In data communications applications, using higher-end products is not often a problem. But sometimes more isn’t better. For instance, you’d probably expect that CAT5e and higher-grade cables would enhance performance. Surprisingly, the opposite is true—CAT5e cable may actually degrade video. This is because many CAT5 video extenders are designed specifically for the CAT5 specs defined by the TIA/EIA-568A or -568B standard.
Higher-level cables have different characteristics and can actually interfere with equipment expecting a true CAT5 transmission.
To reduce electrical crosstalk, CAT5e and CAT6 cables have tighter cable twists—and more of them—than CAT5 cable does. Because of this, the wire distance that an electrical signal has to travel is different for each pair. This doesn’t normally cause a problem when transmitting data, but if you’re sending higher-resolution analogue video signals across long cables, you may see colour separation caused by the red, blue, and green signals arriving at slightly different times.
It’s also important to always use shielded twisted-pair (STP) cable if it’s recommended. Devices that require shielded cable often support high-resolution video, which is very susceptible to electromagnetic interference (EMI) over long distances.
You should make sure that the pairing and pinning of cable connectors meet the TIA/EIA standard, too. Incorrectly wired twisted-pair cable will dramatically impair video quality and possibly prevent correct operation. Do not, for example, use cables paired according to the USOC spec—Pin 1 with 2, 3 with 4, 5 with 6, and 7 with 8.
To ensure optimal video resolution, it’s important to always match your video device with exactly the right kind of cable.