Top 10 OB challenges

    Key considerations to take into account when building an OB vehicle.
    SPECIAL REPORTS, Exhibitions coverage, Top 10


    With the upsurge in live HD production there are many key considerations to take into account when building an OB vehicle.
    Technical director of Megahertz Broadcast Systems, Steve Burgess, examines the key challenges that need to be overcome to ensure that the customer’s requirements, and integration needs, are being met when completing the build out of a fully functional, flexible and robust OB vehicle, whatever the size.

    The challenges presented by the design and build out of HD OB vehicles are many. 

    Chassis Choice

    One of the first and most important challenges facing the design team is the choice of base vehicle chassis. At one extreme, for large production vehicles a suitable trailer must be chosen. Care must be taken when selecting suspension, axles and brakes that are appropriate for the environment and terrain in which the vehicle is to be used. Some of the most visually impressive vehicles can be built on coach bodies. The use of such vehicles bring its own set of problems including, restricted payload and limited internal head height.

    Many medium-sized OB vehicles are still built on chassis-cab designs. These offer much more flexibility in terms of size and load carrying but also enable the potential of refitting the OB body to a replacement chassis should the latter deteriorate over time. However, as with all vehicles, it is critical to check at an early stage that the unit is type-approved for the country of destination.  Panel vans offer a low-cost solution to small/medium sized OB requirements.  For instance, the Mercedes Sprinter seems to have become the de-facto standard in some countries for the SNG (satellite news gathering) market. 

    Similarly, at the smallest end of the scale, we are seeing a number of conversions undertaken using the new breed of MPV’s for use as editing or SNG vehicles.

    Our own experience points to that fact that OB vehicles chassis come in all shapes and sizes — from an SNG Humvee recently completed for Telemedia in South Africa, to one of the most ergonomically designed, triple expandable OB production trailers built for SIS LIVE in the UK.

    Vehicle service and support

    Besides the issue of type-approval mentioned above, the selection of chassis must also take account of the vehicle support offered in the destination country. There is little use of fitting out a $1.6 million OB vehicle if it cannot be kept on the road because of the lack of engine spares or indeed engine servicing capabilities locally.  

    The weight loading of the vehicle is always critical and, although the overall weight of the finished vehicle may be within the manufacturer’s specifications, many of these are originally designed as delivery vehicles and as such may be expected to spend half of their time empty. Often, modifications are required to the chassis to ensure that they are able to fulfil their design life fully loaded.

    Materials and furnishings

    All materials used for the body also have to be carefully selected as weight is always an issue, as is rigidity, particularly in the case of an SNG vehicle.  Therefore the designer is always looking for the strongest, lightweight solutions within the allocated budgets.

    Since these vehicles are often operated in areas of high electromagnetic fields and can be subject to CE testing, metal skinning is usually compulsory.  Sometimes, this extends to metallic fingers on doors and lockers to give maximum isolation. 

    The local environment can also have an impact on the choice of materials as extra insulation will be required in areas of extreme heat or cold. Furthermore, wood-based materials are to be avoided where termites are active —otherwise the OB van can literally be eaten from beneath the operator’s feet.

    Operational use

    Clients will often have clear ideas as to the layout of the vehicle being built. Their style of working will dictate who needs to see what and who needs to be in their line of sight. It will then be the role of the systems integrator to design the necessary compartments to achieve the isolation and lines of contact required. Expanding sides are now commonplace for trailers, and to a lesser extent, for rigid trucks. This is particularly necessary for the production area to achieve the necessary viewing distances and angles to the sometimes vast monitor stacks and to realise the spacious feel, which the operators have come to expect in a fixed production control room.


    Flexibility is the key to the success of any OB vehicle. Large trailers particularly have to cover events ranging from fast action sports, dramas, concerts right through to news incidents – all of which present different production requirements. Therefore, sections of the trucks, such as monitor stacks must be easily and quickly configurable. Likewise, the camera control positions must allow for few operators to control many cameras or many camera operators to work in conjunction with a master control position. Furthermore, the VT area may require its own VT director operating on an M/E bus of the main vision mixer or on a completely separate vision mixer. All of these different styles of operation have to be accommodated in the one design.

    Power sources

    Powering these vehicles can present a unique set of problems – but again, require different devices for different purposes. In the smaller vehicles, the choice is between a number of different options such as shoehorning in a separate generator with attendant space, noise and weight problems, fitting a vehicle-engine-driven generator (even more of a squeeze) or running from batteries/inverter.

    The latter offers a major advantage in terms of noise for drama coverage however can only offer power for a limited time.
    Many destinations, including the UK, may require a mains isolation transformer with the requirement to double insulate the components before the first protection device. Automatic voltage regulators are often needed, as are UPS systems to cover time between mains failure and generator start-up.  However, a common feature of all power related equipment is their excessive weight which as we have noted above is a key consideration for the build out of any vehicle.

    Climate control

    Keeping the equipment and occupants cool in an OB van is another common challenge. Solutions range from an engine-mounted compressor on a small SNG vehicle to a large water-based chiller system for larger trailers.

    There is little doubt that a commercially available, off-the-shelf unit can offer significant advantages in terms of cost, reliability and ease of maintenance. However, they are rarely quiet enough to satisfy the most demanding requirements and have limitations in their mounting locations. 

    As with any form of air-conditioning, the art is often in obtaining the correct distribution of feed and return air to ensure that the equipment is maintained at the correct temperature, without any hotspots, while at the same time ensuring that the operators are not too cold.

    The Equipment

    Having chosen the wheels, frame and shell, powered and cooled the vehicle, then comes the expensive part — filling it with the most robust and flexible equipment and cables to meet the customer’s exacting needs.

    Many broadcasters continue to commission HD-ready vehicles with an HD-infrastructure and SD components that can be easily upgraded at a later stage.

    Most vision systems are based on HD-SDI, although MHz is still occasionally required to build a PAL system. Most systems are still traditional — made up of the standard building blocks which have been used since MHz first began building vehicles. It is only the reductions in cost, size, weight and power consumption of these individual building blocks that has today allowed even the smallest editing vehicles to be equipped with facilities which would have been the envy of the most affluent facilities manager several years ago.

    Recording systems too have changed dramatically and today, many vehicles are fitted with disc-based recorders. The original fears that the harsh environment where these vehicles were operating would play havoc with the delicate discs have proved to be unfounded.

    Today, few decisions can be made concerning audio without the consideration of Dolby 5.1 surround sound.

    However, as with any technology roll out, the implementation of advanced audio processes brings with it a number of challenges. For instance, creating a suitable environment for mixing 5.1 signals and the placement of the speakers can often be awkward in an OB vehicle. Often, the problems are related to fitting an audio mixer across the width of the vehicle wider than road regulations allow. Elaborate trim is often dispensed with and clever hatches devised to achieve what appears to be impossible during the first design meetings.

    Talkback and intercom systems are at the heart of any OB situation and their value cannot be underestimated. These generally range from the communication systems with links via satellite and GSM telephones, to sophisticated, software configured talkback systems with large telephone exchanges and phone-in circuits.

    On-board IT infrastructure and control systems

    Increasingly, the most complex area of a production OB vehicle is that of control and monitoring. Even in the smallest SNG vehicle, computer-based equipment is fitted to enable an inexperienced operator to control and configure the uplink equipment from a simple panel. In large production vehicles, there is often a computer network connecting PCs and equipment, allowing for rapid reconfiguration of all the major hardware in the system for the production side of the vehicle. Additionally the client may also require a separate IT network and terminals for all its IT operations.

    New or refurbished?

    With the current global economic downturn, some broadcasters are looking at alternatives to new build.

    Those keen to see a clear upgrade path for their HD implementation together with an ROI are looking at a phased refurbishment plans for their vehicles. Key considerations for refurbishments include staged SD to HD conversions, the upgrade of audio production to Dolby 5.1 and suchlike. However, a refurbishment plan can also pertain to the fixtures and fittings which may have become worn over time — particularly if the truck has been leased to third parties.  In the current economic climate, where emphasis on ROI is crucial, this phased approach provides broadcasters with an opportunity to use their budgets productively and efficiently.  

    It is clear that there are a number of key considerations to be made when considering the build out or refurbishment of any production vehicles. It is often said that no two systems are identical, and this is very true in the integration of OB vehicles. Even with the vast experience of MHz’s system designers and coach builders, every new project presents its own challenges. We are still waiting for the project requirement to come along when we will be able to return to our dusty archives, pull out a handbook and sit back whilst the OB van builds itself.

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