Duplex fiber and polarity
In the application of 10G Optical fiber, two optical fibers are used to realize two-way transmission of data. One end of each optical fiber is connected to the transmitter and the other end is connected to the receiver. Both are indispensable. We call them duplex optical fiber, or duplex optical fiber.
Correspondingly, if there is duplex, there is simplex. Simplex refers to transmitting information in one direction. At both ends of the communication, one end is the transmitter and the other end is the receiver. Just like the faucet at home, the data flows in one direction and is not reversible. (of course, there are misunderstandings here. In fact, optical fiber communication is very complex. Optical fiber can be transmitted in two directions. We just want to facilitate understanding.)
Back to duplex fiber, TX (b) should always be connected to RX (a) no matter how many panels, adapters or optical cable sections there are in the network. If the corresponding polarity is not observed, the data will not be transmitted.
In order to maintain correct polarity, tia-568-c standard recommends A-B polarity crossing scheme for duplex jumper.
MPO/MTP fiber polarity
The size of MPO/MTP connector is similar to that of SC connector, but it can accommodate 12 / 24 / 16 / 32 optical fibers. Therefore, MPO can greatly save cabinet wiring space.
The three polarity methods specified in TIA568 standard are called method A, method B and method C respectively. In order to meet the TIA568 standard, MPO/MTP backbone optical cables are also divided into through, complete crossing and pair crossing, namely, type A (key up – key down through), type B (key up – key up / key down key down complete crossing) and type C (key up – key down pair crossing).
As shown in the picture below:
Currently commonly used MPO/MTP patch cords are 12-core fiber optic patch cords and 24-core fiber optic patch cords, but in recent years 16-core and 32-core fiber optic patch cords have appeared. Nowadays, more than 100-core multi-core jumpers are coming out, and the polarity detection of multi-core jumpers such as MPO/MTP becomes very critical.
Post time: Dec-16-2021