APPENDIX C: ADVANCED CABLING ISSUES (SKEW)
You can measure pair lengths with a LAN cabling tester (TDR) or view pairs by stripping back a small piece of cable and viewing how tightly the pairs are twisted. The most tightly twisted pair is the slowest (longest) and the loosest pair the fastest (shortest). You can also observe relative delays using the test card.
Some cables have a ‘3+1’ construction where three pairs closely match. The fourth pair should be used for data and the other pairs sorted as in the above table. Other cables have a ‘2+2’ construction where there are two sets of dissimilar pairs. Put red and green on one set (tightest) and blue & data on the other.
A suitable
Extender with Skew compensation
In more extreme cases, you should consider using an alternative extender with an
Patch Cable
To obtain optimal video performance with your existing setup, it is desirable to have the green signal as the reference (slowest). This is because the human eye is extremely sensitive to additional green distortion (introduced by delays).
If your system requires a large delay on the green signal, try using a crossover patch cable at each end of the link (instead of straight patch cables to connect to wall outlets). In many cases, the crossover should transfer the delay requirement to the blue signal rather than green. The human eye is much less sensitive to blue distortion and so video quality appears to be improved. The main cable should be wired according to
The alternative ServSwitch™ Brand CATx KVM Extender range (ACU2000 series) has been specifically designed for the extension of high screen resolutions (1600x1200) over long CATx cables (300m). ServSwitch™ Brand CATx KVM Extenders have fully integrated skew compensation and independent control of low frequency (LF) and high frequency (HF) cable equalization.
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