Generalized Continuous Wave Synthetic Aperture Radar

Nan, Yijiang

Generalized Continuous Wave Synthetic Aperture Radar

Nan, Yijiang

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Publication Type:: Thesis
Issue Date:: 2019

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Field	Value	Language
dc.contributor.author	Nan, Yijiang
dc.date.accessioned	2020-05-07T00:34:55Z
dc.date.available	2020-05-07T00:34:55Z
dc.date.issued	2019
dc.identifier.uri	http://hdl.handle.net/10453/140524
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_AU
dc.description.abstract	Synthetic aperture radar (SAR) suffers from several intrinsic limitations caused by the slow time sampling in azimuth. In this thesis, a generalized continuous wave synthetic aperture radar (GCW-SAR) is developed based on one-dimensional (1-D) continuous wave (CW) signalling, thus removing these limitations. GCW-SAR reconstructs a radar image originally by correlating the received one-dimensional raw data after self-interference cancellation (SIC) with predetermined location dependent reference signals. The SIC in GCW-SAR is discussed and then the system geometry and the original imaging method are proposed. To reduce the complexity, a novel piecewise constant Doppler (PCD) algorithm based on the linear approximation of the slant range, is proposed reconstructing a SAR image recursively in azimuth. Additionally, a faster and more flexible PCD implementation, called decimated PCD algorithm, is proposed, by which the image azimuth spacing can be extended further reducing the computational cost significantly. The PCD algorithm is the key technique for the GCW-SAR. This thesis presents a theoretical PCD imaging performance analysis. Firstly, the difference between conventional SAR imaging and PCD imaging is revealed. Exact ambiguity function expressions of the PCD imaging in range and azimuth are then derived respectively. An error function of the PCD imaging is further defined and shown to be a function of an image quality factor to quantify the imaging performance. The decimated PCD imaging error is also analyzed accordingly. Passive GCW-SAR system and millimeter wave GCW-SAR system with deramp-on-receive are proposed respectively. A modified PCD algorithm suited for passive GCW-SAR is proposed to remove the conventional passive SAR limitations. Using deramping technique can drastically reduce the receiving sampling rate and the millimeter wave carrier enables high azimuth resolution as well as short synthetic aperture which in turn significantly reduces the imaging computational complexity. The effects of deramp-on-receive in PCD imaging is analyzed accordingly. Finally, a real GCW-SAR experimental system is developed and the experimental results are presented. This practical system consists of four subsystems, i.e., receiver frontend subsystem, radar control subsystem, positioning control subsystem and digital imaging subsystem. The first two parts are constructed by using the AWR1843 single-chip 77-GHz FMCW radar sensor made by Texas Instruments, the third by using the linear moving platform made by FUYU Technology company, and the digital imaging is possessed by MATLAB off-line processing in a personal computer (PC). The experimental results validate the advantages of the proposed GCW-SAR system.	en_AU
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/140524/2/02whole.pdf
dc.rights	au.edu.uts.lib/ppc
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Generalized Continuous Wave Synthetic Aperture Radar	en_AU
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Synthetic aperture radar (SAR) suffers from several intrinsic limitations caused by the slow time sampling in azimuth. In this thesis, a generalized continuous wave synthetic aperture radar (GCW-SAR) is developed based on one-dimensional (1-D) continuous wave (CW) signalling, thus removing these limitations. GCW-SAR reconstructs a radar image originally by correlating the received one-dimensional raw data after self-interference cancellation (SIC) with predetermined location dependent reference signals. The SIC in GCW-SAR is discussed and then the system geometry and the original imaging method are proposed. To reduce the complexity, a novel piecewise constant Doppler (PCD) algorithm based on the linear approximation of the slant range, is proposed reconstructing a SAR image recursively in azimuth. Additionally, a faster and more flexible PCD implementation, called decimated PCD algorithm, is proposed, by which the image azimuth spacing can be extended further reducing the computational cost significantly. The PCD algorithm is the key technique for the GCW-SAR. This thesis presents a theoretical PCD imaging performance analysis. Firstly, the difference between conventional SAR imaging and PCD imaging is revealed. Exact ambiguity function expressions of the PCD imaging in range and azimuth are then derived respectively. An error function of the PCD imaging is further defined and shown to be a function of an image quality factor to quantify the imaging performance. The decimated PCD imaging error is also analyzed accordingly. Passive GCW-SAR system and millimeter wave GCW-SAR system with deramp-on-receive are proposed respectively. A modified PCD algorithm suited for passive GCW-SAR is proposed to remove the conventional passive SAR limitations. Using deramping technique can drastically reduce the receiving sampling rate and the millimeter wave carrier enables high azimuth resolution as well as short synthetic aperture which in turn significantly reduces the imaging computational complexity. The effects of deramp-on-receive in PCD imaging is analyzed accordingly. Finally, a real GCW-SAR experimental system is developed and the experimental results are presented. This practical system consists of four subsystems, i.e., receiver frontend subsystem, radar control subsystem, positioning control subsystem and digital imaging subsystem. The first two parts are constructed by using the AWR1843 single-chip 77-GHz FMCW radar sensor made by Texas Instruments, the third by using the linear moving platform made by FUYU Technology company, and the digital imaging is possessed by MATLAB off-line processing in a personal computer (PC). The experimental results validate the advantages of the proposed GCW-SAR system.

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