The micro-Doppler is an effective tool for target recognition. It is hard to detect micro-Doppler induced by vibration for its small value. In our system, phase-modulated stepped-frequency waveform is used. The method...
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ISBN:
(纸本)9781479999897
The micro-Doppler is an effective tool for target recognition. It is hard to detect micro-Doppler induced by vibration for its small value. In our system, phase-modulated stepped-frequency waveform is used. The method of matching pursuit (MP) is introduced to compensate translation. Translation trajectory is approximated by Chebyshev polynomial to improve approximation accuracy under low signal-to-noise ratio. The parameters in the polynomial are estimated by MP. To improve the performance of MP, simulated annealing is used. The operation of translation parameters estimation is performed in frequency domain before pulse compression. After translation compensation and pulse compression, Doppler component induced by rotation is mitigated by phase fitting. After compensation of translation and rotation, micro-Doppler is extracted from the result of motion compensation based on vibration model. Simulation and experiment data are used to testify our method.
This paper proposed a new focusing approach for the bistatic SAR systems with a GNSS(Global Navigation Satellite System) satellite as the transmitter. Because of the long integration time the inherited curvature of th...
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This paper proposed a new focusing approach for the bistatic SAR systems with a GNSS(Global Navigation Satellite System) satellite as the transmitter. Because of the long integration time the inherited curvature of the transmitter’s trajectory was adopted and the spatial variance of the equivalent velocity was derived under the principal of equivalent slant range model in the system signal model. The proposed focusing approach consists of two-step processing. Firstly, the general Doppler phase from constant velocity of the echo data is focused by modified Stolt mapping. Secondly, the residual nonlinear Doppler phase due to velocity variation is compensated by means of block-processing-based adaptive phase compensation to achieve large scene focusing. The simulation and experimental results validate the proposed algorithm in GNSS-based Bi SAR systems.
The bistatic spaceborne/stationary In SAR configuration could be applied to generate digital elevation model(DEM). However, two factors limit the DEM precision improvement. On one hand, due to the effects of the illum...
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The bistatic spaceborne/stationary In SAR configuration could be applied to generate digital elevation model(DEM). However, two factors limit the DEM precision improvement. On one hand, due to the effects of the illuminator’s sidelobe and the high objects’ shadow, the pixels in the corresponding area might be polluted by the noise. On the other hand, owing to the presence of deviation(between the real value and the nominal value of the master/slave antenna positions), after utilizing the nominal value to compensate for the reference phase, the residual reference phase would remain. In order to solve the problems, we proposed a new bistatic DEM generation algorithm. Firstly, we applied the coherence-phase joint analysis method to select high-coherence points. Secondly, we deduced the transforming relationship from the deviation to the residual reference phase, and then compensated for the residual reference phase. In the experiment, the Yao Gan-3(an L-band spaceborne SAR) was selected as the transmitter and the two stationary receivers were mounted on the top of a tall building. The algorithm recommended in this paper was applied to process the measured bistatic data. The analysis of the results demonstrated that the elevation error of the generated DEM for some targets had been limited to the level of 1–2 m.
This paper achieves the SAR geometric correction algorithm and makes improvements based on multi-core C6678 DSPs. To solve the insufficient real-time problem, this paper improves the geometric correction, and designs ...
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This paper achieves the SAR geometric correction algorithm and makes improvements based on multi-core C6678 DSPs. To solve the insufficient real-time problem, this paper improves the geometric correction, and designs process software that can meet the real-time requirements, from the process flow, process algorithm and storage process aspects. This paper describes the multiple DPSs parallel process scheme and multi-core mapping tasks, and makes a comparison of the time-consuming before optimization and after. And after the optimization, the geometric correction's efficiency is two times of the original. After verification, the parallel process software designed in this paper can meet the real-time requirements of the project, and also has good stability.
A new threshold template algorithm is presented in this paper to improve the performance in ship detection in high-resolution synthetic aperture radar (SAR) images. The algorithm introduces SAR formation theories into...
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A new threshold template algorithm is presented in this paper to improve the performance in ship detection in high-resolution synthetic aperture radar (SAR) images. The algorithm introduces SAR formation theories into detection. First, we divide the image into tiles within which the sea background can be treated as homogeneous one. Second, we use a threshold template method to detect candidate ship pixels in each tile. The data model and point spread function model together decide the parameters of the template. Third, group candidate pixels together and exclude false alarms. The template method exploits the relationship between neighbor pixels, which characterise high-resolution images. Experiments validate the algorithm with good performance.
In the above paper [1] there are errors in several places: 1) the first lines of text at the top left of page 3; 2) equations (2) , (11), (12), (13) , and (15) ; and 3) Fig. 3 . Their correct forms are presented...
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In the above paper [1] there are errors in several places: 1) the first lines of text at the top left of page 3; 2) equations (2) , (11), (12), (13) , and (15) ; and 3) Fig. 3 . Their correct forms are presented here.
Dear editor,Synthetic aperture radar(SAR)is a powerful electro-optic sensor for maritime use regardless of impact of time and meteorological ***,ship detection plays an important role in maritime
Dear editor,Synthetic aperture radar(SAR)is a powerful electro-optic sensor for maritime use regardless of impact of time and meteorological ***,ship detection plays an important role in maritime
Polarimetric information can fully reflect the electromagnetic scattering characteristics of radar target. Compact polarization, which can reduce the system complexity while preserving the polarimetric information has...
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Polarimetric information can fully reflect the electromagnetic scattering characteristics of radar target. Compact polarization, which can reduce the system complexity while preserving the polarimetric information has become an important technique of getting polarimetric information in recent years. In this paper we propose a modified implementation for π/4 compact polarimetric mode radar, where the transmitter polarization is orientated at 45°, and the receivers are at 45° and 135° polarizations. A procedure of reconstructing the full polarimetric information and extracting the features are subsequently deduced. From experimental data, we verify the scheme can distinguish different polarimetric scattering mechanisms. The method shows potential to better reconstruct fully polarimetric data and application value in target recognition.
The Terrain Observation by Progressive Scans (TOPS) mode solves the problems existing in the conventional ScanSAR mode by steering the antenna along the azimuth direction. However, the antenna steering introduces a se...
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ISBN:
(纸本)9781509027095
The Terrain Observation by Progressive Scans (TOPS) mode solves the problems existing in the conventional ScanSAR mode by steering the antenna along the azimuth direction. However, the antenna steering introduces a serious azimuth signal aliasing both in time-domain and frequency-domain, thus traditional imaging algorithms are not available for the TOPS mode. In order to solve the azimuth signal aliasing, an efficient TOPS imaging algorithm based on spectral analysis (SPECAN) is presented in this paper, which is improved by sub-apertures division in the azimuth processing part. Only few FFTs and complex multiplications are used in the whole imaging processing, thus the algorithm has a high efficiency. What's more, in the final focused image, different ranges have the same azimuth interval and the azimuth image resolution is alterable according to the application requirements. Finally, some simulations are conducted to verify the validity of the proposed method.
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