What is OTDR?

What is OTDR?

OTDR is the abbreviation for Optical Time Domain Reflectometer. It is a device that is used to test optical fibers. The gadget works by sending a sequence of light pulses into the fiber and retrieving light dispersed or reflected back along the fiber point from the same end. The fiber is delineated using intense scattered or reflected light. In this article, we will learn about what is fiber OTDR and its related knowledge.


Optical Time-Domain Reflectometer (OTDR)

Working Principle of OTDR

Optical time domain reflectometry is a technique for measuring the reflection of light in the optical domain. The same idea applies to OTDR as it does to radar. Radar is a detection device that use radio waves to determine an object’s range, location, and speed. The transmitter sends out radio waves that are aimed at the target. When these waves hit an object, they are reflected back to the transmitter. These reflected waves are collected by a receiver, which extracts information about the object’s position and velocity.

OTDRs, on the other hand, use lasers rather than radio waves. The laser light passes through an optical fiber, the characteristics of which must be determined. Due to flaws in the fiber, some of the laser signal is reflected back. The reflected light is collected by a receiver on the same side of the transmitter, which extracts information about flaws in the fiber. The backscatter measuring method is also known as this. To understand faults or deformations in the wire, calculates the power of reflected light and plots it on a time graph.

working principle

The Benefits of an OTDR

At any point during the fiber’s operation, the device may discover defects and malfunctions, as well as determine the degree of signal loss. To make a measurement, the OTDR testers only have to access one end of the fiber. The system can take thousands of measurements along the fiber thanks to the technology. It can be used to show a snapshot of the cable‘s operation on the screen as a slanted line sloping down from left to right, with distance on the horizontal line and signal level on the vertical line. From installation to maintenance to fault location and recovery, fiber OTDR tester is widely employed in the fiber optic system life cycle.

If you’re setting up an external industrial network, you’ll need an OTDR to inspect the slices running along the fiber and make sure it’s in good shape. After the splicing is finished, the OTDR tester locates the splice and validates its performance. The OTDR can also identify stress fractures in the cable caused by improper installation (such as exceeding the bend radius). If you need to do any repairs because the cable has been cut, the OTDR will assist you in determining where the cable has been cut and confirming the quality of the repaired splice. On single-mode fiber, where connector reflections must be taken into account, the OTDR fiber tester will quickly identify any issues.

multi-function OTDR

Multi-function OTDR

Where to use an OTDR?

There appears to be a lot of misunderstanding about whether and how to use an fiber OTDR. OTDRs work differently in different scenarios in two major fiber optic applications: outdoor cabling and indoor cabling. Longer off-site cable with several splices require OTDRs, which are typically used to check that the cables were not damaged during installation and that each connection was done correctly. It is used to troubleshoot issues, such as locating a broken cable. Because house wiring has short cable lengths and nearly never includes connectors, OTDRs promise to be a viable alternative to insertion loss otdr fiber testing using light sources and power meters. However, OTDRs are roughly ten times the cost of fiber optic testers.


OTDRs are essential test equipment for finding defects and errors in fiber optic networks, assuring reliable network operation. You’ll be ready to detect and eradicate your fiber incidents once you’ve mastered the OTDR function and how to use it appropriately.

Baudcom offers all types of OTDR. For more information, please feel free to contact us.

Post time: 2021-06-03


Lomoveishiy – Finland

I needed those to connect my PC on the third floor to have internet access in that room, and ISP installed their modem on the first floor only. After dropping fiber patch cables, plugged in all cables into these media converters at both sides, and link came up instantly. Was much easier than I thought!

Raymond – USA

Great experience – units worked straight out of the box – just needed plug in cables and we were done. I also like the possibility to enable jumbo frames, while we do not have a need for this feature at the current moment it’s great to have this option.

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