Modelling and Simulation of UWB Radar System for Through the Wall Imaging and Doppler Detection

Compressive Sensing (CS) is a very useful algorithm that is used in Ground Penetrating Radar (GPR) or through the wall imaging (TWI). CS generates high resolution images by decreasing the required measurement number. Although there are several recent studies about TWI with CS, they assume that targets are point like positioned at only discrete grid locations and wall thickness and its dielectric constant are perfectly is known. However, in real applications, it is not possible to know the exact target positions or estimate the wall parameters definitely. This work details the theory for CS based TWI and analyzes the imaging ability of CS. In addition, in this work, the effect of errors in unknown parameters on the imaging performance is analyzed and possible solutions are discussed.

In this study, a printed monopole antenna with well-matched impedance bandwidth, reasonable gain and omnidirectional radiation pattern for through the wall imaging (TWI) applications is proposed. This work can be divided into two parts. The antenna design process which is the first part of this study can be explained with three design stages: antenna design is initiated with a base printed monopole antenna; parasitic patch elements are applied to the base antenna in order to obtain suitable frequency region below -10 dB and -20 dB in terms of reflection coefficient parameter; finally, the antenna is modified with the slotted ground to have better impedance match below -20 dB. Lastly, the antenna design with optimized parameters is used in a TWI scenario which is the second part of this paper. The scattering parameters are measured in two sequential time steps, and the difference in these two data is used as the data of the inversion scheme for TWI scenario. The imaging process is performed via the linear sampling method and the factorization method. The numerical simulations with a realistic wall model demonstrate that the antenna is capable of detecting objects behind the wall.

Most of the existing through-the-wall imaging (TWI) methods using synthetic aperture radar (SAR) tend to apply an active system. In this paper, a novel, passive SAR (PSAR), termed TWI-PSAR, is proposed, to focus the image of multi targets behind a single-/multilayered wall. TWI-PSAR would work in a bistatic configuration using wideband sources of opportunity and a single moving platform or a stationary linear array receiver. Incident angle and frequency are considered the parameters that influence TWI image directly. A stepped frequency transmitter with single incident angle is applied to investigate the incident angle effect. It could show the capability of small angle to suppress wall effects. Zero incident angle PSAR (Z-PSAR) is exploited in TWI for enhanced target identification and feature extraction as well as wall effect mitigation. In scenarios where background measurement might not be available or wall parameters are unknown for compensation, Z-PSAR could be adopted. Compared to other conventional imaging methods such as SAR and time reversal, numerical results show the superiority of the proposed TWI system in urgent situations with unknown wall parameters, employing free-space Green’s function. Moreover, to demonstrate the effectiveness of the proposed PSAR method in a real situation, sources of opportunity that are relatively wideband and aligned in several directions, such as analog TV, Digital Video Broadcasting—Terrestrial, GSM, and WiMAX, are used to image targets behind the wall. Also, Monte Carlo method is used to show the effectiveness of TWI-PSAR in different frequency and incident angle scenarios.

Imaging techniques based on time reversal (TR) methods are particularly suited for detection of targets embedded in strongly scattering media. Through the wall scenario is a well known example of such media in which the scatterer is behind a wall which usually has a high reflection and is strongly scattering. Generally in TR imaging techniques we need to know the Green's function of the medium and the exact location of the transmitter and receiver antennas. We have applied a new method (Time Reversal - Independent Component Analysis (TR-ICA)) for through the wall imaging (TWI) in which imaging is done using only one transmitting antenna. Numerical simulations are presented to illustrate the capabilities of our proposed method. We have used two dimensional finite difference time domain code in our simulations and TR-ICA is used for selective focusing on perfect electric conductor scatterers behind a wall. We have applied the Green's function of the layered medium for a wall with typical parameters.

In this study, a truncated singular value decomposition (TSVD) based computationally efficient through the wall imaging (TWI) is addressed. Mainly, two different scenarios with identical and non-identical multiple scatterers behind the wall have been considered. The scattered data are processed with special scheme in order to improve quality of the results and measurements are performed at four different frequencies. Next, effects of selecting truncation threshold in TSVD methods are analyzed and a detailed quantitative comparison is provided to demonstrate capabilities of these TSVD methods over selection of truncation threshold.

Art. 6374334

This paper presents a novel shape recognition approach for analysis of through wall images. The developed algorithm consists of image formation, processing for image enhancement, feature extraction and shape recognition. In this paper, ultra wideband step frequency continuous wave (SFCW) radar is used to collect C-scan data from which images are obtained to give the approximate shapes of target. Results on experimental data show that the proposed algorithm exhibits promising performances both in terms of target detection and recognition.

As the extent of the shortage becomes clear, an interagency task force is giving scientific users priority, but some say the material is not available at any price.

This paper describes a new patent-pending digital-ultrasonic sensor network technology, which provides a “security protection sphere” around the authorized user(s) and the infrastructure system or system(s) to achieve C3I in Homeland Security and Law Enforcement Applications. If the system device, such as a firearm, a secure computer, PDA, or vehicle is misplaced, stolen or removed from the security protective sphere, an alarm is activated. A digital-ultrasonic sensor/tag utilizes the system’s physical structure to form a 2 to 20 Meter programmable protection sphere around the device and the authorized user. In addition, the system allows only authorized users to utilize the system, thereby creating personalized weapons, secure vehicle access or secure computer hardware. If an unauthorized individual accesses the system device, the system becomes inoperative and an alarm is activated. As the command and control, the authorized individual is provided a secure wristwatch/PDA. Access control is provided by touch and is controlled through the wristwatch/PDA/smartcard with a unique digital-ultrasonic coding and matching protocol that provides a very high level of security for each wireless sensor.

Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance) Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS). Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.

Rapid standoff spectroscopic characterization of plastic waste using quartz tuning fork

Encryption is the primary solution to provide security to the data, which is travelling on a communication link between any pair of nodes, but Partial encryption is a technique to save computational power, overhead, speed, time and to provide quick security by only encrypting a selected portion of a bit stream. Securing the visual and multimedia data like images requires specific design consideration for use in different applications. The focus of this paper is on selecting the important part of the image that can efficiently achieve by conceptually selecting the part of the image which is further used in its normal mode of operation for encryption. Once encryption is done, the encrypted data is sent along with remaining original part of the message, ensuring its secured transmission and distribution over public networks. This paper proposes a partial image encryption using Single Bit Manipulation technique, convert each byte/character of the message to be encrypted, to its binary equivalent. Now, length of password is considered for bit left shift. i.e., Number of bits to be shifted to left will be decided by the length of password. The issue in traditional cryptosystem in many different areas such as wireless networking, mobile phone services and applications in homeland security is energy consumption for encryption of the large volume visual data. So we are dealing with a partial encryption algorithm of images.

Detection of volatile organic compounds (VOCs) at trace level (parts per billion volume (ppbv) to parts per trillion (pptv)) has become an important research area because of demanding applications in homeland security, environmental monitoring, and noninvasive diagnosis of diseases. The analysis of trace VOCs challenges existing analytical instruments because their concentrations are beyond current instrument limits of detection. In this dissertation, we have investigated an innovative microreactor that is suitable for quantitative analysis of volatile carbonyl compounds in ambient air as well as in human exhaled breath. The approach is based on microreactor chips fabricated from four inch silicon wafers. The chips have thousands of micropillars in the microfluidic channels for uniformly distributing gaseous samples flowing through the microreactors. The surfaces of the micropillars are functionalized with a quaternary ammonium aminooxy salt 2-(aminooxy)-N,N,N-trimethylethanammonium (ATM) iodide for trapping trace ketones and aldehydes by means of oximation reactions. ATM adducts and unreacted ATM are eluted from the microreactor with less than 40µL of methanol and directly analyzed by nanoelectrospray Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS). Capture efficiencies of above 98% have been achieved for ketones and aldehydes. Carbonyl compounds at levels of 1 ppbv have been detected using the microreactor for capture. Ambient air samples from indoor and outdoor areas were collected using Tedlar bags, and analyzed using the microreactor and FTICR-MS. The analysis of air samples provides the reference for analysis of exhaled breath samples. Finally, exhaled breath samples from patients with untreated lung cancer (LC) patients, patients with benign pulmonary nodules and healthy volunteers (smokers and non-smokers) were collected and analyzed using the same method. The FTICR-MS spectra showed that the exhaled breath samples from LC patients have a unique pattern of VOCs, in comparison with healthy controls and patients with benign pulmonary nodules. 2-Butanone, hydroxy-acetaldehyde, 3-hydroxy-2-butanone, and 4-hydroxy-hexenal (4-HHE) were found to have significant higher concentrations for LC patients. A simple diagnosis method based on four elevated VOCs could easily discriminate lung cancer patients from healthy controls and patients with pulmonary nodules with 90.6% diagnosis sensitivity and 81.3% specificity.

Integrating wavelets with clustering and indexing for effective content-based image retrieval

The boron-coated straw (BCS) neutron detection technology has been proposed as an attractive 3He replacement solution in a series of applications in homeland security, neutron science, and safeguards. In order to improve the neutron detection efficiency of the BCS, while maintaining manufacturability, Proportional Technologies, Inc. is introducing a modified BCS with significant performance benefits. The proposed pie-like shape consists of any desired number of arc segments, and an equal number of septa walls, which are radially oriented, and extending a desired distance towards the center of the geometry. Each septum is essentially a segment of the wall that has been collapsed onto itself, resulting in a rigid surface, coated on both sides. The area coated on the septa is added to the area coated on the arc segments, thus offering a significant benefit in sensitivity. Compared to a round straw of the same diameter, the coated wall area of the proposed shape with 12 septa is 3 times larger, assuming the septa are equal in length to each of the arc segments. We present laboratory measurements with two prototype detectors that demonstrate stable operation, a neutron sensitivity that is nearly 3 times higher than that measured in a simple BCS with no septa walls, and adequate energy resolution to effectively discriminate against gamma rays.