Ultra Wide Band signature analysis for detection of weapons & explosives

Lead Research Organisation: University of Birmingham
Department Name: Electronic, Electrical and Computer Eng

Abstract

This project will look at an important gap in the protection against terrorism: the ability to spot weapons & explosives (CW&E) that are hidden on a person's body (e.g. a 'suicide bomber'), and to detect them, especially at a distance. The project will carry out a study of using ultra wideband (UWB) sensors. These sensors are a portable piece of equipment which radiates an extremely short radio pulse. The project will introduce how to design such a sensor and what its performance will be like. The goal of the project is to design a system which can perform better than any other system, and which isn't too expensive. Eventually it is hoped that a system will be designed that can detect hidden weapons and explosives in an open area, without having to channel people through a narrow space.A UWB sensor is not a brand new system, but scientists from the University of Birmingham have thought of a new way of using them based on a concept called, late-time response (LTR) analysis . LTR is based on a principle of physics which is not very well known. The LTR of any object can produce a model which directly depends on the objects' shape and electrical properties. That means that particular targets have particular signatures , which identify them, just as we all have our own signature when we sign our name; and it is this signature which the project uses. In terms of using it to improve security however, the use of LTR may be a world first. The project hopes to establish the possibility of building a product which can detect hidden weapons and explosives. The results of the project will include theoretical and experimental data. Of course there are limitations to the technology, and in the project these need to be decided, especially if a product is going to be made which can be sold, and the eventual aim of the project is to use the technology to produce commercial products. There are a number of areas which may be interested in this product and these include: Airport security systems, b) Hidden security in public open spaces (e.g. Shopping Malls), c) Security at Government or Industrial sites, d) Baggage screening. During the project, interested users will be invited to discuss their needs for this product, making it as relevant as possible. It is not intended to produce a prototype system as part of the project, but the possibility of the essential elements will be demonstrated. The technology may be used with other technologies. For example, the system could be used to select suspected persons for further scanning using high frequency (Terahertz) imaging, to obtain more details. In some areas the product developed in this project may be a lot cheaper than equipment which is already used, for example in airports, where scanning equipment can cost around 100 thousand pounds; the technology in this project should be able to offer a cheaper solution. As well as airport screening, other security products could also be developed: e.g. protecting public spaces, aiding drugs investigation. There are also likely to be benefits into other areas, e.g. military equipment to help with peacekeeping tasks. However, the project offers not only commercial benefits. Throughout the project, it is intended that research papers will be published which will help scientists understand this new technology, improving scientific understanding of the late response principle. But perhaps the most important aspect of this project will be to help prevent terrorist attacks, which is the biggest benefit of all, and whose value cannot be counted.
 
Description Two experimental systems (time (TD) and frequency domain (FD)) were built and tested for the concealed weapon detection at a stand off distance (~10 m).

Novel calibration procedure for refinement of the useful LTR part of the signal has been suggested. The procedure is based on UWB system hardware ring suppression by linear and non-linear adaptive filtering.

This approach has been successfully demonstrated on measured signals from reference targets. It was validated that further reduction of signal distortion could be achieved both through improvement of experimental hardware and improvement in signal processing techniques. The first is achieved by using low noise pulse system components, in particular, pulse amplifiers and antennas with suppressed ring, producing minimal pulse distortion in the TD. Further development of the processing algorithm is envisaged to be in the field of equalization of nonlinear distortion, which can be caused by some nonlinear parts of RF components.

An utilization of early-time-responce ( ETR) has been considered as an additional tool enable detection and multitarget resolution. It was developed the approach based on combined target detection by both LTR, delivering recognition by unique signature, and ETR, defining a localization and composition of complex target, for enhanced target detection.

Generic study of UWB EM waves interaction (reflections) with pair: human body - weapon has been provided and most suitable techniques for the information extraction from the reflected signal have been investigated.

Algorithms were developed to extract target signature based on the postulated late response signal. In particular, the Matrix Pencil of Functions algorithm was shown to compute signatures which allowed the measured signal to be accurately regenerated. However, the signature produced was sensitive to noise and increasing target complexity. In particular, it was not possible to measure a useful target signature in the presence of a human body.

Pulse response analysis of human-weapon reflection in both time and frequency domain give clear indication on presence or absence of an isolated hidden weapon.

The system built at these principles can be used presumably as an alerting system and an appropriate vigorous analysis should be undertaken against a suspicion person by means of other technology.

High level of false alarms in the system occurs due to a human body variation during the analysis and reflection from objects outside the human body but within the same resolution cell.

Relatively low level of false alarms observed only when an appropriate weapon positioned on the body side directly illuminated by the radar and presumably two spatially separated systems should be used to improve the correct detection at a reasonable false alarm level.

The main unsolved problem is how to develop a reasonably compact antenna (presumably array) covering the discussed frequency range and having relatively narrow beam width (illuminate only one human at a time).

To resolve the problem must be developed UWB radiating element. The array should be developed as MIMO system to minimise the array cost and dimension.

it has been used for proposal of research on human body EM propagation medium for healthcare (Subject for EPSRC project submission)
Exploitation Route The main benefit TRT see from the project is the development of a prototype people tracking radar system, allowing real-time demonstration of a radar capability with the following features:

• Instantaneous measurement of range, range-rate and angle for moving people

• Detection of stationary people (by breathing motion) with measurement of range and angle

• Operation (at a reduced range) through walls

• Providing area surveillance, locating people to sub-metre accuracy, by fusing outputs of multiple radars

The main benefits UoB see from the project are:

• Package of EM modelling, equipment control and signal processing for analysis of UWB backscattered signal software has been developed and now is in use as a computer tool for research and commercial purposes.

• Brand new Bistatic (Forward Scattering) UWB radar has been suggested for difficult target detection;

Some work carried out in this project has also benefited the UWB3D project (TP/CHBT/007/00022) which appears to offer a more promising approach to concealed weapon detection.
TRT have held meetings and discussions with potential users of the equipment (including Home Office Scientific Development Branch and BAA) and gained a better understanding of user needs. Discussions with other interested parties (e.g. other Thales companies are continuing). The insight and contacts gained are of value to other developments, in particular, the 3D UWB imaging radar developed with TSB support in the UWB3D project (TP/CHBT/007/00017).

UoB has held a number of meetings with MoD related companies to discuss of value to other development such as a bistatic UWB radar for target detection in complex environment and prelimnary arrangement for UWB research continuation for Homeland Security application has been made with SELEX Galileo.
 
Description Thales Research Ltd 
Organisation Thales Group
Department Thales Research & Technology (Uk) Ltd
Country United Kingdom 
Sector Private 
Start Year 2006