Bird Technologies SK-4000-TC-Manual - Manual (Page 34)

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Interpreting the Fault Location Measurement
The graph below shows a typical Fault Location measurement for an antenna
system. The table lists typical component return losses.
Figure 13 Fault Location Measurement Screen
Typical Component Return Loss
Antenna at Resonance -14 dB
Connector -25 dB
Jumper -35 dB
Lightning Protector -25 dB
Transmission Line -30 dB
Each connector or jumper will show as a spike. If it is larger than the typical
value, check the connector for damage.
Spikes where there are no components represent faults. Note the distance and
check the line at that point for damage.
The largest spike is usually due to the antenna. Typically the trace after the
antenna can be ignored.
If a selected cable length that is less than the total length of the cable system,
the trace might show a spike that is not really a fault, but rather an echo from
the remaining portion of the cable that is beyond the length chosen. Such a
spike is known as an alias.
Note: To avoid aliasing, always set the measurement distance to a7
value that is a few feet or meters greater than the entire length of the
cable system.
A large spike (fault) near the SiteHawk Analyzer will mask other faults farther
away. When a large spike near the Site Analyzer is found, fix it and then repeat
the Fault Location measurement.