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Chapter 11 Testing with SmartIDs
OneExpert DSL User's Guide
22052280, Rev. 015 April 2019 168
For any given coax cable, the coax map test locates each item and pres- ents the results in an
easy to read table. The table indicates the location of items in terms of a length in feet, from
the test instrument. The table also indicates the return loss at each item in dBrl.
If possible, the OneExpert will also identify items such as opens, splitters, barrels, or splices
based on TDR measurements performed on the cable. In some cases, based on reflection
characteristics, the test set will indicate the presence of bad splitters. If unusual cable
characteristics are measured, the OneExpert will indicate an “unknown” item in the cable.
If the number of legs on a splitter are different than the number of RFIDs, a warning appears.
If the OneExpert is used to measure a home-run cable, it will indicate an 0 dBrl open, and the
full length of the cable.
TROUBLESHOOTING TIP:
If the results table indicates four or more events, it may
indicate a situation where a complex cable topology is causing
multiple reflections. In this case, measurement accuracy can be
improved by performing step by step sectionalization starting
with the first item in the table.
The following shows several cable topologies on the left and the corresponding coax map table
on the right. The dBrl level at each splitter will be relatively low and depend on the quality of
the splitter. Lower return loss indicates a better splitter.