... port loop 3.Choice ST, FC, SC connector MODEL7301 Optical Optic Modem converts E1 electrical signal ... SC connector4.E1(G.703)interface support 120ohm(RJ-45) and 75ohm(BNC)5.Multi-mode 2KM, signal ... .703 protocolE1 signal (BNC) IN, OUT E1 signal(RJ-45) T+, T-, R+, R-, GND Optic fiber ... E1 port connectorr120ohm(RJ-45) and 75ohm(Balance) Optic port connectorMulti-mode adopt ST connector, signal-mode adopt ...