Fiber management in broadcast networks

For years, television broadcasters have relied on coax cable to route video and audio control signals and RF around their facilities. Coax has proven
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Good cable management ensures that the fiber networks of today are ready for tomorrow's higher-bandwidth applications. Pictured: ADC's FL2000 fiber management system.

For years, television broadcasters have relied on coax cable to route video and audio control signals and RF around their facilities. Coax has proven itself to be easy to work with and reliable.

However, as the television broadcast business evolves from a single analog channel to a digital world, the industry is re-evaluating the role of coax. In its place, fiber-optic cable is emerging as a logical solution for next-generation television signal routing, where greater bandwidth is needed to accommodate HD signals and multicast SD channels.

As these applications drive fiber into more networks every day, many broadcasters' deployment strategies overlook one major consideration. Good cable management practices are the key to an effective fiber network, allowing for flexibility, fluid change, easier network maintenance and configuration and, most importantly, growth. When a broadcaster uses good cable management from the start in its fiber network, the network grows more quickly. Good cable management practices also ensure that the fiber networks of today will be ready for the higher-bandwidth applications of tomorrow.

Guiding the way

ADC's family of fiber infrastructure solutions for broadcasters was engineered with these concepts of efficient cable management in mind. They make fiber networks less susceptible to accidental damage or network problems, quicker to install, less expensive to own and operate over the long haul, and easier to expand as needs grow.

The infrastructure systems address the following items, each critical when deploying a fiber network in a broadcast environment:

  • Bend radiusAt turns in fiber runs, maintain a 1½-inch bend radius. Tighter bends may cause microbending of individual fibers that allows light to escape the signal path, resulting in signal attenuation. More severe bends can break fiber strands completely, resulting in signal loss.
  • Cable troughingUsed to route fiber-optic cable, troughing systems provide a protected pathway for fiber to traverse spans between rooms and equipment racks. Troughing systems such as the ADC FiberGuide system keep fiber separate from coax cable; protect it from out-of-tolerance bends; and promote neat, easily accessible runs.
  • Vertical cable protectionAllowing fiber to hang unprotected from the back of equipment can be a recipe for disaster. Exposed cables are easy to snag accidentally with a wandering hand or foot, which can result in damage to the connector or fiber itself. Additionally, over time, the weight of hanging fiber can cause bends outside the acceptable limit and damage the fiber. Proper vertical cable management in panels or equipment bays provides adequate support, cable protection and a transition from the vertical run to the back of the equipment that does not damage the fiber.
  • Slack storageBesides the ability to tidy up the look of a facility, the proper storage of slack patch cords allows station engineers to work in equipment racks free from the fear that a false move might accidentally do harm. Also, having a dedicated slack storage system for patch cords enables users to specify a single patch cord length for the entire plant. Proper slack storage means engineers can use a 5-meter patch cord without fear that dangling excess fiber will be damaged. Proper slack storage also alleviates worries about the patch cord being too short if changes need to be made quickly. Slack storage systems can take many shapes — from integral storage compartments in stand-alone termination cabinets to 19-inch, 1RU trays, such as the ADC Fiber Management Tray. But the common thread among all of these systems is that extra patch cord lengths are stored neatly, protected from damage and aren't exposed to accidents that can negatively impact the ability of a station to earn revenue.
  • Cable pile-upIn horizontal fiber runs, it is unacceptable to allow a pile of fiber cable exceed two inches. Beyond that point, the weight of the bundle will surpass the crush tolerance limit of the fiber at the bottom of the stack, and result in microscopic damage and signal attenuation. Look for products that have horizontal routing paths that ensure cable pile-up is not an issue.
  • LabelingDevelop good labeling practices. Know where fibers originate and terminate by using products that have adequate designation space. Doing so will reduce maintenance time and the likelihood that a maintenance tech will make hasty decisions on fiber routing that can lead to a rat's nest of cable and patch cords.
  • Future proofingWhen planning rack configurations with a given number of terminations to accommodate a relatively low number of fibers for today's requirements, don't forget the future. A fiber path that easily supports 12 fibers today may be inadequate to support the 200 fibers that will be needed in a couple of years. Planning up front for the future can save the expense of ripping out outgrown capacity down the road.

Tying it all together

Proper cable management is critically important to the successful conversion of television broadcasters from coax to fiber. The fact that a single fiber may transmit mission-critical signals, such as revenue-generating commercials and programming, underscores the importance of taking the steps necessary to manage fiber's installation and use.

Joy McKnight is a product manager for ADC.