User Manual
Airbridge cBTS3612 CDMA Base Station
System Description
2 Hardware Architecture
2-60
2.7.3 Lightning Protection for Trunk Line
I. Overview
Three kinds of trunk lines are supported in BTS: 75Ù coaxial cable (E 1), 1 2 0 Ù
twisted pair (E1) and optical fiber. Lightning protection is out of question if optical
fiber is used as the BTS is connected with fiber tail. For E1 trunk line, the BTS E1
surge protector (BESP) on top of the cabinet provides lightning protection.
II. Connection to BTS via E1 trunk line
The connection is shown in Figure 2-30.
BESP
BTS
Transmission
equipment
BCIM
75/120
75/120
Grounding bar of the room
Figure 2-30
Connection to BTS via trunk lines
III. BESP introduction
E1 interface protection of BTS is implemented through a BESP on top of the cabinet.
In consideration of the limited cabinet -top space or the convenience of installation,
two identical BESPs are used, each with 8 pairs (16 PCS) of E1 lightning protection
units, 1 DB37 connector and 2 DB25 connectors, as shown in Figure 2-31.