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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 49830 (05)
- University: Sharif University of Technology
- Department: Electrical Engineering
- Advisor(s): Bastani, Mohammad Hassan
- Abstract:
- Studies regarding Multiple Input - Multiple Output synthetic aperture radars, shows promising advances in synthetic aperture imaging. Compared to conventional SAR, MIMO-SAR encompasses desirable features, namely: lower background noise, better detection rate, easier implementation of imaging modes etc. Signals used in these radars, are required to have specific properties such as orthogonality, large time-bandwidth product, high Doppler tolerance and qualified ambiguity function. Also because of the specific geometry of SAR imaging, these signals should remain orthogonal in respectively large Doppler shifts and time offsets. Through the past years, many signals are suggested in the literature, some of which show partly satisfying results. But there is a common problem in the majority of them, which is caused by the base signal used by these methods. Almost all of these articles, use Linear Frequency Modulation (LFM) as the base signal, which has low PSLR and slowly damping sidelobes. These high sidelobes, can cause higher background noise, and masking of small targets adjacent to the large ones. To be able to overcome these problems, we suggested the use of Nonlinear Frequency Modulated signals instead, and tested the result in practice. Also a special kind of phase-coded signals combined with Space-Time coding is proposed, and its effectiveness is proved
- Keywords:
- Waveform Design ; Phase Coding ; Multi-Input Multi-Output (MIMO)Radar ; Synthetic Aperture Radar (SAR) ; Nonlinear Frequency Modulation (NLFM)
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