Jürgen Sachs

UWB short-range radar sensing - The architecture of a baseband, pseudo-noise UWB radar sensor

The pioneers of radio science made their first trials of wireless information transmission and demonstrated localization of a steel vessel by radio waves more than 100 years ago. Back then, the world of radio frequencies was organized in a very simple way. The researchers could use any frequency band. There was no interference by others and no controlling government bodies. Since then, governmental authorities have established tight regulations that have split up the available frequency band into small partitions for exclusive use. This article discusses the architecture of a baseband, pseudo-noise UWB radar and gives some examples of applications

Remote vital sign detection for rescue, security, and medical care by ultra-wideband pseudo-noise radar

The vitality of a human being is closely connected to temporal variations of its body geometry. This is quite obvious in the case of walking. But also when resting, the motion of inner organs such as lung or heart causes geometric alterations which may be registered by high-resolution ultra-wideband radar. Since the radio waves radiated by such radars are absolutely harmless, they may be deployed for monitoring of resident activities helping to ensure health, safety, and well-being of aged or needy people. These waves may also penetrate most of building materials and snow which makes them useful to detect earthquake and avalanche survivors, too. The most challenging task is the registration of respiration activity of an unconscious person. The principle of breathing motion detection by radar is explained and the major handicaps as well as appropriate counter measures are discussed. The possible structure of a survivor and residential injury detection radar system is considered and some results from field trials are summarized.

Signal processing for through wall moving target tracking by M-sequence UWB radar

In this paper, through wall moving target tracking by UWB radar is described as a complex process with all required phases of radar signal processing. For particular phases of that process, i.e. for raw radar data preprocessing, background subtraction, detection, trace estimation, localization and tracking itself, the phase significance and its corresponding representative methods are outlined. The complete process is illustrated by the results of processing of real data acquired by M-sequence UWB radar.

Efficient and Fast Method of Wall Parameter Estimation by Using UWB Radar System

Precise SAR imaging of objects or detection of moving a person behind a wall with UWB radar or nondestructive testing of walls in civil engineering requires the knowledge of wall parameters like thickness and permittivity. Their use in the data processing produces more precise and realistic results. The measurement of the wall parameters is challenge in a real environment especially when there is access only from one side of the wall. In this paper, an effective and fast algorithm for wall parameters estimation that can be used in practice is presented. For that purpose the magnitudes and the time positions of reflections from inner and outer interfaces of the wall are extracted from the data. A new scanning method reduces drastically the clutter caused by objects in the measurement environment such as reflections from other walls, the ceiling, the floor and antenna crosstalk. The algorithm was tested on 13 different types of walls with different permittivity and thickness. A handheld M-sequence UWB radar with horn and circular antennas was used for data gathering. The proposed method is very robust and the error of the thickness estimation was less than 10% for most of walls. The whole measurement can be handled by one person. The wall parameter estimation runs in real time and is fully automated.

Physiological signatures monitored by ultra-wideband-radar validated by magnetic resonance imaging

To validate physiological signatures acquired by ultra-wideband (UWB)-radar, like breathing and cardiac deformation, we propose the comparison with simultaneously acquired in-vivo magnetic resonance imaging (MRI). In this way it can be evaluated how physiological signals from the thoracic wall and internal structures, e.g., the heart, monitored by UWB-radar correlate with the physiological reality displayed by MR-imaging.

Modified cross-correlation back projection for UWB imaging: numerical examples

The article presents a modification of cross-correlated back projection algorithm for UWB imaging. The modified algorithm has improved performance in a sense of better quality of reconstructed 2D or 3D images of the propagation environment. The performance of the new imaging algorithm is demonstrated on numerical examples.

Ultra wideband radar assembly kit

Ultra wideband sounding has been found to be suitable for a large number of applications in various areas. This results in a variety of different requirements concerning the measurement electronics. The article describes a conception of a measurement system, which provides for high flexibility in adapting performance to the actual need.

Trapped victim detection by pseudo-noise radar

Radar based detection of earthquake survivors exploits the modulation of the backscattered signal by body motions of the victim. The most challenging task is the detection of respiration activity of an unconscious person. The principle of breathing motion detection by radar is explained and the major handicaps as well as appropriate counter measures are discussed. The possible structure of a survivor detection radar system is considered and some results from field trials are summarized.

Real-Time MIMO Channel Sounder for Emulation of Distributed Ultrawideband Systems

This paper introduces an ultrawideband (UWB) channel sounding system. Its novel architecture allows real-time measurements of multiple time-variant radio propagation channels in different ultrawide frequency bands. Its architecture allows emulation of multiuser systems, sensor networks, localization systems, and distributed MIMO radar systems. The sounder uses a maximum length binary sequence (MLBS) excitation signal and correlation processing in the receiver. Its synchronous multichannel operation is supported by excellent timing stability and low power consumption of miniature size modules based upon custom integrated SiGe circuits. The paper describes the architecture, design, calibration, basic parameters, and application examples of the sounding system.

Design and Test of an Imaging System for UWB Breast Cancer Detection

Abstract Electromagnetic ultra-wideband (UWB) sensing and imaging provide perspectives for early-stage breast cancer detection. This paper deals with practical challenges of real measurements. We present an experimental setup for breast phantom trials based on M-sequence radar technology and short active dipole antennas. It combines short impulse responses, appropriate fidelity and very small antenna dimension and allows array construction with sufficient number of antennas around the breast. The basic approach and obtained imaging results are presented. Furthermore, in this extended paper version continuative development steps are described and measurement results reflecting specific performance aspects are discussed.