K. Schilling

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.

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.

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.

Integrated pseudo-noise device with network analyzer performance for UWB sensing and component test

Network analyzers are the standard RF measurement devices due to their precision, flexibility and the wide spectral band within they may be operated. They are applied for quite different measurement tasks ranging from device characterization via component testing to a multitude of sensing applications. The disadvantages of network analyzers are their size, weight, power consumption, device costs, and their limited capability to operate MiMo (multi input - multi output) measurements. The paper deals with an alternative device concept which promotes a performance comparable to network analyzers by avoiding their main drawbacks. Its key feature is the use of very wideband PN (pseudo-noise) codes instead of swept or stepped sine waves. These signals may be generated and captured by a simple and stable way. The paper introduces the working principle of the device and shows some recent implementations and application examples.

M-Sequence-Based Single-Chip UWB-Radar Sensor

The article deals with a fully monolithically integrated single-chip M-sequence-based UWB-radar sensor, its architecture, selected design aspects and first measurement results performed on wafer and with packaged IC modules. The discussed chip is equipped with one transmitter and two receivers. The IC was designed and manufactured in commercially available high-performance 0.25 μm SiGe BiCMOS technology (f t = 110 GHz). Due to the combination of fast digital and broadband analogue system blocks in one chip, special emphasis has been placed on the electrical isolation of these functional structures. The manufactured IC is enclosed in a low-cost QFN (quad flat-pack no-leads) package and mounted on a PCB permitting the creation of MIMO-sensor arrays by cascading a number of modules. In spite of its relatively high complexity, the sensor head features a compact design (chip size of 2 × 1 mm2, QFN package size 5 × 5 mm2) and moderate power consumption (below 1 W at −3 V supply). The assembled transceiver chip can handle signals in the frequency range from near DC up to 18 GHz. This leads to an impulse response (IRF) of FWHD ≈ 50 ps (full width at half duration).

Experimental active antenna measurement setup for UWB breast cancer detection

Imaging by microwave UWB radar represents a promising technique for early-stage breast cancer detection. We present an experimental measurement setup for breast phantom trials based on M-sequence radar technology and active small antennas (interfacial dipoles). This approach combines short impulse responses, sufficient fidelity and very small antenna dimensions and allows for array construction with an adequate number of antennas around the breast. The presented imaging results illustrate the performance of the method.

Integrated wideband reflectometer with on-line reference measurement capability

The aim of the paper is to show the novel integrated reflectometer designed for the wideband sensing in the arbitrary frequency band up to 9 GHz and beginning at the DC. The reflectometer utilizes pseudo noise (PN) based single chip transceiver with one transmitter and two wideband sub-sampling receivers including integrated directional couplers. The topology with the two monolithically realized receive channels allows on-line monitoring of the difference between the reference, i.e. well-known medium, and the medium under test (MUT). Simple experiment with moist and dry grain shows the early competence of the approach for the process or material monitoring purposes.

Remote heartbeat capturing of high yield cows by UWB radar

The paper reports from first trials of remote heartbeat and breathing monitoring of milk cows. An UWB M-sequence device is used as high-resolution short-range radar sensor. Breathing and heart motion could be detected and well separated by their rates as well as the depth of their origin.

Integrated dielectric spectrometer for wideband and highspeed measurements using pseudo-noise codes

The paper gives a short introduction into some system-theoretic aspects and features of dielectric measurements by periodic wideband signals. Based on these considerations, a related measurement concept will be presented which is well suited for both compact device implementation and monolithic integration. Some implementation examples are shown and first measurement results are presented.