Ultra-wide Band (UWB) technology is a new, useful and safe technology in the fleld of wireless body networks. This paper focuses on the feasibility of estimating vital signs | speciflcally breathing rate and heartbeat frequency | from the spectrum of recorded waveforms, using an impulse-radio (IR) UWB radar. To this end, an analytical model is developed to perform and interpret the spectral analysis. Both the harmonics and the intermodulation between respiration and heart signals are addressed. Simulations have been performed to demonstrate how they afiect the detection of vital signs and also to analyze the in∞uence of the pulse waveform. A fllter to cancel out breathing harmonics is also proposed to improve heart rate detection. The results of the experiments are presented under difierent scenarios which demonstrate the accuracy of the proposed technique for determining respiration and heartbeat rates. It has been shown that an IR-UWB radar can meet the requirements of typical biomedical applications such as non-invasive heart and respiration rate monitoring.

/pdf/analysis-of-vital-signs-monitoring-using-an-ir-uwb-radar-3dvli0yol5.pdf

Analysis of vital signs monitoring using an ir-uwb radar

Ultrawideband (UWB) radar technology has emerged as one of the preferred choices for through-wall detection due to its high range resolution and good penetration. The resolution is a result of high bandwidth of UWB radar and helpful for better separation of multiple targets in complex environment. Detection of human targets through a wall is interesting in many applications. One significant characteristic of human is the periodic motion, such as breathing and limb movement. In this letter, we apply the UWB radar system in through-wall human detection and present the methods based on fast Fourier transform and S transform to detect and identify the human's life characteristic. In particular, we can extract the center frequencies of life signals and locate the position of human targets from experimental data with high accuracy. Compared with other research studies in through-wall detection, this letter is concentrated in the processing and identifying of the life signal under strong clutter. It has a high signal-to-noise ratio and simpler to implement in complex environment detection. We can use the method to search and locate the survivor trapped under the building debris during earthquake, explosion, or fire.

Through-Wall Detection of Human Being's Movement by UWB Radar

This paper focuses on the feasibility of tracking the chest wall movement of a human subject during respiration from the waveforms recorded using an impulse-radio (IR) ultra-wideband radar. The paper describes the signal processing to estimate sleep apnea detection and breathing rate. Some techniques to solve several problems in these types of measurements, such as the clutter suppression, body movement and body orientation detection are described. Clutter suppression is achieved using a moving averaging filter to dynamically estimate it. The artifacts caused by body movements are removed using a threshold method before analyzing the breathing signal. The motion is detected using the time delay that maximizes the received signal after a clutter removing algorithm is applied. The periods in which the standard deviations of the time delay exceed a threshold are considered macro-movements and they are neglected. The sleep apnea intervals are detected when the breathing signal is below a threshold. The breathing rate is determined from the robust spectrum estimation based on Lomb periodogram algorithm. On the other hand the breathing signal amplitude depends on the body orientation respect to the antennas, and this could be a problem. In this case, in order to maximize the signal-to-noise ratio, multiple sensors are proposed to ensure that the backscattered signal can be detected by at least one sensor, regardless of the direction the human subject is facing. The feasibility of the system is compared with signals recorded by a microphone.

https://www.mdpi.com/1424-8220/14/2/2595/pdf

Techniques for Clutter Suppression in the Presence of Body Movements during the Detection of Respiratory Activity through UWB Radars

This paper presents the design and prototype of a wireless health monitoring system using mobile phone accessories. We focus on measuring real-time electrocardiogram (ECG) and heart rate monitoring using a smartphone case. With the increasing number of cardiac patients worldwide, this design can be used for early detection of heart diseases. Unlike most of the existing methods that use an optical sensor to monitor heart rate, our approach is to measure real-time ECG with dry electrodes placed on smartphone case. The collected ECG signal can be stored and analyzed in real time through a smartphone application for prognosis and diagnosis. The proposed hardware system consists of a single chip microcontroller (RFduino) embedded with Bluetooth low energy, hence miniaturizing the size and prolonging battery life. The system called “smart case” has been tested in a laboratory environment. We also designed a 3-D printed smartphone case to validate the feasibly of the system. The results demonstrated that the proposed system could be comparable to medical grade devices.

A Wireless Health Monitoring System Using Mobile Phone Accessories

In this paper, an innovative strategy for the passive localization of transceiver-free objects is presented. The localization is yielded by processing the received signal strength data measured in an infrastructured environment. The problem is reformulated in terms of an inverse source one, where the probability map of the presence of an equivalent source modeling the moving target is looked for. Toward this end, a customized classification procedure based on a support vector machine is exploited. Selected, but representative, experimental results are reported to assess the feasibility of the proposed approach and to show the potentialities and applicability of this passive and unsupervised technique. “(c) Institute of Physics”

/pdf/electromagnetic-passive-localization-and-tracking-of-moving-20rmp7n31j.pdf

Electromagnetic passive localization and tracking of moving targets in a WSN-infrastructured environment

The radar capable to detect and perform diagnostics of a state of the human being behind obstacles and in conditions of bad visibility could be used for the manifold applications. The potential consumers of the radar are: rescue services, antiterrorist detachments and law-enforcement bodies. It is possible also to use this device in medicine. In this paper, the experiments with using of continuouswave subsurface radar are described. The recorded oscillograms and their frequency spectrums for heartbeat, respiration and articulation of a man, which is taking place behind an obstacle (wall), are presented.

/pdf/detection-of-human-breathing-and-heartbeat-by-remote-radar-1efh4r5qmj.pdf

Detection of Human Breathing and Heartbeat by Remote Radar

A radar for detecting and testing health condition of an individual, who is separated from the radar by a non-metal wall or in poor visibility, could be useful in many critical services such as medicine, rescue service, law and antiterrorists enforcements In this paper, we describe the theoretical approach and experiments utilizing a continuous-wave subsurface radar. New theoretical results, experimental records and their frequency spectrums for heartbeat, respiration and articulation of a man are presented.

Through wall sensing of human breathing and heart beating by monochromatic radar

The former Senate building, Saint-Petersburg, Russia is being refltted for using it by the Constitutional court of Russian Federation. The team of Remote Sensing Laboratory was invited to participate in this work. The case is that the under∞oor water heating system had been installed in the Senate building. The arrangement of pipes hasn't been precisely documented. Besides, there are power and communications cables as well as metal mesh under the concrete ∞oor of the building. Workers were afraid of damaging pipes and cables during laying the parquet ∞oor. Main purpose was to investigate the building ∞oor and to deflne exact position of pipes and cables with the help of subsurface holographic radars developed by Remote Sensing Laboratory. 1. INTRODUCTION The paper covers a possible use of holographic subsurface radars difierent from traditional impulse radars (1). They are distinguished by the type of frequency spectrum. The impulse radar has continuous frequency spectrum while the holographic radar has discrete one. Impulse radars have larger penetration depths because they have variable ampliflcation in the stroboscopic receiver. The signal re∞ected from deeper objects is amplifled more than the signal from shallow objects. This is the main advantage of impulse radars. The holographic radar has the same ampliflcation for all objects. In this case, the penetration depth depends on medium attenuation and its homogeneity at shallow depths. Shallow heterogeneities would shade deeper objects in recorded images. At shallow depths, the holographic radar has a distinct advantage in resolution over the impulse radar because the radar frequency range can be easily adapted to the demands of a particular task. Another extremely important advantage of this holographic radar technology is the possibility to image, without reverberation, dielectric materials that lie above a metal surface (2). Such materials cannot be efiectively inspected with traditional time-domain impulse radar technology. Reverberation of pulses between the radar antenna and shallow metal objects obscures the actual location and shape of these objects which are seen as multiple re∞ections (often called ghosts or phantoms) of the transmitted impulse signal on a relatively uniform background (3). Holographic radars could be easily adapted to the US Federal Communications Commission regulations and demands as the radar can use free frequency bands that don't interfere with other devices. Also, they are cheaper than impulse radars. 2. EXPERIMENTS

/pdf/an-example-of-holographic-radar-using-at-restoration-works-1e1deqrgje.pdf

An example of holographic radar using at restoration works of historical building

In this paper the mathematical models and results on processing the experimental single-frequency microwave holograms received by scanning subsurface radar with sine wave signal are submitted. The holograms reconstruction method with the use of support functions, which take into account the near field of the aperture antenna with round cylindrical waveguide, is analysed. The models consider both known and unknown phase shift of the signal reflected from the point object. It is theoretically and experimentally shown that single- frequency holograms reconstruction allows to estimate depth of shallowly buried objects and improve the resolution on the probing surface with the growth of objects depths.

Microwave hologram reconstruction for the RASCAN-type subsurface radar

In this paper we describe a method of minefield reconnaissance with the use of the multi-frequency ground-penetrating radar (GPR) combined with a metal detector. This method allows the mine images in the soil to be obtained in the band of the mine detector sensors. An experimental installation with remote control and scanning sensors has been designed and built. A mine detector of this kind can be used in peacekeeping and humanitarian operations.

http://www.rslab.ru/downloads/mines_gpr_2000.pdf

I. A. Vasilyev

Papers

Detection of Human Breathing and Heartbeat by Remote Radar

Through wall sensing of human breathing and heart beating by monochromatic radar

An example of holographic radar using at restoration works of historical building

Microwave hologram reconstruction for the RASCAN-type subsurface radar

Remote control mine-detection system with GPR and metal detector