Autotest
Autotest Results for Twisted Pair Cabling
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Propagation Delay and Delay Skew
Propagation delays are the times taken in nanoseconds for a test pulse to travel the
length of each cable pair.
Delay skews are the differences in propagation delays between the shortest delay,
which is displayed as 0 ns, and the delays of the other cable pairs.
The propagation delay and delay skew results show a limit if the test is required by
the selected test standard. If the test is not required, the results always show
PASS.
Characteristic Impedance
The characteristic impedance test determines the approximate characteristic
impedance of each cable pair.
Note
Impedance measurements require a cable at least 5 m (16 ft) long.
Cables shorter than this length will always pass the impedance test.
A PASS result means that the measured impedance is within the specified limit
for the selected test standard. A FAIL result means that the measured impedance
exceeds the specified limit, or an impedance anomaly is detected.
A Warning result means that the measured impedance exceeds test limits, or an
anomaly is detected, but the characteristic impedance test is not required by the
selected test standard. The warning result causes a warning to appear as the test
summary result in printed reports.
The test tool reports an anomaly if 15 % or more of the test signal is reflected.
Press F to see where the anomaly was detected. The HDTDR test results show
both the location and size of the anomaly.
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