A true game-changer? (Aveillant)
A UK company has made what has been described as the biggest advance in radar technology for 50 years. TIM ROBINSON investigates ‘Holographic Radar’.
Radar technology has come a long way since the days of Watson-Watt and the first tests using BBC transmissions that revealed aircraft reflected radio waves. Since that first key discovery, radar has massively increased in capability.
Yet, in a lecture at the RAeS HQ on 26 March, a small UK company from Cambridge contended that, despite the sophistication of the latest primary survelliance radars — their development had arguably led down a limited path.
Giving the lecture was Dr Gordon Oswald, Chief Technology Officer, Aveillant — a radar scientist who had previously pioneered ‘though ice’ radar to map the Antarctic. At Aveillant, he has been behind turning an ‘ultimate radar' — one that stares, rather than scans, into reality. This breakthrough is now possible, thanks to advances in parallel computing — but overturns nearly half a century of thinking about radar.
The limitations of sequential scan
Dr Gordon Oswald, Aveillant Chief Technology Officer explains the technology at RAeS HQ.
Dr Oswald explained that today's radars face new challenges — such as the intensification of air traffic, the introduction of wind farms, the growth of drones and the increased pressure of resource of the electromagnetic spectrum by competing demands. However, he argued that the way in which radar had developed over the past 80 years had led to a situation where the technological focus was on the waveform, antenna and agility — rather than the target itself. The ‘sequential scan’ he noted of traditional radars (even electronically-steered AESA beams) meant that a radar only ever ‘glances’ at a target — spending less than 1% of ‘dwell’ time on a particular contact. He noted that, since ‘sequential scan’ became the norm, the majority of technological effort has been expended on getting more out of this 1% glance or by agility, moving between different targets faster. Says Oswald: “The industry has spent billions to get more out of that 1%”. Aveillant's 3D holographic radar, he explains, turns this on its head — making surveillance ‘target-centric’.
3D Holographic radar
The Theia 384 gives 360deg coverage up o 40nm (Aveillant)
Building on theories of an ‘ultimate radar’, Aveillant's 3D Holographic Radar dwells continuously on every target at once, to occupy a volume of space up to 40nm. This gives a rich Doppler resolution of targets with a 1/2-second update rate allowing detailed information on the target to be extracted, processed and then classified. The longer the target is visible, the more information can be extracted. Oswald has calculated that a 3D Holographic Radar gives better information than traditional radars by a ‘factor of 100’.
An analogy, he says, is “Compared to traditional radar, instead of using a flashlight to keep track of a £100 note in dark room with fans and full of £5 notes — it’s like switching on the room light.”
A key to the performance of the radar is a simple signal, that allows maximum information to be derived from the return. “We believe the interrogation signal should be as simple as possible,” explains Oswald. Fast computers then do the hard work of crunching the raw data. Thanks to today's cheap graphics card parallel processing power, Oswald says: “This wouldn't have been affordable even ten years ago.”
There are other advantages. The static modular solid-state array is made up of small modular 'tiles' (the world's first ‘flat-pack’ radar) and can be mounted anywhere — such as the side of existing buildings and arrays networked together. With no rotating dish or mechanical components, there are also no moving parts — increasing reliability in the field.
Identification and survelliance
The results of this ‘staring’ radar is that a Holographic Radar can perform both survelliance and identification roles — thanks to the immense amount of information it collects. Some comparison is that every second a traditional radar will collect 100,000 ‘resolution elements’. For Aveillant's 3D Holographic Radar this jumps to 2·4billion — providing a vastly improved and enhanced level of information. In tests it can even tell the diameter of the propellers on a small GA aircraft.
Clutter is removed in windfarms using the radar. (Aveillant)
The capacity of this ‘staring array’ 3D radar which generates volumes of data on targets means that it is particularly well suited for wind farm mitigation measures. While other radars attempt to ‘solve’ the issue of wind farm clutter by making the blind spots or blanking areas smaller, Aveillant's approach means there are no blind spots. The wind turbine is tracked, classified and then removed — it is just another target to the radar.
Amazingly, in comparative field trials in the US (which saw Aveillant pitted against several large established radar companies), its 3D holographic radar actually performed better in the middle of a wind farm — than the baseline. Says Oswald: “Clutter to us is just a target you haven't got enough information on yet.”
The radar can also track small UAVs.
Another benefit with this persistent surveillance of airspace is the ability to track very small targets — including UAVs or drones. In a field trial, Aveillant's radar was able to track a small (35cm) 1·2kg DJI Phantom quadcopter succesfully. For airports (or other critical infrastructure operators, such as nuclear power plants) concerned about the proliferation of small UAVs, holographic radar may be a useful solution.
Low spectrum footprint
Spectrum efficiency is another advantage. Unlike current PSR (primary surveillance radar) with their own individual frequencies, holographic radar operates on a single common 2Mhz L-band frequency. It also needs less ‘spare’ bandwidth kept clear on either side of its frequency, unlike legacy radars. This low footprint will become more important to airport operators, as the UK seeks to exploit the electromagnetic spectrum for commercial telecomms which means that there may be narrower slots available for radars in the future. With the UK Government set to release some 500MHz of the public services spectrum below 5Ghz to commercial bidders, spectrum efficiency, predicts Aveillant, will become more and more vital.
At the moment Aveillant is focused on the airport PSR market. However, as the technology matures there could well be additional appilications. However, Aveillant is cautious in speculating too much about what 3D holographic radar can do. “It's primarily about surveillance, not about putting missiles on targets”, says Oswald. For example, the maximum range is 40nm. Its maximum range can be extended out further but a better solution is to network more tranceivers/receivers to cover a given volume (unlike traditional radar, the two need not be co-located). Aveillant explains that the radar is at its best when surveilling a defined space or volume. Military applications, though possible, will also need the computer algorithims to be tweaked to cope with more dynamic, fast-moving targets — and resistance to electronic warfare will also be another factor.
At the RAeS lecture, the company refused to be drawn into how capable 3D holographic radar might be against low observable or stealth aircraft — but it is clear that the amount of information it can extract from normal targets is extremely impressive. There may be a latent anti-stealth capability waiting to be exploited in the future.
The first Theia16 holographic radar will enter service this summer. (Aveillant)
Perhaps most impressive of all is that this revolution in radar technology has already made the leap from R&D field trials at Prestwick Airport to operational use. Currently, Aveillant has three products on offer, the Theia 16A (with a range of 5nm), the Theia 64A (range 20nm) and the Theia 384A (360deg coverage out to 40nm). This summer will see a Theia16A become operational at East Midlands Airport in the UK, where it will be used for wind farm mitigation.
Avelliant hopes to follow this up in the UK with perhaps a ‘cluster’ of one or two airports as early adopters of 3D Holographic Radar, with the intention of growing it out gradually. To cover the entire UK, Aveillant calculates it would need some 40+ sites.
It is rare in a mature industry such as aerospace to discover a product that throws out of the window much of the technological approach of the past 80 years. However, Aveillant appears to have developed a serious competition for legacy radars — and the future potential seems extremely exciting. Most ironically for aviation historians perhaps, Oswald notes that this combination of simple waveforms and high-speed computers harks back to the very beginning of radar: “We are just putting computers into Chain Home.”