Loopback Test – The Least difficult Way For you to Make sure Your own Soluble fiber Optic Transceiver Is Functioning Faultlessly

What is a loopback test?

A loopback test is a components or software program method which feeds a obtained signal or information back to the sender. It is utilized as an help in debugging bodily link troubles.

Fiber optic transceiver loopback check

Fiber optic transceiver is the elementary portion in any fiber optic communication network products. Its function is specifically the identical as your computer’s Ethernet Card. (although almost all modern day personal computers combine it on the motherboard, not as a different PCI card any more)

Fiber optic transceiver has two ports, a transmitter port and a receiver port. fiber optic equipment sends out laser sign to a connected transceiver and the receiver port gets laser signal from the other transceiver.

On fiber optic transceiver manufacturing floors and in R&D labs, we normally use a fiber optic loopback module to confirm the transceiver is doing work perfectly as developed instead of using an additional transceiver as its companion.

Generally what the loopback module does is directly routing the laser signal from the transmitter port again to the receiver port. Then we can compare the transmitted pattern with the received pattern to make confident they are similar and have no mistake.

What varieties of loopback modules are available?

The most well-liked kinds of fiber optic loopback modules are SC, LC and MTRJ connector types. But every connector type is divided once again by fiber sort, connector polish variety and attenuation.

Fiber Sorts

Every single connector variety is offered for a few fiber sorts. They are 50/125um multimode, sixty two.5/125um multimode and 9/125um solitary manner.

Connector Polish Varieties

Only Laptop polish is accessible for multimode type fibers. But for one method fiber, two connector polish sorts are obtainable: UPC polish and APC polish.

Working Wavelength

In addition to fiber type, operating wavelength is the other important element for deciding on the correct fiber optic loopback module for your specific application. Available wavelengths are 850nm, 1310nm and 1550nm. 850nm and 1310nm are for multimode applications and 1550nm is for one manner purposes.


You can specify how the sign electrical power degree should be lowered in the loopback route. This is since the receiver port are not able to manage quite higher energy. And in true life fiber optic network, there are always attenuations introduced by fibers, products and actual physical surroundings. So the transmitter electricity is attenuated to a safe level by means of the network just before reaching the other receiver.

Nevertheless given that you are routing the transmitter immediately back to the receiver, attenuation generally must be included to protect the receiver.

How a lot attenuation should be included relies upon on your transceiver sort and you must choose it by yourself. Thankfully, there are a broad range of attenuation choices offered from 0dB, 1dB, 2dB to 24dB or even more.


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