... ST, FC, SC connector4.E1(G.703)interface support 120ohm(RJ-45) and 75ohm(BNC)5.Multi-mode 2KM, signal-mode 20KMCommunication ... -T G.703 protocolE1 signal (BNC) IN, OUT E1 signal(RJ-45) T+, T-, R+, R-, GND Optic fiber signal TX, RX ... -mode 20KM Interface protection 1500V electromagnetism isolate E1 port connectorr120ohm(RJ-45) and 75ohm(Balance) Optic port connectorMulti-mode adopt ST connector ...