An Optical Time Domain Reflectometer (OTDR) is an essential device used by fiber optic technicians for validating the continuity and integrity of optical fiber spans along with identifying and locating physical issues like breaks and degradations that negatively affect signal performance. As OTDRs are complex devices that must be configured properly by the user for each test scenario, classroom training is critical for learning and training purposes, ensuring that technicians are taking the most accurate measurements when using in the field network environment.

Topics: optical fiber, otdr, PON, fiber optic training, fiber lab, network simulation, fiber optic cable

With global connectivity and data consumption rising at an exponential rate every year, the need for robust, faster, and more reliable data transmission is at its peak. Supporting this demand, fiber optic technology is fundamental and critical to delivering high-speed communication services and supporting the modern economy. 

Topics: fiber optic testing, otdr

What is the Dynamic Range of an OTDR?

When certifying or troubleshooting optical fibers in a network using an OTDR, the Dynamic Range is a key parameter of the device that determines the maximum length of the fiber that is observed during a test trace. In more technical terms, it is the distance between the point of the initial backscatter and the noise floor at the end of the fiber under test. The dynamic range value is measured and expressed in decibels (dB) and is essentially an analysis of power levels. OTDRs offering a larger dynamic range value can test longer lengths of fiber compared to those offering a smaller dynamic range value. Therefore, equating a dynamic range value with a fiber distance value is important when evaluating or specifying an OTDR for testing fibers in a network.

Calculating Dynamic Range

At the most basic level, the calculation relationship for equating a dynamic range value to a fiber distance includes three components:

Topics: optical fiber, otdr, optical time delays

Topics: fiber optic testing, otdr, fiber monitoring

Topics: optical fiber, otdr

When fiber optic field technicians need to test the integrity of a fiber optic cable, they use an Optical Time Domain Reflectometer (OTDR) device that identifies and pinpoints issues like breaks/faults and poor splices, while also certifying the cable length.  To find and resolve issues in the fiber cable quickly and efficiently, it’s critical that they not only have a reliable OTDR device, but just as importantly know how to use it properly in terms of selecting the necessary settings and interpreting the results correctly.  This is achieved by receiving thorough training in the classroom prior to heading out into the field.

Topics: fiber optic testing, otdr

The Optical Time Domain Reflectometer (OTDR) is a vital tool for fiber optic testing that can analyze the performance of fiber optic cabling through the use backscattering technologies, as well as identifying and locating connectors, splices, and breaks in fiber optic networks.

However, there is an unwanted phenomenon known as ‘dead zone’ that occurs when using an OTDR, which can cause improper readings if the right steps aren’t taken. This dead zone limitation can be avoided through the use of an OTDR Launch Box, which is what we review in more detail here.

The Launch Box Basics

The launch box, which is also known in the industry as a launch fiber, pulse suppressor, dead zone box or fiber ring, is a device that helps to eliminate the dead zone issue during fiber optic testing significantly. The dead zone is something that occurs when the pulse width changes and causes a high degree of reflection that can cover an area several hundred meters from where the OTDR is located. This results in the OTDR device not being able to detect events or issues in that area.

A term launch box is a box that contains a long spool of fiber that is placed in between the fiber being tested and the OTDR. This provides extra fiber on which the dead zone can occur. This enables the OTDR to now detect events at the beginning of the fiber being tested.

Using Your Launch Box

Launch boxes come in various shapes and sizes. However, all tend to have a robust outer casing to make them more durable. Each end of the fiber is terminated, with one to be attached to the OTDR and the other to the fiber being tested. Once connected to the relevant ports, the test can be run accordingly.

While using an OTDR box is a relatively simple process, you must be sure that it contains a sufficient length of fiber to take account of the entire dead zone or you still won’t achieve a proper reading on your trace and could miss events. Choosing the right OTDR launch box is important, as they can be customized to the specific application or device.



M2 Optics OTDR Sidekick Launch Box Solution



Choosing the Right One

When choosing the right OTDR launch box for your needs, you should approach it in the same way as you would choose a fiber patch cable. Box styles along with features such as connector type, fiber type, and fiber length should all be determined. Furthermore, some launch boxes are available with bulkhead adapters while others provide directly terminated fiber ends.

As mentioned before, a dead zone can cover several hundred meters, so your launch box spool should be long enough to cater for this. It is important to make sure you choose one that suits the job, and your OTDR user manual can provide guidance regarding the expected dead zones.

Learn More


If you would like to learn more about anything else relating to packaged optical fiber solutions, network simulation, and latency/time delays, please get in touch with us at M2 Optics by calling us on 919-342-5619 or, visit our website www.m2optics.com.




Since 2001, M2 Optics has been an established manufacturer and innovator of professional optical fiber platforms for fiber network simulation, latency / optical time delay, training, and demonstration applications. Our customer base includes many of the world's most recognized communications service providers, equipment manufacturers, data centers, web service providers, financial institutions, research institutions, and government agencies.

Topics: otdr

Topics: otdr

An Optical Time Domain Reflectometer (OTDR) is an optical measurement instrument designed to detect faults, splices and bends in optical fiber cables.  It functions by launching pulses of light into the optical fiber and measuring the back reflections created by the faults, splices, and bends.  It can identify the exact location of the fault by measuring the round trip time from the launch to the detection of the reflected returning pulse.  The time is determined by the speed of light in the glass core of the optical fiber.

Topics: otdr