Introduction
An Optical Time Domain Reflectometer (OTDR) is a crucial tool in fibre optic network testing. It is used to measure the optical loss in the fibre and to identify the location of faults or breaks in the fibre optic cable.
However, OTDRs are not immune to problems that can affect their accuracy and performance. In this blog post, we will discuss the common problems with OTDRs and how you can avoid them.
Types of OTDR problems
OTDR problems can be categorised into several types, including dead zones, event dead zones, reflections, and inaccurate event location.
Dead Zones
This refers to areas in the fibre where the OTDR cannot detect events, which can result in missed faults or incorrect loss measurements.
Event Dead Zones
This refers to areas in the fibre where the OTDR cannot accurately measure the loss or distance of an event, resulting in incorrect measurements.
Reflections
This is when multiple event locations are displayed, leading to incorrect measurements and loss calculations.
Inaccurate Event Location
This is where the location of a fault is not correctly identified, leading to incorrect repair efforts.
Causes of OTDR Problems
There are several factors that can contribute to OTDR problems, including poor connector performance, optical amplifier saturation, improper launch cable, and environmental factors such as temperature and humidity.
Poor connector performance can result in reflections and incorrect event locations, while optical amplifier saturation can cause dead zones and incorrect loss measurements. Improper launch cables can also lead to incorrect measurements.
Environmental factors like shifting terrain or water ingress can affect the accuracy of the measurements, especially if the OTDR is not properly protected or stored safely.
How to Avoid OTDR Problems
To help you avoid OTDR problems, it is important to practice proper equipment maintenance, regular calibration and testing, and the use of high-quality launch cables and connectors. Proper equipment maintenance, such as cleaning and inspecting the OTDR, can ensure that it is functioning correctly and accurately.
Regular calibration and testing can also help to identify any problems with the OTDR. Using high-quality launch cables and connectors can also reduce the likelihood of reflections and incorrect event locations. It is also important to be aware of environmental factors during testing and to take steps to protect the OTDR from extreme temperatures, humidity, and other conditions that can affect its accuracy.
OTDR testing needs to be done in an area free from outside interference, for example away from electric motors, generators, or any other RF sources. Finally, always take multiple readings from both ends of the fibre cable under test and compare the results.
Conclusion
An OTDR is a crucial tool in fibre optic network testing, and it is important to understand the common problems that can affect its accuracy and performance. Dead zones, event dead zones, backscatter, excessive attenuation, reflections, and inaccurate event location are just a few of the problems that can arise.
To avoid these problems, it is important to practice proper equipment maintenance, regular calibration, and testing, and to use high-quality launch cables and connectors. It is also important to be aware of environmental factors and to take steps to protect the OTDR from extreme temperatures, humidity, and other conditions that can affect its accuracy.
By following these steps, you can ensure that your OTDR is functioning correctly and providing accurate measurements.
If you want to learn more about OTDR's, take a look at the range available. If you want to contact or find out more about this blog posts author, Ian Bankhurst, click here.
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