User's Manual Part 1

Tech-X Flex User Guide - Firmware v06.50 Tech-X Flex
®
(NG2)
4-8
Intro
Overview
Wi-Fi
Ethernet
System
IP/Video
MoCA
RF
Specs
Pair Skew For each pair, the difference in signal propagation time; that is, the time required for
an electrical signal to traverse the respective loop. Ideally, all pairs associated with a
common signal should have identical or very close propagation times, because a
large skew can disrupt high-bandwidth signals with a low tolerance for timing
variations. The primary causes of skew include differing conductor lengths due to
inconsistent twist ratios and differing insulation types.
The skew results are presented in nanoseconds (ns) and are relative to the pair with
the shortest propagation time. The pair with the shortest time shows a skew of zero
(0), while the skew of each other pair represents the additional length of time
required for its respective propagation.
Industry practice varies with regard to the maximum amount of skew that is
acceptable. Additionally, the type of signal, length of cable, and other factors
influence that determination. For these reasons, it is beyond the scope of this
document to provide recommendations on acceptable skew values.
Cable Len For each pair, the estimated 1-way cable length based on a TDR trace. This value
normally indicates the end of the pair, or possibly the first short or open. Note that:
• The maximum measurable cable length is approximately 656 ft. (200 meters).
• At a minimum, the accuracy may deviate by +/-7 ft. (+/-2 meters).
Cable Test
Result
For each pair, a general pass/fail recommendation based on the following two TDR-
related analyses:
• Maximum Peak Check - The TDR trace is analyzed for the highest interim
“peak,” where a peak is analogous to an upward rise in a standard graphical TDR
result. A peak typically occurs when the TDR pulse encounters a point of high
impedance, causing a larger reflection. Internally, the unit applies a threshold to
determine the amplitude necessary to indicate an unacceptable peak.
• First Peak Check - Similar to the maximum peak, the unit sets a different
threshold to determine the first unacceptable peak in the trace. Note that the first
peak is usually the same as the maximum peak, but may differ.
For each case on each pair, if the respective interim peak is not detected, the test
assumes a proper termination of the pair and reports a status of “pass.” Otherwise,
the test reports the approximate location of the associated impedance change with
suggestions of the possible cause.
Result Description
Preliminary issue - Limited distribution only!