User Manual

ALLGON SYSTEM AB - Proprietary
Technical Specification for PCS Tower Top Power Amplifier [Allgon 9256]
Preliminary
-
Subjected
to change without notice
Rev.pA0
File: 93651
Page 7 (19) 29 Mar 00
3.2 P
RINCIPLE
O
F
O
PERATION
3.2.1 General
The TTPA has the RX and the TX signal paths separated by means of duplex filter or isolators.
All circuitry for power supply and supervision are included inside the unit.
The TTPA has two ports designated BTS and ANT. The BTS port carries the signals to/from the
BTS rack (e.g. TX-in, RX-out, DC-power). The ANT port will be connected to the antenna. See
figure 2 Basic TTPA Block Diagram.
3.2.2 Transmit Path
The Transmit path incorporates a balanced power amplifier with high linearity. An Automatic
Gain Control circuit (AGC) keeps the gain at a constant level from input to ANT output. TX-path
Bypass is optional.
3.2.3 Receive Path
The Receive path consists of a balanced LNA with very low noise factor. The LNA has a gain
change capability in order to compensate for different feeder losses and optimize the link budget
on each site. RX bypass, which will cut in at power failure or LNA failure, is an optional function.
3.2.4 Power Supply
The Power Supply filters and regulates the input DC power to suit the amplifiers. DC power fed
into the unit on the BTS input connector through the feeder is standard. Separate DC connector
and redundant DC/DC is optional.
Figure 2. Block diagram of the Tower Top Power Amplifier.
EXT.DC
op ti on
CI
&
LP
dB
In pu t Pow er
BTS port
DC /D C 26V
26 V
dB dB
ANT port
Forward
Power
Re ve rse
Power
TX byp ass
dB
RX byp ass
SYSTEM
CONTROLLE
EXT:ALARM
op ti on