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 » Plextek

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

Being Your User

Nicholas Hill - Chief Executive Officer

By: Nicholas Hill
Chief Executive Officer

19th December 2018

Home » Plextek

One of the important steps in the Design Council’s recommendations for good design is called “Being Your Users” and is a “Method to put yourself into the position of your user.” Its purpose is “building an understanding of and empathy with the users of your product …” Approaching product design from this perspective is critical to ensuring that the features incorporated are actually beneficial to the user – as opposed to features that are of benefit to the manufacturer, for example, or “because we can” features that have no obvious benefit at all.

It’s clear that domestic appliances are becoming more sophisticated, a trend which is facilitated by the availability of low-cost sensors and processing power. This has some clear benefits, such as the availability of more energy- or water-efficient wash cycles for example. And if designers stay focused on providing something of value to the end user this is a trend to be welcomed.

In practice, I see examples of what looks rather like engineers wondering what else they can do with all this additional sensor data, rather than being driven by user need. One example is the growing size of the error codes table in the back of most appliance manuals. These may occasionally add value, but for the most part, I see them as reasons why the product you paid good money for is refusing to do the job it is supposed to.

Here’s an example: the “smart” washing machine that I own doesn’t like low water pressure. It has a number of error codes associated with this. What does it do if the mains pressure drops temporarily – e.g. if simultaneously a toilet is flushed and the kitchen tap is running? It stops dead, displays the error code and refuses to do anything else until you power off the machine at the wall socket, forcing you to start the wash cycle again from scratch. This gets even more annoying if you’d set the timer and come back to a half-washed load. In the days before “smart” appliances, a temporary pressure drop would have either simply caused the water to fill more slowly, or else the machine would pause until pressure returned.

In what way does this behaviour benefit the user? Clearly, it doesn’t, and a few moments thought from a design team that was focussed on user needs, “being your user”, would have resulted in a different requirement specification being handed to the engineering team. It’s a good example of what happens when you start implementing a solution without properly considering the problem you are trying to solve.

My “intelligent” dishwasher has a different but equally maddening feature: it doesn’t like soft water. Its designers have clearly put water saving above all else, and the machine relies on either hard water or very dirty plates to counteract the natural foaming of the detergent tablets. With soft water, if you try washing lightly soiled dishes on a quick wash cycle (as you might expect appropriate), the machine is unable to rinse off the detergent. About 20 minutes into the cycle it skips to the end and gives up, leaving you with foamy, unrinsed plates.

I say unable, when the machine is actually unwilling, as all that is required is the application of sufficient water to rinse off the detergent – which is what I, as a user, then have to do manually. Who is working for whom here? Once again the user’s needs have not been at the top of the designer’s agenda when the requirement specification was passed to the engineering team. A truly smart device would finish the job properly, using as much water as was needed, and possibly suggest using less detergent next time.

Unless designers get a better grip, keeping the end user experience on the agenda, I fear examples of this type of machine behaviour will proliferate. We will see our devices, appliances and perhaps vehicles develop an increasingly long list of reasons why they can’t (won’t) perform the function you bought them for – because they’re having a bad hair day today, which becomes your problem to solve.

All to a refrain of “I’m sorry Dave, I’m afraid I can’t do that.”

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One of the important steps in the Design Council’s recommendations for good design is called “Being Your Users” and is a “Method to put yourself into the position of your user.” Its purpose is “building an understanding of and empathy with the users of your product …” Approaching product design from this perspective is critical to ensuring that the features incorporated are actually beneficial to the user – as opposed to features that are of benefit to the manufacturer, for example, or “because we can” features that have no obvious benefit at all.

It’s clear that domestic appliances are becoming more sophisticated, a trend which is facilitated by the availability of low-cost sensors and processing power. This has some clear benefits, such as the availability of more energy- or water-efficient wash cycles for example. And if designers stay focused on providing something of value to the end user this is a trend to be welcomed.

In practice, I see examples of what looks rather like engineers wondering what else they can do with all this additional sensor data, rather than being driven by user need. One example is the growing size of the error codes table in the back of most appliance manuals. These may occasionally add value, but for the most part, I see them as reasons why the product you paid good money for is refusing to do the job it is supposed to.

Here’s an example: the “smart” washing machine that I own doesn’t like low water pressure. It has a number of error codes associated with this. What does it do if the mains pressure drops temporarily – e.g. if simultaneously a toilet is flushed and the kitchen tap is running? It stops dead, displays the error code and refuses to do anything else until you power off the machine at the wall socket, forcing you to start the wash cycle again from scratch. This gets even more annoying if you’d set the timer and come back to a half-washed load. In the days before “smart” appliances, a temporary pressure drop would have either simply caused the water to fill more slowly, or else the machine would pause until pressure returned.

In what way does this behaviour benefit the user? Clearly, it doesn’t, and a few moments thought from a design team that was focussed on user needs, “being your user”, would have resulted in a different requirement specification being handed to the engineering team. It’s a good example of what happens when you start implementing a solution without properly considering the problem you are trying to solve.

My “intelligent” dishwasher has a different but equally maddening feature: it doesn’t like soft water. Its designers have clearly put water saving above all else, and the machine relies on either hard water or very dirty plates to counteract the natural foaming of the detergent tablets. With soft water, if you try washing lightly soiled dishes on a quick wash cycle (as you might expect appropriate), the machine is unable to rinse off the detergent. About 20 minutes into the cycle it skips to the end and gives up, leaving you with foamy, unrinsed plates.

I say unable, when the machine is actually unwilling, as all that is required is the application of sufficient water to rinse off the detergent – which is what I, as a user, then have to do manually. Who is working for whom here? Once again the user’s needs have not been at the top of the designer’s agenda when the requirement specification was passed to the engineering team. A truly smart device would finish the job properly, using as much water as was needed, and possibly suggest using less detergent next time.

Unless designers get a better grip, keeping the end user experience on the agenda, I fear examples of this type of machine behaviour will proliferate. We will see our devices, appliances and perhaps vehicles develop an increasingly long list of reasons why they can’t (won’t) perform the function you bought them for – because they’re having a bad hair day today, which becomes your problem to solve.

All to a refrain of “I’m sorry Dave, I’m afraid I can’t do that.”

Save

Save

Save

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Further Reading

Technology Specialists for Safe Cities

Plextek features as a “Company Focus” in Counter Terror Business magazine to discuss how cutting-edge technology is being applied to create safer cities.

We showcase solutions that are currently tackling the biggest security and public safety challenges in transport, government and critical national infrastructure.

To read the full article please click here.

For more information, contact Nick Koiza, Head of Security Business, via nicholas.koiza@plextek.com

Plextek and Wave Tech Partner to Revolutionise Airport Runway Safety

Nick Koiza, Head of Security Business features in ‘Counter Terror Business’ magazine this week. He discusses Plextek’s recent collaboration with RF signal technology company, Wave Tech on a foreign object debris detection radar that has the potential to save lives.

To read the full article on page 10 please click here.

For more information, contact Nick via nicholas.koiza@plextek.com

Cambridge, UK – 18th October 2018 – This week Plextek showcased their mm-Wave Radar on the Government of Dubai stand at GITEX 2018.

The other technology firms that were invited to join the stand were Esharah Etisalat Security Solutions, Airbus and Nokia.

Our Project Engineer Edson DaSilva showed how this technology can be applied for detection of a range of objects, for example:

– people

– vehicles

– UAVs

– even objects as small as a nut and bolt.

Threats such as Foreign Object Debris (FOD) on runways can pose a serious risk to passenger safety meaning this technology is key consideration for organisations.

Edson DaSilva, Project Engineer said:

“Our mm-wave solutions operate in covert frequency bands making them extremely difficult to intercept and have been deployed for diverse security applications, for example, drone detection, sense and avoid, perimeter security, protection of critical national infrastructure, border control and airport protection, and also prevention of contraband drop off at prisons.”

Nick Koiza, Head of the Security Business at Plextek was delighted to have had the opportunity to support the Government of Dubai:

this technology demonstrates our low size, weight and power mm-wave solutions, an area where customers from across the globe have benefited from reliable detection of objects of varying size and speed, including fast moving, small aerial targets.”

To find out more about how our radar technology capabilities could fulfil your security requirements, contact a member of our Secure Technologies team: security@plextek.com

Notes to editors

Based near Cambridge, UK, Plextek designs new products, systems, and services for its clients in a diverse range of industries including defence & security, medical & healthcare, and wireless communications.

Central to its culture is the company’s ability to innovate, taking an idea from concept to market. For more than 25 years the team of consultants, engineers and project managers has turned our clients’ business opportunities into commercial success, designing, manufacturing and supplying leading-edge products. Supported by our network of suppliers, commercial partners and research organisations, Plextek is the trusted partner of choice for more than 300 commercial clients, government agencies, and ambitious start-up companies.

For images, information or interview requests, please contact: Adam Roberts via email: press@plextek.com or call: 01799 533200