Distribution frame
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In telephony, a distribution frame is a closet or area set aside which contains equipment which multiplexes users' transmission mediums over a higher-capacity medium. A main distribution frame multiplexes many DSL lines over a larger cable such as fibre, for example.
In broadcast engineering, a distribution frame is a location within an apparatus room through which all signals (audio, video, or data) pass, with the ability to arbitrarily route and connect sources and destinations between studios and other internal and external points. Connections can either be soldered, or made using terminal blocks. Because the frame may carry live broadcast signals, it may be considered part of the airchain.
Newer digital mixing consoles can act as control points for a distribution frame or router, which can handle audio from multiple studios (even for multiple co-located broadcast stations) at the same time. Multiple smaller frames, such as one for each studio, can be linked together with fibre-optics (which also helps eliminate ground loops), or with gigabit Ethernet. This has the advantage of not having to route dozens of feeds through walls (and sometimes floors and ceilings) to a single point.
Distribution frames for specific types of signals often have specific acronyms:
- ADF - audio distribution frame
- DDF - digital distribution frame
- VDF - video distribution frame
- ODF - optical fiber distribution frame
Distribution frames can often grow to extremely large sizes. In major installations, audio distribution frames can have as many as 10,000 incoming and outgoing separate copper wires. (Balanced audio signals require two wires plus earth ground for each signal).