Using Ultra-wideband Research Articles

Detection of Heart Rate through a Wall Using UWB Impulse Radar.

Measuring the physiological functions of the human body in a noncontact manner through walls is useful for healthcare, security, and surveillance. And radar technology can be used for this purpose. In this paper, a new method for detecting the human heartbeat using ultra wideband (UWB) impulse radar, which has advantages of low power consumption and harmlessness to human body, is proposed. The heart rate is extracted by processing the radar signal in the time domain and then using a principal component analysis of the time series data to indicate the phase variations that are caused by heartbeats. The experimental results show that a highly accurate detection of heart rate is possible with this method.

Enhanced 3D localisation accuracy of body‐mounted miniature antennas using ultra‐wideband technology in line‐of‐sight scenarios

This study presents experimental investigations on high-precision localisation methods of body-worn miniature antennas using ultra-wideband (UWB) technology in line-of-sight conditions. Time of arrival data fusion and peak detection techniques are implemented to estimate the three-dimensional (3D) location of the transmitting tags in terms of x, y, z Cartesian coordinates. Several pseudo-dynamic experiments have been performed by moving the tag antenna in various directions and the precision with which these slight movements could be resolved has been presented. Some more complex localisation experiments have also been undertaken, which involved the tracking of two transmitter tags simultaneously. Excellent 3D localisation accuracy in the range of 1–4 cm has been achieved in various experiment settings. A novel approach for achieving subcentimetre 3D localisation accuracy from UWB technology has been proposed and demonstrated successfully. In this approach, the phase centre information of the antennas in a UWB localisation system is utilised in position estimation to drastically improve the accuracy of the localisation measurements to millimetre levels. By using this technique, the average localisation error has been reduced by 86, 31, and 72% for the x-, y-, and z-axis coordinates, respectively.

An UWB ranging method based on wavelet packet decomposition

In wireless sensor networks (WSNs), precise ranging or positioning using Ultra-Wideband (UWB) signal attracts a wide research interest. The advantages of non-coherent energy detection (ED) are low sampling rate and low complexity, but the traditional energy detection schemes only analyze UWB signal in time domain, so the ranging or positioning error is large. In this paper, a novel ranging method is proposed which analyzes UWB signal in joint time-frequency domain. In this method, wavelet packet decomposition (WPD) is used to get the energy distributions in different sub-bands, and then back propagation artificial neural network (BP-ANN) is utilized to establish the mapping relationship between energy distributions and transmission ranges. The simulation results show that the ranging error of the trained BP-ANN in this method is significantly less than the traditional ED methods.

Data Fusion for Indoor Mobile Robot Positioning Based on Tightly Coupled INS/UWB

This paper proposes a novel sensor fusion approach using Ultra Wide Band (UWB) wireless radio and an Inertial Navigation System (INS), which aims to reduce the accumulated error of low-cost Micro-Electromechanical Systems (MEMS) Inertial Navigation Systems used for real-time navigation and tracking of mobile robots in a closed environment. A tightly-coupled model of INS/UWB is established within the integrated positioning system. A two-dimensional kinematic model of the mobile robot based on kinematics analysis is then established, and an Auto-Regressive (AR) algorithm is used to establish third-order error equations of the gyroscope and the accelerometer. An Improved Adaptive Kalman Filter (IAKF) algorithm is proposed. The orthogonality judgment method of innovation is used to identify the “outliers”, and a covariance matching technique is introduced to judge the filter state. The simulation results show that the IAKF algorithm has a higher positioning accuracy than the KF algorithm and the UWB system. Finally, static and dynamic experiments are performed using an indoor experimental platform. The results show that the INS/UWB integrated navigation system can achieve a positioning accuracy of within 0·24 m, which meets the requirements for practical conditions and is superior to other independent subsystems.

Detection of breast cancer using ultra-wide band beamforming algorithm

This paper is based on the general principle of beamforming algorithm of array signal processing. It gives a kind of high precision adaptive time-domain beamforming algorithm, uses ultra-wide band (UWB) microwave signal as an emission source applied to the human body in early breast cancer detection. In this paper, we build a two-dimensional, semicircle breast tissue model, use numerical simulation with finite-difference time-domain (FDTD) method for detection. The result shows the superiority of beamforming algorithm compared with that of confocal imaging algorithms and beamforming algorithms, especially to the Capon beamforming algorithm.

An Effective Timing Synchronization Scheme for DHTR UWB Receivers

In performing short-distance, high-data-rate wireless communications using ultra-wideband (UWB) systems, it is necessary to reduce the average transmission power and ensure a fixed synchronization error between the transmitter and receiver ends. Furthermore, to reduce multipath interference, the UWB system should be sometimes implemented using a rake receiver. However, for such receivers, the delay time and attenuation loss over each transmitted route must be known in advance. In the present study, the complexity of rake receivers with a large number of “fingers” is reduced by means of a delay-hopped transmitted-reference (DHTR) scheme, in which the delayed signal is correlated with the original signal; thereby avoiding the need for a separate template signal. The synchronization performance of the proposed DHTR receiver is analyzed both theoretically and numerically. An effective timing synchronization scheme, designated as “parallel signal acquisition with shared looped delay-line” (PS-SLD), is then proposed. The simulation results show that for multipath environments with a single user, the proposed synchronization scheme achieves a higher detection probability and a lower normalized mean square error (MSE) than the traditional timing dirty templates (TDT) algorithm.

Microwave reflectivity analysis of bone mineral density using ultra wide band antenna

ABSTRACTIn this paper, an approach to analyze the bone mineral density (BMD) based on microwave reflectivity is presented The proposed method enables us to overcome the health risks associated with diagnostic techniques such as X‐rays for repeated study of the rate of mineralization in the case of fractures or de‐mineralization in the case of osteoporosis. The proposed method is used to demonstrate the application of microwaves for continuous observation of skull healing process during post‐cranial surgery period. The proposed technique can be a potential clinical model in future for extracting target characteristics such as bone deposition thickness and other cranial defects. Based on the conclusions of wideband measured data and signal processing techniques, we propose to design the Transceiver using ultra‐wideband (UWB) pulsed technology. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:21–26, 2017

A New Robust Vital Sign Detection in Complex Environments Using Ultrawideband Radar

In this paper, we present a new algorithm for detection of respiratory movement of a person behind an obstacle by using ultrawideband (UWB) impulse radar. In this scenario, the most significant sign of being alive is the respiratory motions, which is hidden in parameters of the returned signal. This signal, whose statistical characteristics are generally nonstationary, is mixed with both stationary and nonstationary clutters and white and colored noise. In this paper, in an analytical way, the returned signal has been addressed by the Fourier series model with time-varying coefficients, as a fitting model. Then, based on the unconditional orthonormal representation of band-limited signals, a minimum mean square error estimator is introduced to determine the time-varying coefficients of the Fourier series. Using the new representation of the Fourier coefficients, a new approach is suggested that enables us to extract parameters of the respiration in very low signal-to-noise-and-clutter ratio (SNCR) conditions in the presence of both stationary and nonstationary clutters. Getting the most out of the estimator, this approach alleviates the problems associated with clutters and noise, without resorting to match filtering. Hence, a robust and blind respiratory-motion detection (RMD) from stationary or nonstationary received signal is obtained. By experimental data, we demonstrate the applicability of the new approach for the respiratory detection using UWB impulse radar in different aspects.

SAGD Process Monitoring in Heavy Oil Reservoir Using UWB Radar Techniques

In this paper, practical considerations for steam assisted gravity drainage (SAGD) monitoring using ultra-wideband (UWB) radar are studied. The SAGD process and important factors to monitor its performance are discussed. Several experiments are conducted to evaluate the possibility of using UWB radar for SAGD process monitoring. All the experiments are carried out on a simplified laboratory prototype, which is a plateau of wet sand covered by dry sand to mimic the steamed area of the reservoir. The effect of the metal pipe on the pulse shape and propagation inside the reservoir is also experimentally studied. Additionally, a miniaturized Vivaldi antenna capable of radiating within oil-sand is designed, fabricated, and verified as a sensor for the radar monitoring system. Power budget and heterogeneity analysis of the heavy reservoir for different grades of Athabasca oil-sands are also studied. Results demonstrate the possibility of using UWB radar to detect and image the contour of the steamed area in the SAGD process. The information collected by the UWB radar can be used for optimizing steam injection to improve the usage of water and energy.

Narrowband Interference Mitigation in UWB Systems Utilizing Frequency Dependence of Null Formation in Array Antennas

The high precision ranging using ultra wideband (UWB) signals is expected for various applications. However, UWB requires mitigation of narrowband interference (NBI) from other wireless systems. There have been many studies of adaptive notch filters to cope with NBI at various frequencies. This paper proposes a novel NBI mitigation method which utilizes frequency dependence characteristics in array antennas. We use power inversion to direct nulls to large-power input, which realizes NBI only suppression with a small calculation cost. The results show that the proposed method can obtain lower bit error rate. The proposed method can cope with variously directional and multiple-frequency NBIs without a priori knowledge of the incident waves.

Multistep Information Fusion for Target Detection Using UWB Radar Sensor Network

In this paper, we propose a multistep information fusion scheme for target detection through foliage and wall, using ultrawideband (UWB) radar sensor networks. We apply an information theory to detect target with poor signal quality in dynamic forest-environment. This method is motivated by the fact that echoes from the stationary target that is obscured by foliage has strong random characteristics. This is resolved by three steps of information fusion. For the first step of information fusion, we use Kullback–Leibler divergence-based weighting and generated a modified histogram. In the second step, we use entropy- and mutual information-based information fusion. Finally, we use three different fusion methods: 1) Dempster and Shafer theory of evidence; 2) proportional conflict redistribution rule 5; and 3) Bayesian network for decision fusion. Results show that when echoes are in poor quality, accurate detection can be achieved by applying our method. To demonstrate that our algorithm could be applied to other scenarios, we apply it to sense-through-wall human detection using different UWB radars, and simulation results show that our approach works well.

Breast tumor detection using UWB circular-SAR tomographic microwave imaging.

This paper describes the possibility of detecting tumors in human breast using ultra-wideband (UWB) circular synthetic aperture radar (CSAR). CSAR is a subset of SAR which is a radar imaging technique using a circular data acquisition pattern. Tomographic image reconstruction is done using a time domain global back projection technique adapted to CSAR. Experiments are conducted on a breast phantoms made of pork fat emulating normal and cancerous conditions. Preliminary experimental results show that microwave imaging of a breast phantom using UWB-CSAR is a simple and low-cost method, efficiently capable of detecting the presence of tumors.

Ultrawideband Synthetic Aperture Radar for Respiratory Motion Detection

This paper describes a method for detecting human respiratory motion with respiration-rate estimation using ultrawideband (UWB) synthetic aperture radar (SAR). In addition, positions of the breathing humans can be spatially resolved. The coherence of the SAR data is used to derive the generalized coherence factor (GCF), the generalized incoherence factor (GICF), and the filter-bank-based GCF (FBGCF) for the detection and estimation. The coherence is decreased by motion of the image object, and the GCF and GICF are used to detect the position of the moving object. Furthermore, since the spectral shift of SAR data varies with motion, the FBGCF can be used to determine the respiration rate. The efficacy of the proposed method was tested by constructing a UWB SAR system with a 1.5-GHz center frequency and a 1-GHz bandwidth. Through-wall SAR data of objects with various motions were acquired and analyzed. Moving objects were successively detected with a spectral resolution of 0.1 Hz, and using the GICF achieved a rejection ratio of 38 dB between stationary and moving objects. These results indicate that the FBGCF can be used for respiration-rate estimation.

Multiperson Tracking With a Network of Ultrawideband Radar Sensors Based on Gaussian Mixture PHD Filters

In this paper, we investigate the use of Gaussian mixture probability hypothesis density filters for multiple person tracking using ultrawideband (UWB) radar sensors in an indoor environment. An experimental setup consisting of a network of UWB radar sensors and a computer is designed, and a new detection algorithm is proposed. The results of this experimental proof-of-concept study show that it is possible to accurately track multiple targets using a UWB radar sensor network in indoor environments based on the proposed approach.

Remote ultra-wideband tomography of nonlinear electronic components

The efficiency of using ultra-wideband (UWB) signals for nonlinear radar is investigated. In the case at hand, it is necessary to see, based on scattered field disturbances, whether nonlinear inclusions are present in the field of view. The solution suggested is to compare the shapes of UWB signals reflected from the probe area under two conditions: an additional generator irradiating the probe area by intense monochromatic radiation is switched on and off. If a nonlinear electronic component is present in the probe area, the reflected UWB signals differ in shape. Thus, the difference in the shapes of the signals indicates the presence of a component with a nonlinear characteristic.

Ultra‐wideband radar‐based accurate motion measuring: human body landmark detection and tracking with biomechanical constraints

The authors propose and investigate a methodology for accurate human motion measuring by detecting and tracking human body landmarks using ultra-wideband (UWB) radars. The proposed method can estimate the markers’ positions and velocities in a two-dimensional space based on range measurements from a single radar given a prior information about the markers’ initial states. The detection of multiple human body landmarks is achieved by moving target indication and a new out-of-band constant false alarm rate detection, and the multiple landmark tracking is accomplished by a novel iterative convex optimisation-based approach with considerations of biomechanical constraints. The data association technique is then applied to validate and relate the detection results to target landmarks for generating range measurements, which are used for a convex optimisation-based sequential estimation algorithm to estimate the accurate marker locations. It is noted that the proposed optimisation-based sequential estimation is able to incorporate biomechanical constraints. In the field experiments, two radio frequency reflectors are attached to the wrist and the elbow of one human arm. It is demonstrated that detection and tracking of the moving trajectories of two markers are successfully achieved, and thus, the human arm motion is accurately measured using one UWB radar.

An ultra-wide-angle wireless camera using ultra wide band communication

A wide-angle wireless camera package using ultra wide band (UWB) communication is demonstrated in this paper. The camera is composed of a camera unit, camera processor module, UWB communication module, and power supply unit. A 162-degree lens module is developed to implement the ultra-wide-angle camera unit. All units are closely packed in a package tube with the size of ∼2 × 2 × 7 cm³ excluding an antenna. Measurements show that the camera package can transmit a high resolution video with the resolution of 2048 × 1536 (QXGA) at the frame rate of 15 fps in a MJPEG (Motion JPEG) compression mode. The camera has the maximum data transfer rate of ∼42 Mbps. The proposed camera can support ∼3X higher resolution and ∼5X higher data transfer rate than a commercial high-performance wireless camera. To the best of author's knowledge, this is the most compact wireless camera using UWB communication.

Information Spatial Focusing Scheme for UWB Wireless Communications in Smart Environments

This letter presents an information spatial focusing method for future smart environments using ultrawideband (UWB) wireless communications. This method allows to send high-data-rate information at predetermined specific spatial positions without localizing users, thereby protecting their privacy. The proposed approach is a combination of simplified UWB beamforming and signal processing. Compared to classical UWB beamforming, the proposed method exhibits greater information focusing capabilities by increasing greatly the peak-to-floor ratio between main and side beams.

Human Respiration Localization Method Using UWB Linear Antenna Array

Human respiration is the basic vital sign in remote monitoring. There has been remarkable progress in this area, but some challenges still remain to obtain the angle-of-arrival (AOA) and distinguish the individual signals. This paper presents a 2D noncontact human respiration localization method using Ultra-Wideband (UWB) 1D linear antenna array. The imaging reconstruction based on beamforming is used to estimate the AOA of the human chest. The distance-slow time 2D matrix at the estimated AOA is processed to obtain the distance and respiration frequency of the vital sign. The proposed method can be used to isolate signals from individual targets when more than one human object is located in the surveillance space. The feasibility of the proposed method is demonstrated via the simulation and experiment results.

Indoor Ultra-Wide Band Network Adjustment using Maximum Likelihood Estimation

Abstract. This study is the part of our ongoing research on using ultra-wide band (UWB) technology for navigation at the Ohio State University. Our tests have indicated that the UWB two-way time-of-flight ranges under indoor circumstances follow a Gaussian mixture distribution that may be caused by the incompleteness of the functional model. In this case, to adjust the UWB network from the observed ranges, the maximum likelihood estimation (MLE) may provide a better solution for the node coordinates than the widely-used least squares approach. The prerequisite of the maximum likelihood method is to know the probability density functions. The 30 Hz sampling rate of the UWB sensors enables to estimate these functions between each node from the samples in static positioning mode. In order to prove the MLE hypothesis, an UWB network has been established in a multi-path density environment for test data acquisition. The least squares and maximum likelihood coordinate solutions are determined and compared, and the results indicate that better accuracy can be achieved with maximum likelihood estimation.