonstrated that Gaussian samples can be obtained via two random number generators that utilize first order or second order chaotic maps. In this paper we extend this work and propose to utilize the chaos-based random generators to develop a Gaussian FM signal that can be exploited for radar imaging. For this purpose, we fine-tune the chaotic map parameters of the Gaussian FM signal until we obtain a white wide-band spectrum, which is computed as an ensemble average, and analyze the corresponding ambiguity surface of the signal. We observe that the ensemble average of the ambiguity surface approaches an ideal two dimensional delta with uniformly distributed sidelobes on the range-Doppler plane. On average the sidelobes of the surface have intensity inversely proportional to the length of the processed echo. For completeness, we compare the variance of the Gaussian FM ambiguity function to that of a random binary phase code with comparable bandwidth. Furthermore, we show through simulations that Fourier processing of the Gaussian FM signal can yield a high-resolution range-Doppler image aircraft with prominent point scattering points over a substantial SNR dynamic range.
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摘要 :
In previous work, we proposed to generate random samples using chaotic maps. More specifically, we demonstrated that Gaussian samples can be obtained via two random number generators that utilize first order or second order chaoti...
展开
In previous work, we proposed to generate random samples using chaotic maps. More specifically, we demonstrated that Gaussian samples can be obtained via two random number generators that utilize first order or second order chaotic maps. In this paper we extend this work and propose to utilize the chaos-based random generators to develop a Gaussian FM signal that can be exploited for radar imaging. For this purpose, we fine-tune the chaotic map parameters of the Gaussian FM signal until we obtain a white wide-band spectrum, which is computed as an ensemble average, and analyze the corresponding ambiguity surface of the signal. We observe that the ensemble average of the ambiguity surface approaches an ideal two dimensional delta with uniformly distributed sidelobes on the range-Doppler plane. On average the sidelobes of the surface have intensity inversely proportional to the length of the processed echo. For completeness, we compare the variance of the Gaussian FM ambiguity function to that of a random binary phase code with comparable bandwidth. Furthermore, we show through simulations that Fourier processing of the Gaussian FM signal can yield a high-resolution range-Doppler image aircraft with prominent point scattering points over a substantial SNR dynamic range.
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Synthetic Aperture Sonar (SAS) performance is limited by motion errors of the towfish. It is necessary to require the towfish moving in a straight line in order to improve the imaging efficiency by Fast Fourier Transformation (FFT...
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Synthetic Aperture Sonar (SAS) performance is limited by motion errors of the towfish. It is necessary to require the towfish moving in a straight line in order to improve the imaging efficiency by Fast Fourier Transformation (FFT). However, the towfish could hardly move along a straight line because of some factors such as ocean wave, ocean current and tide. All kinds of motion errors could incur phase error in echo signal and make the quality of final image decline. The aim of this work is to lighten the influence of the motion errors in final image. Motion errors of towfish are analyzed in detail and a motion compensation (MOCO) scheme based on Range-Doppler imaging algorithm is proposed. The simulation trials validate the analysis and the scheme.
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摘要 :
Synthetic Aperture Sonar (SAS) performance is limited by motion errors of the towfish. It is necessary to require the towfish moving in a straight line in order to improve the imaging efficiency by Fast Fourier Transformation (FFT...
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Synthetic Aperture Sonar (SAS) performance is limited by motion errors of the towfish. It is necessary to require the towfish moving in a straight line in order to improve the imaging efficiency by Fast Fourier Transformation (FFT). However, the towfish could hardly move along a straight line because of some factors such as ocean wave, ocean current and tide. All kinds of motion errors could incur phase error in echo signal and make the quality of final image decline. The aim of this work is to lighten the influence of the motion errors in final image. Motion errors of towfish are analyzed in detail and a motion compensation (MOCO) scheme based on Range-Doppler imaging algorithm is proposed. The simulation trials validate the analysis and the scheme.
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A commonly known design requirement for synthetic aperture (SAR) systems is the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So in conventional SAR, there is a well known trade-off between unambigu...
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A commonly known design requirement for synthetic aperture (SAR) systems is the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So in conventional SAR, there is a well known trade-off between unambiguous swathwidth and resolution. However, if spatial sampling is added, the maximum unambiguous illumination area will increase with the number of receivers; through this method multiple beams can be formed to reject range-Doppler ambiguities. As is well known, multistatic synthetic aperture radar operates with multiple receive atennas distributed among different platforms which can be used to increase the special sampling. And constellations of formation-flying microsatellites are currently under study in the field of remote sensing. Basing on this multistatic modes, this paper is intended to study signal processing method of SAR Doppler ambiguities resolving to improve image quality.
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摘要 :
A commonly known design requirement for synthetic aperture (SAR) systems is the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So in conventional SAR, there is a well known trade-off between unambigu...
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A commonly known design requirement for synthetic aperture (SAR) systems is the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So in conventional SAR, there is a well known trade-off between unambiguous swath-width and resolution. However, if spatial sampling is added, the maximum unambiguous illumination area will increase with the number of receivers; through this method multiple beams can be formed to reject range-Doppler ambiguities. As is well known, multistatic synthetic aperture radar operates with multiple receive antennas distributed among different platforms which can be used to increase the special sampling. And constellations of formation-flying microsatellites are currently under study in the field of remote sensing. Basing on this multistatic modes, this paper is intended to study signal processing method of SAR Doppler ambiguities resolving to improve image quality.
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A complete vehicleborne Bistatic Synthetic Aperture Radar (SAR) imaging experiment is presented in this paper. Some new technologies were used to solve synchronization problems. An algorithm named the Glide Window Echo CFAR was us...
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A complete vehicleborne Bistatic Synthetic Aperture Radar (SAR) imaging experiment is presented in this paper. Some new technologies were used to solve synchronization problems. An algorithm named the Glide Window Echo CFAR was used to realize time synchronization and collect the echo. High stable local oscillator was employed to achieve frequency and phase synchronization, and the PRF was adjusted adaptively in the Data Acquisition Device in the receive station. Finally, the Range-Doppler algorithm with range migration correction was using to image the certain scene successfully.
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摘要 :
A complete vehicleborne Bistatic Synthetic Aperture Radar (SAR) imaging experiment is presented in this paper. Some new technologies were used to solve synchronization problems. An algorithm named the Glide Window Echo CFAR was us...
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A complete vehicleborne Bistatic Synthetic Aperture Radar (SAR) imaging experiment is presented in this paper. Some new technologies were used to solve synchronization problems. An algorithm named the Glide Window Echo CFAR was used to realize time synchronization and collect the echo. High stable local oscillator was employed to achieve frequency and phase synchronization, and the PRF was adjusted adaptively in the Data Acquisition Device in the receive station. Finally, the Range-Doppler algorithm with range migration correction was using to image the certain scene successfully.
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