External Interfaces; Indices - Huawei Airbridge BTS3612A-1900 Technical Manual

Technical Manual
Airbridge BTS3612A CDMA Base Station
The DB25 is a female connector. There are two DB25 connectors, respectively
connected with four E1/T1 cables.
II. Principle of lightning protection
The principle of lightning protection is shown in Figure 2-8.
Core
Lead in
DB25
Sheath
PGND
Figure 2-8 Principle of E1/T1 lightning protection
When the BTS E1 trunk line is struck by lightning, high voltage will arise first on the
DB25 and then spread to the lightning protection units. The lightning protection units
have two protection levels: air discharge tube and voltage limit mesh. The air discharge
tube discharges the high voltage to the ground and lowers it to 600V below. Then the
voltage limit mesh further lowers the voltage to 30V below.

2.7.3 External Interfaces

E1/T1 interface
Interface with the BSC (DB25).
Connection with the BCIM (DB37)

2.7.4 Indices

Bearable surge current: >10kA (common mode), >5KA (differential mode)
Output residual voltage: <30V.
Dimensions: 140mm %120mm (Length%Width)
Chapter 2 Baseband Subsystem
2-16
System Principle
Lead out
DB37