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High-tech hide and seek

It's not difficult to imagine the pressure and fear felt by police and special security forces poised to enter a building that's thought to conceal dangerous and possibly armed fugitives or terrorists. So they, like me, will be interested to see how a through-wall radar-sensing device can help in these situations.

Launched in the U.K. by Cambridge Consultants, Prism 200 features a range of 20 metres and answers the crucial "is anyone behind the wall and what is their activity pattern" questions. Such is the difference between a successfully concluded siege situation or an operational disaster.

Okay, so prototypes of these systems have been around for a few years. However, this latest version really does offer some very smart help to security forces. Not only does it provide images of people in other rooms, but these images can be viewed in 3D and rotated. This arms security forces with various plan-of-action scenarios.

Basically, the system uses impulse radar much like that inherent in flying bats—it sends out a signal and then senses the echoes. The frequency rate is around 100 pulses/s and works on Ultra-Wideband at 2GHz. Thanks to the latter, the system can send a transmitted wavelength short enough to penetrate buildings with reinforced steel structures. Another advantage of Ultra-Wideband is that it offers the ability to make accurate distance judgements, which is critical in a siege situation.

DSP technology lies at the heart of the electronics analysis. This processing enables the identification of static and moving objects. During operation, icons are displayed underneath the radar screen. These give the operator a fast one-touch means of changing parameters, such as the type and angle of view or range factors.

A particularly clever piece of work by Cambridge Consultants concerns a layer of signal processing that enhances the contrast between real human subjects and secondary reflections returning via an indirect path. A software layer in the system can distinguish between a person or persons and a confusing mass of reflections. This is important when it comes to certain locations like offices. These are full of reflecting services that can clutter returned radar images that need to be clearly analysed.

And you don't need to be Sylvester Stallone to use the system. It all comes in a case about the size of a laptop bag and weighs a mere 5.4kg.

TAGS: Components
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