User Manual

114 Part 004071A revision 00b August 6, 2003
Amosphere NPM Installation Procedures (MMDS)
Measuring the Distance to a Fault
Distance to fault (DTF) is a measurement of VSWR or return loss based on
distance. A DTF test indicates the distance to a short, open, or load. Perform a
DTF test whenever a VSWR test reveals that the antenna system is not operating
within specifications.
To accurately interpret the results from a DTF cable sweep, you need to know
the lengths of your cables and the location of any devices or connectors attached
to those cables. Comparing the results of the test with the layout of your antenna
system will help you to determine if problems are caused by faulty devices,
connectors, or cables.
 To measure the distance to fault
1 Power on and calibrate your cable sweep analyzer.
2 Power off the RFSS module connected to the RF equipment you want to test. See
page 116 for a list of circuit breakers.
3 Carefully disconnect the RF equipment and cables you want to test.
4 Connect the cable sweep analyzer to the equipment and cables you want to test.
NOTE: Be careful not to damage any cables or connectors
when connecting the analyzer to the RF equipment.
5 Perform the cable sweeps.
See the documentation that comes with your analyzer for information about
performing the cable sweep and interpreting the results.
6 Document the results from the cable sweeps according to the MOPs of your site.
Keeping records of periodic cable sweeps will make troubleshooting future
problems easier.
7 Carefully disconnect the analyzer from the RF equipment.
8 Reconnect the RF equipment and cables back to the RFSS module.
If any of the connectors are outdoors, ensure that they are resealed according to
the procedures of your site.
9 Power on the RFSS module. See page 116 for a list of circuit breakers.
installation.book Page 114 Wednesday, August 6, 2003 6:06 PM