Could Radar Be a More Cost-Effective Security Screening Alternative to X-Rays?

By: Damien Clarke
Lead Consultant

10th October 2019

5 minute read

Home » Technology

A key task in the security market is the detection of concealed threats, such as guns, knives and explosives. While explosives can be detected by their chemical constituents the other threats are defined by their shape. A threat detection system must, therefore, be able to produce an image of an object behind an opaque barrier.

X-rays are probably the most commonly known technology for achieving this and they are widely used for both security and medical applications. However, while they produce high-quality images, x-ray machines are not cheap and there are health concerns with their frequent use on or in the vicinity of people.

An alternative to x-rays often used at airports for full-body screening are microwave imaging systems. These allow the detection of concealed objects through clothes though the spatial resolution is relatively low and objects are often indistinguishable (hence the requirement for a manual search). The ability to detect and identify concealed items can, therefore, be improved by using a high-frequency mm-wave (60 GHz) system.

Plextek has investigated this approach through the use of a Texas Instruments IWR6843 60 – 64 GHz mm-wave radar which is a relatively inexpensive consumer component that could be customised to suit many applications. However, a single radar measurement only contains range information and not angle information. It is, therefore, necessary to collect multiple measurements of an object from different viewpoints to form an image. This is achieved through the use of a custom 2D translation stage that enables the radar to be automatically moved to any point in space relative to the target object. In this example, radar data was collected across a regular grid of 2D locations with millimetre spacing between measurements.

This large set of radar measurements can then be processed to form an image. This is achieved by analysing the small variations in the signal caused by the change in viewpoint when the object is measured from different positions. The set of range only measurements is then extended to include azimuth and elevation as well. In effect, this process produces a 3D cube of intensity values defining the radar reflectivity at each point in space. A slice through this cube at a range corresponding to the position of the box allows an image to be formed of an object that is behind an (optically) opaque surface.

In this case, a cardboard box containing a fake gun was used as the target object. Clearly, a visual inspection of this box would not reveal the contents, however, 60 GHz mm-waves can penetrate cardboard and therefore an image of the concealed object can be produced. In this case, the resulting image of the contents of the box clearly shows the shape of the concealed gun.

This example simulates the detection of a gun being sent through the post and automatic image analysis algorithms would presumably be capable of flagging this box for further inspection. This would remove the need for human involvement in the screening process for each parcel.

A more mature sensor system using this approach could be produced that did not require the manual scanning process but used an array of antenna instead. It would also be possible to produce similar custom systems that were optimised for different target sets and applications.

 

Acknowledgement

This work was performed by Ivan Saunders during his time as a Summer student at Plextek before completing his MPhys at the University of Exeter.

A key task in the security market is the detection of concealed threats, such as guns, knives and explosives. While explosives can be detected by their chemical constituents the other threats are defined by their shape. A threat detection system must, therefore, be able to produce an image of an object behind an opaque barrier.

X-rays are probably the most commonly known technology for achieving this and they are widely used for both security and medical applications. However, while they produce high-quality images, x-ray machines are not cheap and there are health concerns with their frequent use on or in the vicinity of people.

An alternative to x-rays often used at airports for full-body screening are microwave imaging systems. These allow the detection of concealed objects through clothes though the spatial resolution is relatively low and objects are often indistinguishable (hence the requirement for a manual search). The ability to detect and identify concealed items can, therefore, be improved by using a high-frequency mm-wave (60 GHz) system.

Plextek has investigated this approach through the use of a Texas Instruments IWR6843 60 – 64 GHz mm-wave radar which is a relatively inexpensive consumer component that could be customised to suit many applications. However, a single radar measurement only contains range information and not angle information. It is, therefore, necessary to collect multiple measurements of an object from different viewpoints to form an image. This is achieved through the use of a custom 2D translation stage that enables the radar to be automatically moved to any point in space relative to the target object. In this example, radar data was collected across a regular grid of 2D locations with millimetre spacing between measurements.

This large set of radar measurements can then be processed to form an image. This is achieved by analysing the small variations in the signal caused by the change in viewpoint when the object is measured from different positions. The set of range only measurements is then extended to include azimuth and elevation as well. In effect, this process produces a 3D cube of intensity values defining the radar reflectivity at each point in space. A slice through this cube at a range corresponding to the position of the box allows an image to be formed of an object that is behind an (optically) opaque surface.

In this case, a cardboard box containing a fake gun was used as the target object. Clearly, a visual inspection of this box would not reveal the contents, however, 60 GHz mm-waves can penetrate cardboard and therefore an image of the concealed object can be produced. In this case, the resulting image of the contents of the box clearly shows the shape of the concealed gun.

This example simulates the detection of a gun being sent through the post and automatic image analysis algorithms would presumably be capable of flagging this box for further inspection. This would remove the need for human involvement in the screening process for each parcel.

A more mature sensor system using this approach could be produced that did not require the manual scanning process but used an array of antenna instead. It would also be possible to produce similar custom systems that were optimised for different target sets and applications.

Acknowledgement

This work was performed by Ivan Saunders during his time as a Summer student at Plextek before completing his MPhys at the University of Exeter.

Further Reading

diversity in engineering, GCSE entries, UK engineering, A Levels engineering

Reasons to be Cheerful

Nicholas Hill, Plextek

By: Nicholas Hill
CEO

18th September 2019

3 minute read

Home » Technology

At a time when the media is particularly obsessed with gloomy speculation and bad news, it was great to hear not one but two good news stories for the UK engineering technology sector.

The first came out of the A-level and GCSE results that have been announced in recent weeks.  It seems that more girls than boys (50.3%) have taken A-levels for the first time.  This progress has been driven by years of campaigning by government, business, professional bodies and schools, influences like the appearance of female role models on TV and radio, and a move to a more practical-based curriculum.

Welcome News

As someone who is impatient to see an improvement in gender diversity in engineering, this is welcome news.  Digging a little deeper into the numbers does reveal an important issue though, which is that the overall science numbers are propped up by high levels of girls taking A-level biology.  If you look at the A-levels that lie at the core of many engineering disciplines, girls account for just 23% of physics intake and 39% of maths.  The attractiveness of physics in particular, essential for so much of engineering, has a long way to go before we reach anything like gender parity.

So the A-Level figures are perhaps better news for our burgeoning bio-tech sector than a typical engineering technology employer.  What is more encouraging for engineering is that the figures for GCSE entries show girls making up around 50% in all the three sciences – physics, chemistry and biology – and maths too.  That’s a great result, and it will be interesting to see how this GCSE cohort’s subject choices turn out at A-level.

A Practical Effect

EngineeringUK data shows that just 12% of those working in engineering are female, with the disparity being largely due to girls dropping out of the educational pipeline at every decision point, despite generally performing better than boys in STEM subjects at school.  We need to see continued, incremental forward progress, so it’s good to be able to actually see some.  Gender diversity matters not just because engineering will surely be in a better place when it is less male-dominated, but also from the purely practical effect it will have on increasing overall numbers in the talent pool.  As anyone running a UK company that needs to recruit professional engineers will tell you, we have been facing a desperate talent shortage for some years.

The other good news that caught my eye was record foreign investment in UK tech companies this year.  £5.5bn was invested in the first seven months of the year, which equates to a greater per capita amount than for the US tech sector – wow!

The UK leads Europe in inward investment, but is probably doing particularly well just now because of the weak pound and the US-China trade war, which has made those countries less attractive to foreign investors, many of which are from Asia.  This increase in investment in the tech sector is in spite of an overall reduction in UK foreign direct investment, and serves to show that the UK is still a force to be reckoned with in new technology and innovation.

Your Turn

I hope you enjoyed this brief respite from the doom and gloom stories.  If you’d like another diversion before going back to your newspaper, perhaps have a think about what else your organisation could do to promote engineering as a potentially attractive career option to girls and women, particularly those making implicit career choices through the subject choices they are making at A-level and university.

At a time when the media is particularly obsessed with gloomy speculation and bad news, it was great to hear not one but two good news stories for the UK engineering technology sector.

The first came out of the A-level and GCSE results that have been announced in recent weeks.  It seems that more girls than boys (50.3%) have taken A-levels for the first time.  This progress has been driven by years of campaigning by government, business, professional bodies and schools, influences like the appearance of female role models on TV and radio, and a move to a more practical-based curriculum.

Welcome News

As someone who is impatient to see an improvement in gender diversity in engineering, this is welcome news.  Digging a little deeper into the numbers does reveal an important issue though, which is that the overall science numbers are propped up by high levels of girls taking A-level biology.  If you look at the A-levels that lie at the core of many engineering disciplines, girls account for just 23% of physics intake and 39% of maths.  The attractiveness of physics in particular, essential for so much of engineering, has a long way to go before we reach anything like gender parity.

So the A-Level figures are perhaps better news for our burgeoning bio-tech sector than a typical engineering technology employer.  What is more encouraging for engineering is that the figures for GCSE entries show girls making up around 50% in all the three sciences – physics, chemistry and biology – and maths too.  That’s a great result, and it will be interesting to see how this GCSE cohort’s subject choices turn out at A-level.

A Practical Effect

EngineeringUK data shows that just 12% of those working in engineering are female, with the disparity being largely due to girls dropping out of the educational pipeline at every decision point, despite generally performing better than boys in STEM subjects at school.  We need to see continued, incremental forward progress, so it’s good to be able to actually see some.  Gender diversity matters not just because engineering will surely be in a better place when it is less male-dominated, but also from the purely practical effect it will have on increasing overall numbers in the talent pool.  As anyone running a UK company that needs to recruit professional engineers will tell you, we have been facing a desperate talent shortage for some years.

The other good news that caught my eye was record foreign investment in UK tech companies this year.  £5.5bn was invested in the first seven months of the year, which equates to a greater per capita amount than for the US tech sector – wow!

The UK leads Europe in inward investment, but is probably doing particularly well just now because of the weak pound and the US-China trade war, which has made those countries less attractive to foreign investors, many of which are from Asia.  This increase in investment in the tech sector is in spite of an overall reduction in UK foreign direct investment, and serves to show that the UK is still a force to be reckoned with in new technology and innovation.

Your Turn

I hope you enjoyed this brief respite from the doom and gloom stories.  If you’d like another diversion before going back to your newspaper, perhaps have a think about what else your organisation could do to promote engineering as a potentially attractive career option to girls and women, particularly those making implicit career choices through the subject choices they are making at A-level and university.

 

Further Reading

design, sustainability

Elegance and Sustainability

Steve FItz, Director Technology

By: Steve M.Fitz
Director, Technology

5th September 2019

3 minute read

Home » Technology

There is a grandfather clock in my house that is nearly 200 years old – it has been in the family for a long time. Its face is lined and the body is a bit shabby (rather like its owner I hear you say) but it keeps good time and announces itself on the hour with a musical bong. Once a week I lift the 7 kg weights approximately 1m to make sure that it continues for the next 7 days. That energy input is equivalent to about one-quarter of the capacity of an AA cell; an impressive exercise in low power design given the amount of ticking and bonging that goes on in a week. In its 200 year life, it would have used about 2400 batteries if that was how it was powered.

Were it to break we would have to get it fixed because it is impossible to contemplate destroying something with such dignity. Luckily the designer had in mind the ability to repair so it has been patched and bodged over the years. If it ever finally comes to the end of its life however, every part of it could be recycled: the wood, the brass the lead weights. In fact, it could be reborn as a whole new clock.

Designing for a changing world

I have been thinking about this clock and the lessons it can teach us in designing future products that face up to the implications of climate change.

Form: Most of the products that we use are so ugly that we cannot wait to sling them the minute their function is superseded by the next model. They have no personality or vitality, they are just there to do a job and we have no emotional attachment to them at all. Looking at it more positively, if a product is to be designed to have a long life it will have to be sufficiently elegant for us to want to have it around for that long. Something that is old (or at least not current) will have to get cool; people who carry around and use stuff that is not the latest will themselves have to get cool. It has happened in the past and it needs to happen now.

Function: The clock is quite demanding. It needs winding weekly and putting right occasionally; wouldn’t it be better to have it powered by electricity and set by radio waves? – wouldn’t that improve the ‘user experience’? Definitely not. One of the attractive things about the clock is its dependence on me to wind it; we have bonded, I and the clock are one machine.

So some questions to ask when designing our next product: How can I make this last 200 years? How can I make this so elegant that someone wants it to last 200 years? How can I make this completely recyclable, even if that means making it more demanding of the user?

There is a grandfather clock in my house that is nearly 200 years old – it has been in the family for a long time. Its face is lined and the body is a bit shabby (rather like its owner I hear you say) but it keeps good time and announces itself on the hour with a musical bong. Once a week I lift the 7 kg weights approximately 1m to make sure that it continues for the next 7 days. That energy input is equivalent to about one-quarter of the capacity of an AA cell; an impressive exercise in low power design given the amount of ticking and bonging that goes on in a week. In its 200 year life, it would have used about 2400 batteries if that was how it was powered.

Were it to break we would have to get it fixed because it is impossible to contemplate destroying something with such dignity. Luckily the designer had in mind the ability to repair so it has been patched and bodged over the years. If it ever finally comes to the end of its life however, every part of it could be recycled: the wood, the brass the lead weights. In fact, it could be reborn as a whole new clock.

Designing for a changing world

I have been thinking about this clock and the lessons it can teach us in designing future products that face up to the implications of climate change.

Form: Most of the products that we use are so ugly that we cannot wait to sling them the minute their function is superseded by the next model. They have no personality or vitality, they are just there to do a job and we have no emotional attachment to them at all. Looking at it more positively, if a product is to be designed to have a long life it will have to be sufficiently elegant for us to want to have it around for that long. Something that is old (or at least not current) will have to get cool; people who carry around and use stuff that is not the latest will themselves have to get cool. It has happened in the past and it needs to happen now.

Function: The clock is quite demanding. It needs winding weekly and putting right occasionally; wouldn’t it be better to have it powered by electricity and set by radio waves? – wouldn’t that improve the ‘user experience’? Definitely not. One of the attractive things about the clock is its dependence on me to wind it; we have bonded, I and the clock are one machine.

So some questions to ask when designing our next product: How can I make this last 200 years? How can I make this so elegant that someone wants it to last 200 years? How can I make this completely recyclable, even if that means making it more demanding of the user?

Further Reading

Nigel Whittle, Head of Medical & Healthcare, features in ADS Advance this week.

Soldiers on the battlefield are prone to all kinds of injuries. Some of the most common include musculoskeletal injuries, environmental injury and hearing damage. Now, the government is funding projects that could see soldiers utilise wearable tech to flag potential injuries before they occur.

To read the full article click here.

Henry Wadsworth, Project Engineer, features in IoT Global Network this week.

With the predictions of billions of devices connected to the Internet of Things (IoT), the idea of having to change all the batteries is a logistical, practical and financial nightmare. Here, Henry Wadsworth, project engineer at Plextek, charts the rise of new energy harvesting technologies which are helping to power the growing Internet of Things.

To read the full article click here.