KEYWORDS: Antennas, Signal to noise ratio, Imaging systems, Receivers, Transmitters, Transceivers, Telecommunications, Imaging arrays, Communication theory, Systems modeling
This paper sets an optimization criterion to maximize the performance from a given aperture by providing the
geometrical locations of the antenna elements in a 'Through Wall Imaging' (TWI) system. In many real life applications
there are strict constraints on the aperture size of TWI systems in order to have portable, easy to carry and light weight
systems. Therefore it becomes very important to maximize the information capacity of objects behind the wall from a
given physical dimension. A mathematical formulation is proposed herein to quantify the performance of any proposed
geometry of an antenna array. A few examples for specific configurations are also presented and compared in different
SNR conditions.
KEYWORDS: Signal to noise ratio, Signal attenuation, Radar, Interference (communication), Optical correlators, Signal processing, 3D acquisition, 3D image processing, Free space, Antennas
An innovative approach is introduced herein for three-dimensional (3D) imaging of objects or people hidden behind obstacles such as walls. The Xaver 800, new micro-power Ultra Wideband (UWB) radar utilizes unique signal and image processing algorithms, enabling real-time acquisition and presentation of 3D images with high resolution of objects hidden behind walls. 'Xaver 800' offers the ability to perform life-saving operations with greater success and with a smaller risk to the operatives and to those they are trying to protect. Many technical challenges are encountered when working in real-world environment. Tough link-budget, distortions, and de-focusing when passing through walls with complex construction, are only a partial list of the problems an effective through-wall-imaging system should overcome. In addition, real-time operation limits the available integration time to the operational frame rate. Efficient utilization of the available integration time can improve the systems' link budget and thereby enhance the overall performance of the system. In cases where the link-budget parameters are tough, an efficient integration method can enable a reasonable refresh rate and therefore real-time operation. An approach to compensating for different attenuation sources and signal loss through 'Non-Uniform Integration' is discusses in this paper.
A new technical approach for 'Through Wall Imaging', implemented with in the Xaver 800 system is introduced in this paper. The system is a portable Ultra-wideband (UWB) micro power radar that offers a comprehensive solution for field operational use. The Xaver 800 gives the user fast and reliable 3D visual information, the system shows objects situated behind walls with sufficient resolution such that a person can be observed including his different body parts. Enabling rich imaging capabilities and ease of use, the Xaver 800 gives the user the ability to make the right decisions and to run
more efficient 'life saving' operations. One of the main problems with the current available through wall technologies is their low resolution, "Blob" like results limits their ability to be an effective tool in the field. Higher resolution can theoretically be achieved by widening the bandwidth of the UWB signals used in these systems. However, working with high bandwidth signals creates other
challenges such as the un-alignment problem. Multi channels unaligned system can result in unfocused and distorted images. This paper deals with the un-alignment problem and suggests a few methods to solve it by coherent registration. Experimental results are given to prove the effectiveness of the different methods proposed.
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