In Broadcast - May/June 2011 - 34

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SPOTLIGHT
New developments in fibre
by Dick Hobbs
Fibre optic cables have, of course, been around the broadcast industry for many years. But they have traditionally been regarded as a specialist area. The perception has been that installing and making of fibre is a difficult business requiring dedicated skills and equipment. That has led to fibre being largely confined to closed systems for transporting large numbers of signals, from companies like Telecast Fiber and Riedel Mediornet. Outside broadcast cameras use fibre connectivity when very long distances are involved, using a SMPTE standard hybrid cable and connector. When fibre needed to be installed in a facility the job tended to be handed to a specialist contractor, usually from the IT world rather than broadcast. Part of the challenge lay in cutting the fibre to length because it was intolerant of bends so leaving coils of slack in the bottom of a rack was not practical. That is why, according to Chris Smeeton of leading distributor Argosy, one of the most important developments has been the introduction of “bend insensitive” fibre. This uses a special coating on the inside of the cable jacket which reflects the light back into the fibre, greatly reducing the losses. Argosy, which developed one of the first bend insensitive cables, BendBright, in association with manufacturer Draka, demonstrates its capabilities by coiling a length of cable around a pencil. The point, according to Smeeton, is that “it makes patch panels practical, making fibre a real broadcast solution”. The reason that fibre needs to be demystified for broadcast applications is because of the rapid growth in 3Gb/s signals, either for 1080p or for stereoscopic 3D television. 3Gb/s data rates pose huge challenges for co-ax copper cables, and a simple to install fibre solution is required. Making the fibre easy to lay without worrying about bends and kinks is one part of the problem. The other is the perception that fibre is difficult to terminate and, should a cable get damaged, while any competent wireman can solder on a BNC in a minute or two, if it is a fibre then you need to call in an expert. Several manufacturers, including Belden, have now developed simple snap-on connectors. 8mm of the jacket is stripped with a simple tool, the prepared end is inserted into the connector and a clip closed. If the termination is not perfect, the clip can be opened and adjusted a couple of times. “This is perfect for patch cords, and it all makes fibre practical for a wireman,” according to Argosy’s Smeeton. Richard Hutchinson of Optical Cable Corporation (OCC) concurred: “With the advent of bend tolerant fibre everybody is moving towards single mode fibre for HD installations. It has become a common standard, and we have to move to fibre.” OCC works with customers to develop specific applications: when I spoke to Hutchinson at NAB he had been working with a customer on a 36 channel fibre ring system. He also commented on outside

Riedel’s MediorNet system

Belden Connects

broadcast fibre connectivity. “Trucks are being pushed further away from the action, so triax is becoming a problem,” he felt. “Logistically life is changing, with many more cameras in use typically.” He also thought that Europe was ahead of the US in its use of fibre. Bluebell Opticom specialises in developing fibre solutions to specific requirements, either in dedicated boxes or in compact modular frames. “We aim for flexibility,” said Mark Townsend. “We ask the customer what fibre do you want to use – hybrid or four core tactical cable – what connectors do you prefer – Lemo or Neutrik – and what do you want to put down it.” The company had recently developed some special solutions for UK outside broadcast specialist Telegenic, for its 3D unit. This carries the left eye and right eye signals, plus data and GPIs for camera and rig control. Many applications are driven by sport, for instant point of view HD cameras which require transport of a genlock signal and data for tally and control as well as the output video. Telecast Fiber Systems recently launched a new range of point of view camera links, particularly aimed at robotic cameras. The base station module is highly compact, allowing nine links to be housed in a 3U rack

cabinet. Optical power metering is included, and using SMPTE hybrid fibre cables means that the robotic pan and tilt head can be powered over the same cable. MultiDyne is also tackling the challenge of providing a secure connection between a camera close to the action and a truck some distance away. Its Lightbox system, which puts all the connectors and electrical to fibre conversion in a configurable weatherproof case, has recently gained two new models. The first reflects the view of MultiDyne’s Fred Scott that “the trend today is to move as many signals over as few fibres as possible”. The Lightbox 1440 can handle up to 60 feeds, with multiple HD cameras and their viewfinder returns, audio, intercom, GPI, tally and ethernet. The Lightbox II is a second generation compact device, particularly aimed at news and events operations. The units are configurable using the interface cards developed by MultiDyne and which can be used in the industry-standard OpenGear modular system. The latest video card can carry up to 18 HD video channels over one fibre. An innovative approach to connectors comes from Advanced Fiber Products. They have a system, originally
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