live with latencies in the 50 to 60ms range, and this is something we can achieve using Gigabit Ethernet and GigE Vision today.’ Fifty to 60ms, he says, is around the optimum latency, as it leads to an unobtrusive disparity between somebody’s action – i.e. turning the steering wheel – and an observable reaction – i.e. the vehicle’s viewpoint turns. ‘If there’s too much disconnection between turning the wheel and the visual representation, then the human brain has a hard time coping, and the vehicle becomes very difficult to drive. Even driving in our daily lives it would be very difficult to cope with, but when translated into the deserts of Iraq or Afghanistan, where people’s lives are on the line, it becomes something else entirely,’ he says.


‘We don’t go bolting these cameras on willy-nilly; they have to be integrated carefully’


In order to ensure that the cameras and the


networks by which they’re connected perform to the required specifications, Pleora’s development kit contains drivers that optimise the Gigabit Ethernet cards so as to minimise both the latency and the jitter of the video. Rigorous testing is also important: ‘Our military contractors will do what they call photon-to-photon testing, taking a measurement of when the photon of light goes into the camera, passes through the system, and comes out at the monitor… and if that is within an acceptable range, then they certify the product,’ says Chamberlain.


Working with military customers The military can be a difficult market to navigate, with various tiers of bureaucracy between the high-level body commissioning a new tank, aircraft, or capital ship and the various developers of the imaging equipment, which finally makes its way into the final piece of material. For the UK’s MoD, for example, defence procurement is largely handled by the Defence Equipment and Support organisation based at Abbey Wood, near Bristol. Ian Palmer, a project manager at UK- based night vision specialist e2v, has worked with the specification writers based at Abbey Wood, and he has found that the first step is ensuring that the customer has a sufficient understanding of the capabilities of cutting- edge technology. ‘When it came to some of


our customers’ low light requirements, we had to do some significant work with members of the contracting project teams in order to make sure they had an understanding of reality – that their specifications were realistic,’ he recounts. Palmer gives the example of a specification


for imaging equipment for a certain military vehicle, which was initially supposed to be able to allow the users to see a person in a ‘threatening posture’ at 600m in low light conditions. In this case, Palmer says, convincing the customer of the impracticality of their expectations was made easy by the use of e2v’s dark tunnel facility. ‘We brought the project team down to our facility, and made targets that corresponded to what the cameras can see at 600m, and then we ask if they can see it… and of course they can’t. It’s a bit of a challenge to bring them back to the reality of what is practically possible. We still fit into the category of having the most sensitive cameras in the world, and so we can say “that’s as good as you’re going to get.” Everybody’s always pushing the boundaries,’ says Palmer, ‘but there are fundamental limits of noise and frame rate that come together to say “if you want to run at this speed, under these lighting conditions, with the inherent noise of the system, then that’s the contrast and target recognition that you’ll be able to achieve.”’ In other low-light applications, he adds, a slowed frame rate could be used to integrate-up image data so as to achieve better contrast, but driving or spotting a moving target requires a certain frame rate.


Is mil-spec really so special? Imaging performance aside, military applications have traditionally meant harsh working conditions, and so the systems will often be specified with highly specialised mechanical or environmental tolerances, including temperature, shock and vibration, and electromagnetic interference. According to Chamberlain, Pleora meets these requirements through thoughtful design, rather than through use of certified military specification (mil-spec) components. ‘The way our military contractors will typically engage with us is to use our off-the-shelf products for initial tests, prototyping, and proof of concept, and then they will use our hardware as a reference in order to ruggedize that design. ‘They will take our proven hardware design, lay it out in the form factor they want, and then they’ll change-out certain components for mil-spec components,’ he says. The company ensures throughout the design process that it uses components that have a mil-spec equivalent. ‘It costs some effort on our part, and it doesn’t


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