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OTDR – Practical Tool for Testing Optical Cabling


For error-free transmission via optical fibers, it is necessary to observe the limit of the optical path parameters. The most important parameters of optical routes include (Insertion Loss), Optical (Return Loss) and (Reflectance) of individual components on the route.

In practice, the OTDR - optical reflectometer is the most suitable for measuring and evaluating these parameters

OTDR – (Optical Time Domain Reflectometry) optical pulse reflectometer method for measuring and analyzing optical paths. It is important for the measurement and certification of optical cabling, for the installation and servicing of optical routes. It is based on Rayleigh scattering, in which part of the transmitted light pulse returns to the transmitter as it passes through the optical fiber. This weak, backscattered signal is enough for OTDR to evaluate distance, power loss and reflections on the route. It can measure length, attenuation of fibers, cable sections, components, reflections from these components and thus provide a number of other practical information about the route.

We just have to realize that OTDR does not measure the actual attenuation of the route, it only measures backscatter and reflections along the route. Therefore, OTDR is sometimes referred to as a backscatter meter, and we see only apparent path attenuation on the reflectogram curve. The apparent attenuation of the route is affected not only by the actual attenuation, but also by other fiber parameters, such as the diameter of the fiber core. On the apparent attenuation curve, we can then see the gain instead of the loss in the optical connectors or connectors. At the same time, no energy is amplified in the connector, only the section of fiber behind the connector scatters the light more, and on the reflectogram it looks like a gain in the connector. Similarly, multiple reflections of an optical pulse create ghosts, creating a false impression of connectors where they are not.

Nevertheless, the optical reflectometer is the most widely used cable tester. Especially in the automatic measuring mode iOLM intelligent Optical Link Mapper is becoming more and more popular for beginners and experienced technicians.

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iOLM (intelligent Optical Link Mapper)
iolm

Various variants of optical reflectometers are available for measuring optical paths using the OTDR (Optical Time Domain Reflectometry) method. From devices for measuring short routes of structured cabling to long-distance routes of 150 km and more. In addition, for cabling systems, it is necessary to distinguish OTDR for measuring either multimode MM fibers or single-mode SM fibers. The device should be selected with regard to the parameters and structure of the optical networks we want to test.
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You can visit the OTDR configurator for easy selection :

http://www.otdr-iolm.eu/

For more information :

https://www.profiber.eu/cz/merici-technika-opticke-komunikace-a-optoelektronika/opticke-reflektometry-otdr/

https://www.profiber.eu/cz/merici-technika-opticke-komunikace-a-optoelektronika/software-2/exfo-intelligent-optical-link-mapper-iolm/