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What is an OTDR?

What is an OTDR?

An OTDR or Optical Time Domain Reflectometer is the most powerful piece of fibre optic test equipment for assuring the overall quality of a fibre optic link. It can measure the length of the fibre and the losses of the components all the way down the line. So it is very important that it is set up and used correctly to provide accurate and reliable information.

Learn to use an OTDR

OTT COFI course logoOTDR testing is a very important skill to learn for fibre optics. On OTT’s Certified Optical Fibre Installer (COFI) courses you’ll learn how to use an OTDR properly to measure typical links. The COFI core course is designed for installation and maintenance staff working on core telecom fibre optic networks. The COFI Enterprise course is designed specifically for installation and maintenance staff working on enterprise, datacomms, local area (LAN) networks.

Certified Fibre Characterisation Engineer CFCE course logoOn the Certified Fibre Characterisation Engineer (CFCE) course you’ll master the more advanced OTDR testing that is needed to characterise long haul telecoms fibre/fiber links. You’ll learn how to set up the OTDR correctly to get the best measurements. You’ll learn how to interpret the OTDR traces in order to get all the information you need about losses of the fibre, splices, connectors etc. You also learn how to spot problems such as bends or breaks in the fibre and mismatches in fibre type. You’ll also learn about the benefits of using OTDR trace viewing & processing software. And you’ll also learn to carry out all the other tests, such as Chromatic dispersion and PMD testing, which are needed for full fibre characterisation. A knowledge of OTDR testing is also useful for optical network planners or network architects who may have to analyse OTDR traces and make sense of the information they can provide, in order to make good decisions.

What OTDR do you need?

There are many different OTDRs on the market with quite difference performance and capabilities. OTT recommend that you buy the OTDR with as much dynamic range as you can afford because that will help you to get the best measurements quickly and efficiently.

Below you will find links to major manufacturers of OTDRs, with some example products. This selection does not imply any recommendation by OTT.

AFL Logo

AFL’s range of OTDRs include the low cost FlexTester range for enterprise networks, up to the M710 for metro and core networks.

FlexScan OTDRs are designed to automate test setup, shorten test time and provide simplified interpretation of results. The unit will apply industry-standard or user-set pass/fail criteria and display results using the simplified icon-based LinkMap view. Results can be stored internally or externally.

The M710 Multifunction OTDR is available in both Quad and single-mode models for testing and troubleshooting LAN/WAN, metro, and long haul networks. The M710 features AFL’s TruEvent™ event analysis software which detects, locates and measures network events such as splices, connectors, breaks and macro-bends. Results are presented in the visual result display LinkMap.


EXFO OTDRs include the MaxTester series and high performance OTDR modules that go into the FTB-2 platform.

The tablet style MaxTester 720C is a compact quad unit optimised for singlemode and multimode field testing for data centres, private/enterprise networks, FTTA and fronthaul deployments. It includes a power meter, a visual fault locator, Wi-Fi connectivity and high-resolution inspection capabilities.

The FTB-2, available in a standard or Pro model, is a multi-purpose test platform with two module slots which can take a variety of modules. The FTB-7000 series of OTDR modules offer singlemode and multimode configurations available at several wavelengths. With a touchscreen it is a windows based platform with Wi-Fi, Bluetooth, Gigabit Ethernet, and multiple USB ports for connectivity. The platform is also compatible with EXFO Connect, to offer cloud-hosted services for asset and test data management.

Viavi Logo

VIAVI offer a range of multi-purpose mainframe platforms suitable for engineers installing, maintaining, troubleshooting or monitoring all types of fibre optic networks. These units can be loaded with a very wide range of application specific modules for singlemode and multimode OTDR testing and full fibre characterisation.

Viavi 4000 series OTDR modules can be fitted to the compact MTS-2000 platform, which takes one module, and to the MTS-4000 that takes two modules.

The larger 8000 series OTDR modules go into the bigger MTS-6000 or MTS-8000 platforms.

All Viavi OTDR modules are available with the FiberComplete function that allows a pair of OTDR modules to be used for bi-directional insertion loss and optical return loss testing as well as OTDR testing.


VeEX® develops a variety of test and measurement solutions for next generation communication equipment and networks. The VeEX® FX series OTDR solutions are suited for outside plant environment and complement their VeEX Transmission and Ethernet testing solutions.

Tell me more about the CFCE course

    The Certified Fibre Characterisation Engineer (CFCE) training program is delivered under license by OTT's approved partners in the UK, Ireland and USA. Please complete the form to be put in contact with your nearest partner.

    Please put me in touch with OTT partners offering the CFCE course

    You can also email us if you'd like to provide more details about your enquiry: [email protected]

    Tell me more about the COFI course

      The Certified Optical Fibre Installer (COFI) training courses are delivered under license by OTT's approved partners in the UK, Ireland, South Africa and Oman. Please complete the form to be put in contact with your nearest partner.

      Please put me in touch with OTT partners offering the COFI course

      You can also email us if you'd like to provide more details about your enquiry: [email protected]

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