Table of Contents
Advertisement
User Manual
Airbridge cBTS3612 CDMA Base Station
III. Lightning arrester (Optional)
When the cBTS3612 is configured for 1900MHz band, the lightning arrester is
necessary, but for the other bands, it is not necessary.
The lightning arrester is used to prevent damage of lightning current to the antenna
and feeder system. Usually, there are two kinds of lightning arresters. The first type
uses the microwave principle to conduct the low frequency lightning current to the
ground so as to sink the current. The second one is a discharging tube, when the
voltages at both ends of the discharging tube reach a certain value, the tube
conducts to sink the large current. The second technique is used in cBTS3612.
Lightning arrester should be installed close to the BTS cabinet, for details, please
refer to cBTS3612 Installation Manual.
IV. Tower-top Amplifier (Optional)
When the cBTS3612 is configured for 1900MHz band, the tower-top amplifier is
optional, for the other bands, it is not necessary.
Tower-top amplifier is used to further improve the signal quality. Normally it is
installed close to the antennas, consisting of triplex filter and low noise amplifier.
The triplex filter is actually a device composed of two duplex filters.
Signals from the antennas first pass through the triplex filter to filter out the out-band
interference, then the low noise amplifier amplifies the weak signals. Finally the
amplified signals are sent over the low loss cable to the BTS.
The purpose of the tower top amplifier is to enhance the receiving sensitivity of the
base station. So the tower-top amplifier is required to have a low noise coefficient.
The power of the signals received on the antenna varies greatly with the distance
between the MS and the base station. This requires that the tower- top amplifier
have a greater dynamic range.
Besides, the tower-top amplifier also has the by-pass function in case of DC power
failure.
The DC power supply of tower-top amplifier is fed through the center conductor of
the receiving feeder by DDU. Since it is an outdoor device, so a reliable waterproof
sealing is required.
The tower-top amplifier can operate under -40
o
o
C~60
C.
2-46
System Description
2 Hardware Architecture
Advertisement
Table of Contents
