“One New Year’s Eve the incoming power source lost the neutral and sent 400 volts through the truck,” Dovale recalled of a long-ago show.“Everything not connected to the UPS blew to pieces.”
Designing and building an outside broadcast vehicle is mostly science but also an element of art. Balancing features along with flexibility while still needing to stay under critical weight and power loads is a tricky business. Designing a truck for Astro in Malaysia proved to have its own challenges as Steve Burgess, technical director for Megahertz/KIT digital Broadcast Systems Integration explains.
“Broadcast equipment has certainly become smaller over recent years, and this allows more firepower to be accommodated in fewer rack cabinets. The downside of this, though, is that the higher packing density means that air flows and cooling need to be carefully planned.”
Some outside broadcast operators are lucky enough to win long-term contracts for specific events – usually sports – and can build trucks which are designed around a precise set of requirements. Apart from the commercial benefits of an extended contract, this makes the truck incredibly productive because it can turn up to any site ready to go, as each job is more or less the same.
That is a luxury not open to most businesses, who have to work across multiple events and therefore with multiple requirements. So there is a fundamental imperative, when designing a truck, to build in flexibility. The unit will be most useful, and capable of earning maximum revenue, if it can easily tackle a broad range of jobs without spending too much time back at base being reconfigured.
Flexibility in equipment is the most obvious factor, and this is widely recognised. Operators will load the number of camera channels they need for a job. Often customers will specify a standard number of cameras for a truck build, knowing that when bigger jobs come along they will be able to rent in more chains as required.
The same applies to production servers. Some jobs require virtually every camera to be iso recorded, with a number of super slo-mos, and the ability to replay any at a moment’s notice; others will have much simpler replay requirements. It makes sense to load only the number of EVS channels you need.
You might offer flexibility on other equipment, like graphics and editing. Editing is a simple one to support: put a Mac in the technical area and let the operator choose to run Premiere, Media Composer or Final Cut Pro. For graphics, though, you might need to swap units in and out to suit those who prefer – or who have templates in – Pixel Power, Vizrt or Inscriber, for example. That means designing the rack layout to make it easy to remove one box and replace it with another.
For those jobs where equipment is not needed, like extra EVS controllers or graphics keyboards, put blank panels in the desk rather than leaving holes. It creates more working space which will make everyone feel more comfortable. For graphics and edit desks, simply attach the keyboard to a panel which can be flipped over when it is not required.
Operating flexible equipment means that the core infrastructure has to be designed for ease of reconfiguration. The ability to store and recall router configurations speeds this set up.
Putting everything into one router helps; On recent projects we have used the Madi protocol to carry large numbers of audio channels over a single “video” cable, which means it can go through the same router as everything else without investing in a top-end, multi-format router.
We are probably not yet at a stage where fibre within the racks is practical: fibre ports are not yet offered on every device. The balance between the reduced weight of fibre cabling and the additional weight of optical to electrical converters should be considered, though.
Weight is always an issue, most obviously to stay within the legal road limits and the capacity of the vehicle, but also because every unnecessary kilogram-kilometre has to be paid for in fuel and environmental impact. For this reason, fibre camera connectivity is becoming more attractive than triax, although there remain a large number of sports venues where the triax is already permanently installed so pulling in fibre would be a waste of rigging time.
You may have noticed I skipped over one of the very first design decisions: the size of the vehicle. While huge, multiple-expansion articulated trailers often grab the headlines, they are not the only option, and flexibility means choosing the right body.
Over the last year or so we at Megahertz/KIT digital have built two new outside broadcast units for Astro in Malaysia, as part of their migration to HD. The first was a 13.5 metre expanding trailer, but OB2 is a fixed three-axle Volvo truck with a single expanding side.
Dennis Dovale, head of operations at Astro, explained: “In Malaysia we are restricted by the road size and we are restricted by the venues so this is the perfect truck for us. OB1 [the trailer] we built because we needed it for big sporting events, but if we build more we will be looking at the OB2 style of vehicle.”
Dennis made the key point that the vehicle has to be able to get to the venue and park conveniently when it arrives. So something that is not going to cause problems on narrow roads is a good plan. The smaller footprint also helps when the unit has to work in city centres.
Clever design can mean a smaller vehicle can achieve almost the same production capabilities as the largest trailer: while our OB1 for Astro is nominally a 20 camera unit, OB2 is designed for 16 cameras as standard. It supports the replay, audio, graphics and editing functionality that practical productions demand.
Broadcast equipment has certainly become smaller over recent years, and this allows more firepower to be accommodated in fewer rack cabinets. The downside of this, though, is that the higher packing density means that air flows and cooling need to be carefully planned.
Environmental conditioning obviously needs to be matched to the application. For a truck designed for northern climes, likely to see service on ski racing, the heat pump function offered as standard by some air-conditioning manufacturers is unlikely to be sufficient. Consideration needs to be given to a hot water-based radiator system along with electrically-heated floor mats in order to keep the operators comfortable.
The Astro units, on the other hand, are designed for the steamy jungles of Malaysia, so we had to find a way of fitting in a huge amount of air conditioning. Trying to pack 30kW worth of cooling into the vehicle was a challenge, while ensuring that it ran silently in operational areas.
With that amount of energy needed just for the environmental systems it is a good thing that broadcast hardware is getting more efficient. But, as with rack space, the temptation is to take the modern compact, low-power units and just have more of them, increasing the production capabilities and flexibility of the truck.
On location, the integrity of the power can be a problem. A large uninterruptible power supply adds weight and takes space, but it can be invaluable. “One New Year’s Eve the incoming power source lost the neutral and sent 400 volts through the truck,” Dovale recalled of a long-ago show.“Everything not connected to the UPS blew to pieces.”
That is why Astro specified UPS installations in their new trucks capable of sustaining the whole truck for 10 minutes or so. That’s enough to switch from a ground source to a generator without any disruption whatsoever to the production, even live on air. “
We have found in the last couple of years that if we put a big UPS in the truck it does not cost that much money,” emphasised Dovale. If it saves one production it will more than pay for itself.
So, while the core equipment for an outside broadcast unit – the cameras, switchers, servers and so on – are vital decisions. Equally important are the practical considerations on how you will use them. Before you sit down to design the truck, ask yourself where it is going to go, how you will power it and how you will keep the equipment and its operators comfortable when you get there?
Then consider how flexible you need it to be. If it is going to be covering a major sports event one day and an opera the next then you need to be able to reconfigure the equipment and how you use it, quickly and without the need for a team of engineers.
If you work with an experienced systems integrator then together you should be able to define a set of requirements to meet your needs. Then trust the design engineers to make this a reality, providing production flexibility and convenience within the confines of practical weight, space and power limitations.