As an ex-military man, DARPA’s Dr David Honey is well suited to the job of developing technology that refines communications across the war zone. Jon Excell reports.

The US administration’s chaotic and thus far disastrous struggle to restore peace to Iraq, coupled with the demands of its nebulous ‘war against terror’, has placed its military forces in unfamiliar territory.

In an effort to address this and to stimulate the development of technology better suited to the current strategic environment DARPA, the US military’s R&D agency, recently merged its two big ideas factories — the Advanced Technology Office (ATO) and Special Projects Office (SPO) — to form a Strategic Technology Office (STO).

At the new department’s helm is former B52 pilot Dr David Honey.

Since leaving the US Air Force Honey, who holds a PhD in solid state science, has risen through DARPA’s ranks, working first as a programme manager, then as a deputy office director in the Microsystems technology office, before arriving at his previous post as director of the ATO.

While many aspects of Honey’s role are similar to his duties at ATO, the big difference is the wider remit of the new office. ‘The focus of what we do, developing technologies that have a theatre-wide impact and involve multiple services, is different from what we focused on before,’ he told TheEngineer.

The office has a number of so-called ‘thrust areas’, which span fields such as space technology, maritime operations and chemical/biological issues. But according to Honey, the most significant and promising of these areas is the office’s activity in network centric warfare: the use of high-speed communications networks to connect weapons, sensors and command and control centres.

He explained that the challenge of establishing effective communications networks for the military is somewhat harsher than the challenge of providing civilians with mobile phone access.

‘Because they carry cell phones and Blackberrys around, a lot of people think that they’re mobile. What they don’t realise is they are tied to cell towers. Move outside that cell tower range and you’re going to have a problem.’

Honey added that while it is sometimes possible to make use of off-the-shelf commercial equipment, a highly mobile force cannot afford to be restricted by this cell-tower- dependent environment.

‘When you move into the mobile environment, the laws of physics dictate that there is only so much RF spectrum available and then the laws of the various countries limit that spectrum availability in an even more restrictive sense.’

One project designed to provide networking capabilities in the face of these restrictions is the optical and RF combined link experiment (ORCLE). Here, engineers are developing high-bandwidth communication technology that can be used between moving platforms. This hybrid technology combines laser and radio frequency communications into a single system and can automatically switch between the two transmission modes based on the type of message sent and on atmospheric conditions.

It is effectively a military version of free space optics — a commercially available technology that uses light propagating in free space to transmit data between two points. But while free space optics is limited to use between buildings, Honey said ORCLE will enable high-bandwidth communication between moving aircraft and moving ground vehicles or aircraft and ships.

‘We’re developing laser terminals unlike anything you would see in the commercial world,’ he claimed. He explained that the terminals can reach across, independent of the user, establish the point-to-point links and stitch themselves together to build a true network.

‘They can monitor the health of that network and, if necessary, switch over high-priority traffic to a co-located RF channel. If there are any degradations in the optical network it will sense them itself and, hands off to the user, switch that traffic over.’

He said the systems, which work by line of sight, could ultimately have a range of more than 100km (62 miles) if platforms are placed at the right altitude. Initially Honey expects each laser channel to run at 2Gb/s but once the system has been demonstrated he believes it will be scaleable to much higher data rates.

Over the last year DARPA has completed an extensive series of ground experiments where it simulated aircraft links between static points. In about 12 month’s time it will attempt the world’s first airborne demonstration of this kind of system.

Honey said after that the technology should be in use on the battlefield within the next couple of years.

Another promising communications breakthrough is the work being carried out on multiple input/multiple output (MIMO) radio technology which, said Honey, could offer a solution to the problem of Multipath.

This phenomenon, familiar to many mobile phone or radio users, occurs when a signal from a transmitter is reflected and refracted by objects between the transmitter and receiver. The signal is broken up and scattered and multiple signals end up arriving at different times — causing the signal to randomly strengthen or drop out.

Using MIMO, multiple antennas on the transmitter and receiver can be used to pick out the strongest signal at any given moment. As with free space optics, MIMO technology has been demonstrated in the commercial world but Honey’s team is now attempting to modify the technology for the mobile military user.

‘There are many challenges in figuring out how long those channels exist. In a static environment they can exist for a long time. We had to work through the details of how you build the hardware, how you build it in an affordable fashion and demonstrate that you can do MIMO on the move in an urban environment.’

Honey added that his group recently demonstrated this is possible during tests in New Jersey.

While both ORCLE and the MIMO project are relatively mature and began before the STO was formed, the office recently published a list of possible new thrust areas that Honey hopes to develop projects for soon. Among the areas outlined in this document are extremely large space apertures and structures, including structures that have very small payload volumes, such as rigid inflatables.

The document shows the office is interested in developing a range of technologies for detecting and monitoring underground facilities, systems for non-acoustic bullet detection and for detecting indirectly fired mortars as well as underwater vision devices for military divers operating in a high-salt environment.

It is a varied pallet of aims and it only works, according to Honey, because of DARPA’s traditional bottom-up approach, where the ideas come from the technologists and the programme managers rather than from top-down directives.

With so many ideas coming from below there is, said Honey, ‘a fairly substantial early mortality of ideas.’ ‘But,’ he added, ‘the interesting thing about DARPA is that failure is accepted as part of the overhead and part of the cost of doing business.

‘The first question I ask programme managers when they tell me “it failed, it didn’t work” is “should we give you more money or more time?”

‘In almost every case the answer is no, because they’ve done the appropriate post mortem and figured out what it is that we didn’t know that prevents us from getting there — and we move right on to the next project.’