User Manual

Axell Wireless Limited
Technical Literature
L.A. M.T.A. Remote Sites
Document Number 80-301401HBKM Issue No. 1 Date 13/06/2008 Page 125 of 148
4.13. 800MHz Amplifier Shelf 80-301411
800MHz Amplifier Shelf 80-301411 provides the amplification stages for the 800 MHz paths, The unit
is housed in an 8U, 19” rack mount shelf which is mounted in Rack 2
The Downlink 800MHz signal is received at the port labelled “DOWNLINK INPUT” (Annotated A in the
picture in section 4.13.4.2.). The Downlink 800MHz path passes through a bandpass filter to remove
out of band noise and then a switched attenuator providing 0 to 30 dB of RF signal attenuation, after
the Attenuator the signal passes through the first of two amplification stages. This first stage is
provided by a low noise amplifier which gives approximately 19dB of gain.
After the Low Noise Amplifier the Downlink 800MHz signal passes through the second amplification
stage; the signal is first split into two equal paths and then each path is passed through a 20W power
amplifier and then the two signal paths are re-combined. The second stage amplifiers are straddled
by an Automatic Gain Control assembly providing limiting to the output signals in the case of high
input signals.
After leaving the second stage amplifiers the Downlink 800MHz signal path passes through a second
bandpass filter and exits the Shelf via the port labelled “DOWNLINK OUTPUT” ( B in section
4.13.4.2.).
The Uplink 800MHz Signal is received at the port labelled “UPLINK INPUT” (C in section 4.13.4.2.).
The Uplink 800MHz path passes through a bandpass filter to remove out of band noise and then into
the first of two amplification stages, the first stage is provided by a low noise amplifier which gives
approximately 19dB of gain; after leaving the Low Noise Amplifier the signal passes through a
switched attenuator providing 0 to 30 dB of RF signal attenuation,
After leaving the switched attenuator the Uplink 800MHz path passes through the second stage of
amplification which is provided by a 5W power amplifier giving approx. 30dB of gain; this second
amplification stage is straddled by an Automatic Gain Control assembly providing limiting to the output
signals in the case of high input signals.
After leaving the second amplification stage the Uplink 800MHz path passes through a second
bandpass filter and exits the Shelf via the port labelled “UPLINK OUTPUT” (D in section 4.13.4.2.).
800MHz Amplifier Shelf 80-301411 is provided with a 24V DC input to power the amplifier modules
within and those amplifier modules are configured to provide alarm status reports.