There aren't many of us who like to be early adopters of any new technology, particularly if it's expensive and you have to pay to get your hands on it — who wants to be an 'unpaid beta-tester', after all? Perhaps this explains the relatively slow takeup of HD technology amongst broadcasters across the globe. Many would rather wait until a few years of inevitable debugging and design tweaks have passed before committing themselves to costly high-definition refits.

But if your role is to build studios and broadcast systems, and a valued client demands a fully HD-compliant system, you can't prevaricate, unless you want the contract to go to a competitor. Such was the situation when OB services supplier Arena TV asked the systems integration arm of audio facilities company Total Audio Solutions (TAS) to help them build an HD outside broadcast vehicle. This wasn't any old OB van: it was to be a flagship truck, the largest HD-capable mobile unit in Europe, built to the largest size legally permissible on European roads (17.5 metres) and with a completely HD-compliant signal path throughout. What's more, the vehicle in question, Arena Unit 7, was commissioned in 2005, when there was considerable uncertainty about exactly what form HD transmissions would take, particularly on the audio side.

It was a tough contract, but as Total Audio's Managing Director Peter Knowles acknowledges, his company has something of a reputation for trying out new equipment and adopting new standards early, which is partly why Arena came to them in the first place. The company have been building OB vehicles since their first year of business, 1996, when they put together the first of their well-known TArdiS audio mobiles for their own use. However, they only took the leap into large-scale systems integration work in 2005, when Peter made former freelance systems engineer and operational sound supervisor Andy Unsworth a full-time employee.

Originally a Systems engineer at AMEK, Andy also spent many years at Grenada as a Sound Supervisor, which gave him the mix of operational and systems engineering experience that Peter Knowles believes lies at the heart of Total Audio's success. "When we design systems, we're looking at the project both from the engineering perspective and also from the standpoint of how easy this thing will be to use, because we're users ourselves," he explains. "Andy fit right into that, and bringing him in was a catalyst for the Systems side of Total Audio. He's got an excellent reputation within the industry, and his feet haven't touched the ground since he started here. It was partly on the strength of his reputation that we got the job of building Unit 7 for Arena — he worked as Head of Sound there for a couple of years."

TAS like to approach truck-building projects in three parts: the vehicle, the system, and the equipment that makes up the system, which itself is sub-divided into audio, video and the 'glue' that connects everything together, such as cabling, interfaces, converters and so on. As far as Total were concerned, the first part of the Arena Unit 7 project was relatively simple; the sheer scale of the truck meant that it could only be built in the United States. Andy Unsworth: "When you get into expander trucks — Unit 7 has an expander section on either side running the full length of the unit — that's seriously specialist vehicle stuff. To make a chassis like that here in the UK would cost three times more than it does to have it built in the States, even allowing for the shipping costs and the fact that some of the parts have to cross the Atlantic twice, like the air-conditioning system, which is British, and the axles, which were built in Wales." The chassis was therefore constructed by Gerling Associates in Ohio.

When it came to the rest of the truck, however, both Arena and Total Audio were aware that they were taking something of a leap into the unknown. "One of the original briefs was that the truck had to have an HD architecture throughout, and be a complete multi-role vehicle, capable of handling any OB job, from a Sky Premiership match to a BBC Light Entertainment job," says Andy. "That meant that we had to put a lot of kit in there, because the truck had to be able to cope with any scenario. And at the start, we didn't really know what those scenarios were going to be, because very few people had really done any live HD transmissions on that scale! When we started talking about the design, they weren't even sure whether we should provide 5.1 audio facilities, although pretty quickly, both Sky and the BBC settled on Dolby E-encoded 5.1 audio as their preferred transmission standard for HD Surround, so Arena decided that Unit 7 needed to be able to deal with that too."

Fortunately, Arena were aware that this truck was breaking new ground, and that it would be expensive. "They didn't put any kind of budget on it," says Andy, "perhaps partly because no-one really knew exactly what something like this would cost. I spent a lot of time with Pete Love, Arena's senior vision engineer, thrashing out the spec — there was a lot of overlap between the audio and the video side, and we shared a lot of concerns, like the fact that we didn't have much rack space. So much on the vision side hadn't been tried before. The HD video routers were enormous, 240 x 360 Pro-Bel Sirius units, with built-in upconverters and downconverters, and Arena also decided that they were going to put a completely flat production stack of LCD displays in, which was a bold move. That saved a lot of space, and allowed us to have a much larger area devoted to Sound than is usual in an OB truck that size." For the full Unit 7 plan and spec, see www.arena-tv.com/pdf/u7.pdf.

"The other way we saved space was by using Axon's modular converters and encoders — their Synergy system," continues Andy. "I was talking to a lot of colleagues and manufacturers in the industry, seeing what people thought about how to go about building systems like these, and it turned out that Sky were already using some Axon kit. We decided that they could supply us with all the 'glue' for the truck: all the video ADs and DAs and audio converters. But then it turned out that they were working on Dolby E 5.1 encoders and decoders and embedders and de-embedders as well. They come on cards as part of the Synergy modular system, and you put the cards into these 16-slot, 4U boxes. We had planned to use dedicated Dolby kit for all the Dolby E encoding, but this meant we didn't need to put in separate boxes for all of those jobs, so we had more space, more flexibility, and a lot less cabling. In turn, this reduced the power and weight across the whole design. The only problem was that a lot of the Axon options weren't available when we were ordering the gear; it was all in prototype form. They were saying 'yeah, we're working on that, and by the time your truck's nearly ready, we should have it done'! It was a bit of a risk from Arena's point of view, but it did pay off...

"Another reason for going the Axon route was that they have delay compensation built into their cards. One of the problems with Dolby E encoding is that it causes a delay in the audio path of about two to three frames with respect to the video. Again, if we'd gone the Dolby route, we would have had to put in separate delays. We could have done that, but I really wanted this truck to be as simple as possible, so that if you were doing a 5.1 mix, the audio would appear at the tailboard already timed in with the video. I didn't want the video guys to have to worry about patching in separate delays of their own to make it all work.

"Apart from that, the setup was pretty conventional apart from the Calrec desk. But even there, by the time Calrec came to do the desk for Unit 7, they'd already done one or two 5.1-capable Alphas for Sky and a couple of others, so they knew what they were doing. Fundamentally, there are four main 5.1 output buses on the Calrec, which are Dolby E-encoded by the Axon cards. The four outputs are then made available on the router, after which they can be embedded and sent to the tailboard."

Unit 7 was delivered to Arena on time in early Summer 2006. By that time, Arena had decided that they wanted Total Audio to work on a second truck to the same HD specification, which became Unit 8. But this time, Peter Knowles decided they'd do things differently. "Unit 7 was built at Arena's hangar in London, and when Unit 8 came up, I didn't want Andy to have to spend five months away from home again. Also, I thought that as that side of the business was growing, we really ought to have our own facility. So we bought a patch of land on the same industrial estate as our offices, and built our own 8000-square-foot Systems Unit on it, specifically designed for building trucks. It's got all the right power supplies, wire-stripping equipment, welding and cutting gear, and a fully equipped spray shop. Everything in there was built with Unit 8 in mind, from the building's layout to the power supplies, working on the assumption that you can never have a bigger truck-build job than that. All of the systems work we do now is built in there." "We can build anything up to a non-expanding artic in house now," adds Andy.

With most of the difficult preparation done in the design of Unit 7, work on Unit 8 was comparatively simple, as the required spec was almost exactly the same, although Arena did choose to make the Production area slightly larger and reduce the Engineering and VTR areas correspondingly. The latter two areas were also swapped from left to right, which caused a few headaches with cable runs. Nevertheless, Unit 8 was also delivered to Arena on time in December 2006.
 
Looking back, Arena took a gamble by paying a lot of money to build trucks to HD specifications that might have been unnecessarily advanced. Does Andy think it was worthwhile? "Arena made some very brave, forward-thinking moves — and on two trucks, too! Mind you, it was incredibly costly, particularly the audio side. Putting Dolby E on those trucks must have added 130 to 140 thousand pounds to the build cost of each one, or possibly even more than that. Nobody will care if it's paid for itself in a few years because 5.1 becomes the standard. But from what I understand, they haven't done much 5.1 with either truck yet, although I know they did the Queen's birthday party for the BBC with Unit 7 in 5.1, and that worked really well. It's still too early to tell, really — some of the large broadcasters I'm dealing with haven't officially worked out a transmission format for HD video yet, let alone 5.1 audio, although they're all having to have HD-compatible equipment installed when they do refits."