User Manual

The first mixer stage on the CSA amplifier board, which is controlled by a
synthesizer, converts the received frequency down to the IF frequency.
The signal is then filtered by SAW bandpass filters and, not shown in the
figure, amplified before it is fed to the second mixer stage for conversion
back to the original frequency.
The following power amplifier is controlled by the CU. The output gain
can be reduced to avoid instability due to poor antenna isolation.
The output signal from the power amplifier is fed to a combiner, which
combines the signals from the two channels on the channel board.
A detector on the PA board measures continuously the output level. The
signal from this detector is used by the automatic gain control, AGC, to
supervise and, if necessary, reduce the output power to keep it under a
maximum level. The AGC gain control affects several of the amplification
stages.
BA in high power CDMA
repeaters only.
In high power CDMA repeaters, a booster amplifier (BA) boosts the
output downlink signal by typically 6dB. The BA amplifier is powered by
a high power PSU2. Note that the booster amplifier (BA) is only present
in the downlink path, and only in high power CDMA repeaters.
The output signal passes a duplex filter (DPX) and a directional coupler
(DC) before it is fed to the repeater MS antenna.
ALLGON System AB AR Repeaters Functional Description
User’s Manual VD203 66/EN Rev. P1A 2000-09 5 - 13