A loopback test is actually a hardware or software method which feeds a received signal or data back to the sender. It really is used for an help with debugging physical connection problems.
Fiber optic transceiver will be the fundamental part in any fiber optic communication network equipment. Its function is identical to your computer’s Ethernet Card. (although nearly all modern computers integrate it around the motherboard, not as a separate PCI card anymore)
Fiber optic transceiver has two ports, a transmitter port and a receiver port. The direct attach cable port sends out laser signal into a linked transceiver as well as the receiver port receives laser signal through the other transceiver.
On fiber optic transceiver manufacturing floors and then in R&D labs, we usually utilize a fiber optic loopback module to confirm the transceiver is working perfectly as designed instead of using another transceiver as its partner.
Basically exactly what the loopback module does is directly routing the laser signal through the transmitter port back to the receiver port. Then we can compare the transmitted pattern with the received pattern to make sure they are identical and have no error.
The most popular forms 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 is accessible for 3 fiber types. They are 50/125um multimode, 62.5/125um multimode and 9/125um single mode.
Only PC polish is accessible for multimode type fibers. However for single mode fiber, two connector polish types are offered: UPC polish and APC polish.
As well as fiber type, working wavelength is definitely the other important aspect for choosing the proper fiber optic loopback module to 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 are able to specify how the signal power level must be reduced from the loopback path. The reason being the receiver port cannot handle very high power. And in person fiber optic cable, you will always find attenuations created by fibers, equipment and physical environment. And so the transmitter power is attenuated into a safe level from the network before reaching one other receiver.