Martin Kmec

Recent Advances and Applications of M-Sequence based Ultra-Wideband Sensors

Ultra-wideband (UWB) sensing is an upcoming technique to gather data from complex scenarios such as nature, industrial facilities, public or private environments, for medical applications, non-destructive testing and many more. Currently it is hard to estimate the full spread of future applications. The measurement approach traditionally used is based on stimulation of the test objects by either short sub-nanosecond impulses or sine waves which are stepped/swept over a wide spectral band. This paper deals with an alternative approach, which uses very wideband pseudo-noise binary signals such as M-sequences for example. Such devices have a very high time stability, enable high measurement speed and do not burden the test objects with high voltage peaks. Furthermore, the device concept promotes monolithic circuit integration in a low cost semi-conductor technology. In what follows, the basic device concept and some extensions will be considered as well as some selected applications will be discussed.

Liquid and moisture sensing by ultra-wideband pseudo-noise sequence signals

The use of ultra-wideband signals for moisture sensing by electromagnetic wave interaction provides more information on the material under test compared to single tone or narrowband approaches, regarding spatial and frequency dependent phenomena. Current activities to regulate the emission of electromagnetic waves in the spectral band up to 10 GHz for sensor applications open new perspectives for microwave moisture sensing. Therefore, improved and cost effective ultra-wideband measurement principles will become more and more interesting. The use of short pulses or swept sine waves are classic approaches to cover a large spectral band. However, this paper deals with some variants of an alternative method, which applies pseudo-random codes, namely M-sequences, to stimulate the test objects. The method permits monolithic integration of the RF-electronics in SiGe technology. The signal generation and data capturing are referred to a common stable single tone clock and they are controlled by steep trigger signals. This provides for very stable operation, which allows for measurements in both time and frequency domain. Two versions of an M-sequence approach will be considered and their functioning will be demonstrated by means of simple measurement examples.

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.

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.

High resolution non-destructive testing in civil engineering by ultra-wideband pseudo-noise approaches

Ultra-wideband sensing provides new and interesting options for testing and inspection in many different fields. The article will deal with some applications for civil engineering. The advantage of UWB-sensing is the good penetration of the sounding waves through the material under test and its high spatial resolution. A flexible UWB-sensor conception will be discussed. Its working principle is based on pseudo-random sounding waves. The examples considered shall indicate the device performance for quite different sensor tasks.

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.

60 GHz-Ultrawideband Real-Time Multi-Antenna Channel Sounding for Multi Giga-Bit/s Access

60 GHz technology has been proposed recently for multi-Giga-bit/s access within different application scenarios, e.g. in crowded multi-user public transportation (PT) environments. Hence, channel sounders that are used to investigate multipath propagation and multi-user access techniques including spatial diversity and beam-forming in time-variant shadowing environments require ultra-wideband (UWB) operation, multiple antennas, and real-time. This paper presents probably the first channel sounder architecture fulfilling these requirements. Moreover, an experimental study is described which is performed for planning purposes and deployment of 60 GHz WLAN/WPAN networks in PT scenarios. Coverage analysis based on different PHY channelization schemes, including multiple access point configurations and antennas is addressed for the Airbus 340 cabin. Additionally, distributions of time dispersion, coherent bandwidth, and Rice K-factor in the in-cabin coverage area are presented. Specifically, a brief analysis under dynamic channel conditions due to human activities is introduced. The suitability of the 60 GHz-UWB channels sounder for PT scenarios is demonstrated. Besides, some channel results for finding the most suitable system parameters for 60 GHz access deployment of in-flight-entertainment (IFE) systems are given.

Digital Ultra-Wideband-Sensor Electronics integrated in SiGe-Technology

Ultra-Wideband (UWB) sensors are of great interest for a vast number of different applications. Due to their bandwidth they provide a great deal of information about the objects under test compared to classical narrow band sensors. This improves the reliability of the measurement results and opens up new fields of application for electrical sensors. New UWB-electronics are introduced which provide the opportunity for large volume application of such sensors. Its bandwidth ranges from nearly zero to 5 GHz. The RF interface comprises of integrated digital circuits in SiGe technology. A Maximum Length Binary Sequence (MLBS) is used as transmit signal. At the receiver, fast track-and-hold and interleaved sampling is applied for data recording. The received signal is processed by a DSP. Excellent timing stability, low power consumption and miniature size support synchronous multi-channel operation which is a prerequisite to build sensor arrays.

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.