Comparison of PC, UPC and APC
PC/UPC/APC means the fiber optic connector cross-section technology. PC is short for Physic Contact, UPC is short for Ultra Physical Contact or Ultra Polished Connector, APC is short for Angled Pressed Connector or Angle Polished Connector.
The major physical difference is the endface geometry. The APC ferrule endface radius is polished at an 8° angle while UPC connectors are polished at a 0° angle.
The back reflection of PC is -35dB while the back reflection of SPC (Super P hysical Contact) is -40dB. UPC's back reflection is smaller than PC's, it's only -50dB, APC has the smallest back reflection of -60dB.
In general, UPC connectors are deployed in transport systems, designed for digital signal transport, while APC connectors are preferred for RF video signal transport. APC connectors are also preferred where there are open ports at the other end of splitters, very typical in FTTP network designs.