Tower mounted transmission lines are exposed to weather, and will degrade over time.
Lightning can sever a portion of the antenna or damage the in-line lightning arrestor.
Many components can cause problems in a communication system.
Transmission lines are typically the most common failure point.
These common problems can cause unwanted signal reflections.
Poorly tightened connectors and poor environmental seals are exacerbated by acid rain corrosion.
It is much less expensive to monitor individual transmission lines for slight degradation and fix the problem early, before serious damage occurs. Transmitter performance is optimized by eliminating poorly performing components. Hand off anomalies are reduced by eliminating ping-ponging between weak/strong base stations.
Preventative maintenance has another set of benefits even more important than cost. Overall quality is improved giving greater customer satisfaction.
The relative propagation velocity of a coax transmission line is required for distance calculation.The attenuation per foot or meter for the cable is also required in order to compensate for the attenuation versus distance.Likewise the cutoff frequency and waveguide loss are required for DTF, measurements of waveguide transmission lines.Eventually these problems cause intermittent outage and failures at exactly the times they are least welcome, such as during storms or during extreme periods of cold.With DTF available, the root causes of RF problems can be identified.Distance To Fault (DTF) is a performance verification and failure analysis tool used for antenna and transmission line service and maintenance.It uses the Frequency Domain Reflectometry (FDR) measurement technique.This practice may be precipitated by the cable installer, who would likely make the same mistakes on each cable connection.Replacing all the cables frequently is an expensive proposition.The FDR technique uses a swept RF signal instead of TDR DC pulses.FDR is far more sensitive than TDR and can precisely locate faults and degradation in system performance, not just DC open or short circuit conditions.