PC refers to close contact with physical contact
SPC refers to super physical contact,
UPC refers to super physical contact.
The return loss specified by the PC, SPC and UPC industry standards is -35dB, -40dB and -50dB, respectively. (Return loss is how much light is reflected by the end face of the connector. The smaller the return loss, the better. Of course. You can also say that the larger the return loss value, the better, regardless of the previous negative sign). Different connectors cannot be mixed in principle, but the fiber ends of PC, SPC and UPC are flat, the difference is in the quality of the grinding, so the mixing of PC, SPC and UPC does not form a permanent for the connector. Physical damage.
APC is completely different, its face is ground to an angle of 8 degrees, which is to reduce reflection, its industry standard return loss is -60dB. The APC connector can only be connected to the APC. Since the structure of the APC is completely different from that of the PC, if the two connectors are connected by a flange, the fiber end face of the connector is damaged. The method of connecting APC to PC: realized by PC to APC converted fiber jumper. It should also be noted that the APC connector is usually green (and the yellow fiber is just a single mode fiber), and the tilt of the fiber end face can be seen by the human eye. The PC connector is usually blue. Therefore, in order to avoid confusion in the use of connectors during the experiment, the APC connector should be uniformly required. The FC/PC FC/UPC FC/APC can be connected in a mixed manner, and the signal attenuation is not very large. The insertion loss according to the national standard should be less than 0.5 dB. The application mainly depends on the type of the adapter. Generally, the communication ODF frame uses more FCs, the device optical port uses more SCs, and the ST has more LANs and broadcasts.nt-faJsM��6