A loopback test is really a hardware or software method which feeds a received signal or data to the sender. It is actually used being an aid in debugging physical connection problems.
Fiber optic transceiver will be the fundamental part in every fiber optic communication network equipment. Its function is identical to your computer’s Ethernet Card. (although almost all modern computers integrate it around the motherboard, not as a different PCI card anymore)
Fiber optic transceiver has two ports, a transmitter port along with a receiver port. The direct attach cable port sends out laser signal to some linked transceiver as well as the receiver port receives laser signal in the other transceiver.
On fiber optic transceiver manufacturing floors and in R&D labs, we usually utilize a fiber optic loopback module to make sure that the transceiver is working perfectly as designed as opposed to using another transceiver as the partner.
Basically exactly what the loopback module does is directly routing the laser signal in the transmitter port returning to the receiver port. Then we can compare the transmitted pattern with the received pattern to make certain they are identical and have no error.
Typically the most popular types of transceiver module are SC, LC and MTRJ connector types. But each connector type is split again by fiber type, connector polish type and attenuation.
Each connector type can be obtained for 3 fiber types. They are 50/125um multimode, 62.5/125um multimode and 9/125um single mode.
Only PC polish is offered for multimode type fibers. But also for single mode fiber, two connector polish types are offered: UPC polish and APC polish.
Along with fiber type, working wavelength is definitely the other important aspect for picking the proper fiber optic loopback module for your specific application. Available wavelengths are 850nm, 1310nm dexhpky91 1550nm. 850nm and 1310nm are for multimode applications and 1550nm is for single mode applications.
You may specify just how the signal power level should be reduced from the loopback path. This is because the receiver port cannot handle quite high power. And in the real world fiber optic cable, you will always find attenuations introduced by fibers, equipment and physical environment. And so the transmitter power is attenuated to some safe level from the network before reaching one other receiver.