Why Do You Need OTDR Launch Box?

Optical time domain reflectometer (OTDR) is a necessary fiber optic testing tool which use light backscattering technologies to analyze the optical fiber performance. It can test the light loss and locate the breaks, splices and connectors in fiber optic network. However, OTDR has “dead zone” which can affect the testing result if proper measure is not taken. To overcome the limitation of OTDR dead zone, OTDR launch box is being used. This post will introduce OTDR launch box for your reference.

Basic of OTDR Launch Box

OTDR launch box, according to its function and working principle, has a lot of other names, like dead zone box, pulse suppressor, fiber ring, fiber optic launch cable, etc. How can OTDR launch box minimize the effect of OTDR dead zone during fiber optic testing? The following explains the detail.

The dead zone of OTDR, caused by high return level of reflection and affected by the pulse width, might extend hundred meters from the OTDR. Full length of optical fiber is suggested to use before the optical fiber under test. Thus, the receiver of the OTDR can have enough time to settle. OTDR launch box, which is actually a long spool of optical fiber inserted between the fiber under test and OTDR, can ensure that the OTDR dead zone happens in the OTDR launch box (shown in the following picture). Then, the fiber optic link under test won’t be largely affected by the OTDR dead zone.

OTDR launch fiber to Switch panel connection

OTDR Launch Box Usage Guide

The OTDR launch box comes in various packages. The box-design is the most commonly used one with the advantage of durability. It has a long spool of optical fiber with a pigtail on two ends. One of the pigtail is for input, which is used to connect with the OTDR, the other pigtail on the opposite end is for output, which is used to connect with the optical fiber under test. After connecting the input end and output end to the corresponding port, the OTDR launch box can be used to test the attenuation of the fiber link.

The using of OTDR launch boxes seems really easy. However, the handling of them should be careful. If you want to get accurate test result of the fiber link, the length of the optical fiber inside the OTDR launch box should be long enough to cover the whole dead zone. OTDR launch box is like fiber optic cables, it has different types. And one cannot be used in all fiber link test. The following will tell you how to select OTDR launch boxes.

Which OTDR Launch Box Fit Your Applications?

The selection of OTDR launch box is like selecting fiber patch cable. You should basically consider about the fiber type, connector type terminated on pigtails and the polishing type of the connectors. Another important factor should be considered is the length of optical fiber of OTDR launch box as above mentions. The optical fiber of OTDR launch box should be longer than the dead zone. Thus, most of fiber OTDR launch box can support hundreds or thousands meters.

OTDR Storing case

After inserting the OTDR launch box between the OTDR and fiber under test, the affection of the OTDR dead zone can be minimized effectively. The handling and selection of OTDR launch box should be careful. If you need more information about OTDR launch box, kindly contact ics@suntelecom.cn for more details.

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