Interpreting the Distance to Fault (DTF) on a SiteHawk

Distance to Fault measurements (DTF) have two factors, distance and reflection. The x axis shows distance, and the y axis shows reflection. The lower the reflection at any given distance, the less affect it will have on your signal at that point. If there is a fault at some point in your measured signal path, the DTF measurement will show a high level of reflection at that point. The SiteHawk can make two types of DTF measurements, DTF_RL for reflection measured in return loss (RL), and DTF_SWR for reflection measured in standing wave ratio (SWR). 

In general, reflections under -14 dB (RL) are acceptable for most applications. Here are some typical return loss values for some common components. DTF_SWR will work the same way, but the reflection will be measured in SWR. 

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. 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.

Note: If a maximum distance less than the total length of the cable system is selected, the trace will not show the end of the cable system (antenna). To display the full cable system always set the maximum distance to a value that is a few feet or meters greater than the entire length of the cable system.