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Research On Ultrawideband Radar Imaging Algorithm Using Time-Reversal Electromagnetic Inversion Techniques

Posted on:2014-07-16Degree:MasterType:Thesis
Country:ChinaCandidate:S H TanFull Text:PDF
GTID:2268330401472288Subject:Radio Physics
Abstract/Summary:PDF Full Text Request
Ultra-wideband (UWB) radar has a variety of practical applications including anti-terrorism, rescue missions, archaeological applications, resource exploration, and engineering detection applications due to its great capabilities in high range resolution, strong penetration capability, and strong anti-jamming ability. However, the receiving antenna will inevitably receives the clutter signals apart from the target signals, such as the antenna direct wave, the reflection wave from the air-medium interface, and so on, when UWB radar scan the detection range. And the clutter signals may cover the object signals due to their energy stronger than the target, so how to effectively remove the clutter signals is the first task in signal processing of UWB radar. Secondly, the factors of radar special sampling method and geometric feature of the background medium make the reflection point of target reflection signals deviate from the actual reflection position, so the radar detection profile is different from the actual positions of targets. Therefore, how to effectively make the target reflected signal back to its true spatial location is also a significant step in signal processing of UWB radar. In the end, the imaging technique of UWB radar is the most promising data processing method for locating hidden objects. However, the computational cost and the resolution are the important indices for evaluating an algorithm, so how to reduce the computational cost without reducing the resolution of the imaging is a significant research content of radar imaging technology. Aiming to these problems, this paper present a framework combined multiple algorithms to achieve multiple hidden targets quickly and accurately super-resolution imaging.Firstly, aiming at the problem of suppressing clutter signals, this paper adopt based on green function filter algorithm and Frequency-Wavenumber filter approach to suppress the direct wave and the experimental results show that these two filter algorithms can better filter out the direct wave and enhance the target reflected waves.Secondly, in this paper, we apply two different methods to estimate the relative dielectric constant of the soil, the relative dielectric constant and the thickness of the wall based on the difference between ground penetrating radar model and through-the-wall radar model. And then Frequency-Wavenumber migration algorithm is applied to make the object signal back to its true spatial location.Finally, the Time Reversal Multiple Signal Classification method is applied for an efficient localization and imaging of multiple targets with a high resolution in this paper. We adopt the stationary phase method to calculate the green function integral equation and the image minimum entropy technology to choose the number of nonzero eigenvalues of the time reversal operator, and then realize multiple hidden targets quickly and accurately super-resolution imaging.
Keywords/Search Tags:Ultra-wideband (UWB) radar, green function, filter algorithm, migration algorithm, parameter estimation, Time Reversal MultipleSignal Classification method, stationary phase method, minimumentropy
PDF Full Text Request
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