Ver. 0 8
The signal from the base station is received via the repeater donor (BS) antenna and is
then forwarded through a directional coupler (DC). The signal passes a duplex filter
(DPX), is amplified in a low noise amplifier (LNA), and enters the band selective
amplifier (BSA), which has two parallel bands.
The first mixer stage on the BSA amplifier, which is controlled by a synthesizer,
converts the received frequency down to the IF frequency. The signal is then filtered
by a SAW band pass filter and amplified before it is fed to the second mixer stage,
controlled by the same synthesizer as the previous one, for converting back to the
original frequency. The SAW filter can be adjustable for each BSA has adjustable
bandwidth.
A detector on the PA measures continuously the output level. The signal from this
detector is used by the automatic level control, ALC, to supervise and, if necessary,
reduce the output power to keep it under a setting level.
The output signal passes duplex filter (DPX) and fed to the repeater service (MS)
antenna.
The uplink signal path, i.e. from the mobile station through the repeater to the base
station, is identical to the downlink path the other way round. Only some levels and
component values differ.
