Mária Švecová

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.

Through-the-wall localization of a moving target by two independent ultra wideband (UWB) radar systems.

In the case of through-the-wall localization of moving targets by ultra wideband (UWB) radars, there are applications in which handheld sensors equipped only with one transmitting and two receiving antennas are applied. Sometimes, the radar using such a small antenna array is not able to localize the target with the required accuracy. With a view to improve through-the-wall target localization, cooperative positioning based on a fusion of data retrieved from two independent radar systems can be used. In this paper, the novel method of the cooperative localization referred to as joining intersections of the ellipses is introduced. This method is based on a geometrical interpretation of target localization where the target position is estimated using a properly created cluster of the ellipse intersections representing potential positions of the target. The performance of the proposed method is compared with the direct calculation method and two alternative methods of cooperative localization using data obtained by measurements with the M-sequence UWB radars. The direct calculation method is applied for the target localization by particular radar systems. As alternative methods of cooperative localization, the arithmetic average of the target coordinates estimated by two single independent UWB radars and the Taylor series method is considered.

Object localization using round trip propagation time measurements

The object localization belongs to the basic tasks solved within wireless sensor networks (WSN). It can be shown, that for WSN based on UWB radar systems, localization methods using round trip propagation times can be used with advantages [1]. In this paper we introduce three localization methods of that kind, i.e., a direct calculation, a conventional and weighted least-squares methods and a Taylor series method. It is expected, that these methods can be applied especially for UWB WSN. The properties of the proposed methods will be illustrated by using computer simulations. It will be shown, that Taylor series method can provide the best estimate of object location.

Through Wall Tracking of Moving Targets by M-Sequence UWB Radar

In this paper different CFAR detectors for detection of multiple targets for UWB radar system will be described. In this paper, the cell averaging CFAR (CA-CFAR) cell averaging with greatest of (CAGO-CFAR) and ordered statistics CFAR (OS-CFAR) will be represented. The detectors outputs will be illustrated and compared. The properties of all detectors will be illustrated by real radar signal processing obtained by the measurement with the M-sequence UWB radar.

Target localization by a multistatic UWB radar

Moving target localization and tracking are of great interest for rescue, surveillance and security operations. The radar signal processing procedure providing the target position estimation consists of such phases of signal processing as raw radar data pre-processing, background subtraction, detection, time of arrival estimation, localization and tracking. In this paper, we will focus on the localization phase where we assume that for the target localization UWB radar equipped by one transmitting and N receiving antennas is used. Following this intention, the accuracy of the target localization provided by the least-squares method, the spherical-interpolation method and the Taylor series method applied within localization phase will be compared based on processing of radar signals obtained from real target tracking by UWB radar. The acquired results confirm that the Taylor series method can provide the best accuracy of the target positioning.

Imaging method: A strong tool for moving target tracking by a multistatic UWB radar system

In this paper, imaging method for moving target tracking by a multistatic ultra-wideband radar system is described. The task of moving target tracking consists in estimation of a target trajectory based on processing of raw radar data obtained from all receiving channels of a radar system. Then, the imaging method applied for target tracking consists of such signal processing phases as raw radar data pre-processing, background subtraction, fusion of the data obtained by receiving antennas of a radar, detection, localization and tracking itself. The performance of the imaging method described in this paper is demonstrated by signal processing obtained by M-sequence UWB radar for a scenario represented by through wall tracking of a single moving target. The obtained results confirm the excellent performance of the discussed method.

Multiple Person Localization Based on Their Vital Sign Detection Using UWB Sensor

In the past period, great efforts have been made to develop methods for through an obstacle detection of human vital signs such as breathing or heart beating. For that purpose, ultra-wideband (UWB) radars operating in the frequency band DC-5 GHz can be used as a proper tool. The basic principle of respiratory motion detection consists in the identification of radar signal components possessing a significant power in the frequency band 0.2–0.7 Hz (frequency band of human respiratory rate) corresponding to a constant bistatic range between the target and radar. To tackle the task of detecting respiratory motion, a variety of methods have been developed. However, the problem of person localization based on his or her respiratory motion detection has not been studied deeply. In order to fill this gap, an approach for multiple person localization based on the detection of their respiratory motion will be introduced in this chapter.

Target tracking algorithms for UWB radar network

Recently, it has been shown that UWB radar networks (UWB-RN) represent a strong tool for a short-range detection and localization of moving persons. In order to improve the accuracy of the target localization, a target tracking is usually implemented as the final phase of the radar signal processing. For the target tracking by a single UWB sensor, the linear Kalman filter is used frequently. On the other hand, in the case of UWB-RN, a target tracking can be implemented simultaneously within several nodes. Moreover, it can be combined with point-to-track and track-to-track association algorithms. In this paper, three algorithms of the target tracking by UWB-RN with a centralized architecture are introduced and compared. The proposed algorithms consist of two steps. Firstly, a standard tracking algorithm is used within multiple target tracking algorithm implemented in the basic nodes of UWB-RN. For that purpose, the linear Kalman filter, the modified gain Kalman filter and the H-infinity a posteriori filter will be considered. Then, a track-to-track association and multiple track fusion are implemented in the central node of UWB-RN. The proposed approach of the target tracking has been analyzed for through-the-wall multiple target tracking by two-node UWB-RN. The obtained results indicate that the application of the modified gain Kalman filter overcomes the performance of the other tested algorithms.

Real-time wireless UWB sensor network for person monitoring

Ultra-wide band (UWB) radar is a very perspective technology for short-range localization and tracking of moving persons. UWB radar sensor network (UWB-SN) employing the centralized data fusion method can significantly improve tracking capabilities of more people in complex building environments. In this paper we present real-time performing wireless UWB-SN hardware demonstrator. Its sensor nodes use M-sequence UWB radars front-end and low-cost ARM based quad-core microcomputer (ARM-MC) as a main signal processing block. The ARM-MC based on Raspberry Pi provides processing power for the preprocessing of received raw radar signals, algorithms for detection and estimation of targets coordinates, and finally compression of data sent to the data fusion center. Low-rate data streams (3600–6000 bits/s/node) of compressed target coordinates are sent from each sensor node to the data fusion center in the central node by using RF transceivers with integrated ARM microcontroller. The proposed UWB-SN uses wireless RF communication by using FSK modulation in free short range devices (SRD) 868–870 MHz frequency band concurrently with operation of the UWB radar front-end. Experimental testing confirmed real-time performance of developed UWB-SN hardware and acceptable precision of software algorithms implemented in 32-bit arithmetic. The introduced modular architecture of UWB-SN can be used for fast development and testing of new real-time people tracking applications.

TOA complementing method for target localization by UWB radar systems

Detection, localization and tracking of moving persons by using UWB radars still attract the attention of researchers and final users as well. The problem of UWB sensors usage for this application consists in the fact, that a single sensor is not very often able to localize a target through complex environment with the required reliability and accuracy. Therefore, UWB sensor network has been proposed for such applications. In this paper, we are dealing with the through-the-wall localization of a moving person by using the small sensor network consisting of two UWB radar systems. For that scenario, we have introduced a new method of the cooperative localization denoted as the time of arrival completing method (TOACOM). The performance properties of this method have been analyzed and compared in a real single target through-the-wall scenario with the direct calculation method based on a single radar application and with the method of joining intersections of the ellipses. The obtained results indicate the superior performance of TOACOM in comparison with the mentioned alternative approaches.