Performance Evaluation of a Passive Millimeter-Wave Imager
ABSTRACT A cross-correlating 186-GHz passive millimeter-wave imager has been built. The key components in the signal processing hardware are two 186-GHz receivers and a broadband complex correlator. To evaluate the performance of this imager, its point-spread function, beam pattern, baseline vector, and their variations with the scanning direction have been experimentally measured and derived. Some of these results are needed for optimizing the imager's parameter settings. Others are required for implementing the modulated-beam and modulated-scene algorithms proposed in a previous paper dealing with the imager's fringe in its point-spread function. These results will also reveal any problems in the construction process of the imager. The theoretical bases for these measurements are analyzed. Novel algorithms for deriving each antenna's point-spread function and beam pattern, as well as the imager's baseline vector from the measurement results of the imager's point-spread function and beam pattern are proposed and successfully applied in the measurements. Experimental results are presented and discussed.
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- "The SAR model is very efficient in estimating smooth PSFs. Experimental results, , have shown that PMMW systems have smoothly varying PSFs, hence supporting our choice of prior. "
Conference Paper: Simultaneous Bayesian compressive sensing and blind deconvolution[Show abstract] [Hide abstract]
ABSTRACT: The idea of compressive sensing in imaging refers to the reconstruction of an unknown image through a small number of incoherent measurements. Blind deconvolution is the recovery of a sharp version of a blurred image when the blur kernel is unknown. In this paper, we combine these two problems trying to estimate the unknown sharp image and blur kernel solely through the compressive sensing measurements of a blurred image. We present a novel algorithm for simultaneous image reconstruction, restoration and parameter estimation. Using a hierarchical Bayesian modeling followed by an Expectation-Minimization approach we estimate the unknown image, blur and hyper-parameters of the global distribution. Experimental results on simulated blurred images support the effectiveness of our method. Moreover, real passive millimeter-wave images are used for evaluating the proposed method as well as strengthening its practical aspects.Signal Processing Conference (EUSIPCO), 2012 Proceedings of the 20th European; 01/2012
Conference Paper: Wireless tomography, Part I: A novel approach to remote sensing[Show abstract] [Hide abstract]
ABSTRACT: Wireless tomography, a novel approach to remote sensing, is proposed in Part I of this series. The methodology, literature review, related work, and system engineering are presented. Concrete algorithms and hardware platforms are implemented to demonstrate this concept. Self-cohering tomography is studied in depth. More research will be reported, following this initiative.Waveform Diversity and Design Conference (WDD), 2010 International; 09/2010
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ABSTRACT: The design and testing of an active 190-GHz imaging system is presented. The system features two beam-scanning antennas, one of which transmits a vertical fan beam, and the other which receives a horizontal fan beam. By correlating the transmitted and received signals, an output is obtained that is proportional to the millimeter-wave reflectivity at the intersection of the two fan beams. Beam scanning is obtained by rotating a small subreflector within each antenna, allowing rapid scanning. The system has an angular resolution of 0.3 deg, a field of view of 14×14 deg, and operates at a standoff distance of 5 m.Journal of Electronic Imaging 10/2010; 19(4). DOI:10.1117/1.3514744 · 0.85 Impact Factor