Thursday, August 4, 2011

Patch Cords


Patch cords are used in patch panels to provide the connection between field-terminated horizontal cables and network connectivity devices (such as switches and hubs) and connections between the telecommunications outlets and network devices (such as computers, printers, and other Ethernet-based devices). They are the part of the network wiring you can actually see. As the saying goes, a chain is only as strong as its weakest link. Because of their exposed position in structured cable infrastructures, patch cords are almost always the weakest link.
Whereas horizontal UTP cables contain solid conductors, patch cords are made with stranded conductors because they are more flexible. The flexibility allows them to withstand the abuse of frequent flexing and reconnecting. Although you could build your own field-terminated patch cords, we strongly recommend against it.
The manufacture of patch cords is very exacting, and even under controlled factory conditions it is difficult to achieve and guarantee consistent transmission performance. The first challenge lies within the modular plugs themselves. The parallel alignment of the contact blades forms a capacitive plate, which becomes a source of signal coupling or crosstalk. Further, the untwisting and splitting of the pairs as a result of the termination process increases the cable's susceptibility to crosstalk interference. If that weren't enough, the mechanical crimping process that secures the plug to the cable could potentially disturb the cable's normal geometry by crushing the conductor pairs. This is yet another source of crosstalk interference and a source of attenuation.
Tip 
Patch cords that have been factory terminated and tested are required to achieve consistent transmission performance.
At first glance, patch cords may seem like a no-brainer, but they may actually be the most crucial component to accurately specify. When specifying patch cords, you may also require that your patch cords be tested to ensure that they meet the proper transmission-performance standards for their category.

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