Structured Cabling in a Broadcast Facility

July 2017

Being confronted with a complex nest of cabling, unmarked and undocumented, is the stuff of nightmares for broadcast engineers. Structured cabling design and installation, using standard cabling that can be configured to meet changing requirements, has been adopted in broadcast as it has in ICT to avoid these problems.

dB Broadcast is called upon to advise clients on the best approach to satisfy current and future needs.

Structured cabling has important benefits when installed in a new broadcast facility. It can be installed as part of the building contract rather than by broadcast specialists, and the same type of cable flood-wired throughout a building can carry different signal types for IT, phone, broadcast etc. This all keeps costs down.

Deploying a limited number of different standard cables routed via patching frames makes installations more flexible, and can quickly accommodate additions and developments as infrastructure requirements evolve. Thus a well-designed structured cabling system is an important tool to support enterprise agility and growth.

Designing a structured cabling system increases the Broadcast SI's engineering time, but it saves on SI wiring time. A well managed, unified cabling system can also reduce maintenance costs.

So what are downsides of this apparent panacea? The simple principle of structured cabling is in stark contrast with the complexity of the many options and technical standards that govern its use!

Although the broadcast industry does not have published standards for cable management, it is often implemented better than in the IT world, as there are accepted practices by system integration companies such as dB Broadcast that specify documentation, cable marking at both ends, cable dressing and harnessing.

Structured wiring systems must be carefully designed as they will typically persist beyond 10 years a long time in this era of seismic technology change. Getting the design right requires careful long-range technology trend analysis, and translation into practical requirements for the wiring system. When specifying structured wiring requirements during a recent facility build, dB Broadcast dedicated significant effort to trend analysis. This included working with both traditional broadcast vendors as well as vendors driving cutting edge datacentre design. The long-range analysis was complemented by a detailed audit of the connectivity requirements of the various subsystems within the facility.

A structured wiring system makes use of various kinds of cable. Most commonly CAT5e and CAT6 twisted pairs for shorter runs and lower bandwidth links, and fibre both single mode and multi-mode for longer runs and high bandwidth links. Single mode fibre can handle greater distances and can handle multiplexed signals, however it has traditionally been avoided within datacentres due to the cost of the associated optics. The development of standards such as PSM4 mean that lower cost, high bandwidth single mode optics are emerging, which is starting to make single mode infrastructure more attractive.

dB Broadcast is experiencing demand from clients for a structured cabling solution that satisfies the need for increased bandwidth. 25Gb/s works well for uncompressed live production technology and live/file based UHD workflows. Structured cabling must be carefully specified and designed to deal with this.

Where a client has commissioned flood wiring for a building, to ensure proper usage, dB is often involved in specifying and managing every patch. An essential step is the deployment of a patch management system to avoid that dreaded undocumented nest of cables that no one dares change!

Despite the advantages of the structured cabling approach, it cannot meet all broadcast cabling requirements. An SI will still need to provide local cabling.

A final point: while structured wiring can provide great flexibility to patch anything anywhere, that doesn't mean that you should. The design must be aligned with both the network and broadcast design. This is an ongoing process which often involves translating logical design into physical patching, following a coherent scheme that utilises the structured wiring infrastructure efficiently.

Customers won't thank anyone when they discover that many switch ports they need to access are harnessed at one end of a big row of swing frames, and the rack that their equipment is installed in is harnessed at the opposite end of the row, resulting in congested, unusable trunk channels and another swing frame meme on the Internet.

LINK:	http://dbbroadcast.co.uk/structured-cabling/...
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