User Manual

Axell Wireless Limited
Technical Literature
Fiber Optic, Uplink, Band Selective,
800MHz Booster Amplifier
Document Number
60
-
275001HBK
Issue No. 2
Date 13/06/2011
Page
6
of
16
3. Equipment Overview
Fiber Optic, Uplink, Band Selective, 800MHz, Booster Amplifier Part Number 60-275001 is built into
an 8U, 19” rack mount shelf. The amplifier is used to filter and amplify the signal levels of one
800MHz band, 812.0MHz to 816.0MHz; in the Uplink direction only.
The Uplink Optical signal is received from Fiber Optic Transmitter Part Number 60-275101 via Fiber
Optic cable at the FC/APC port labelled “F/O” (annotated “A” in 3.4.); the optical Uplink signal then
enters Fiber Optic RX Module 20-005501 which demodulates the Optical signal to RF.
The RF signal then passes through a Bandpass Filter 02-011601 tuned to pass the Uplink band and
to reject out-of-band noise; after leaving the Bandpass filter the Uplink signal passes through the
Variable Switched Attenuator 10-000701 which can introduce up to 30dB of signal attenuation if
required. The attenuator is controlled by a set of four toggle switches (annotated “E” in section 3.5.)
on the front panel of the Amplifier shelf; each switch is clearly marked with the attenuation it provides,
and the total attenuation in-line is the sum of the values switched in.
After leaving the switched attenuator the Uplink signal passes first through the AGC Attenuator
Module 17-016401 (which is controlled by AGC Detector Module 17-019801 fitted further on in the RF
path) and then through a 1W Low Power Amplifier 12-030302 which provides 30dB of gain.
The Low Noise Amplifier is followed by a 20W Power Amplifier 12-023301 which provides 36dB of
gain and then the Uplink signal passes through the AGC Detector Module 17-019801 which regulates
the gain level by adjusting AGC Attenuator Module 17-016401.
The AGC Detector Module monitors the RF level being delivered by the power amplifier, and when a
certain threshold is reached it begins to increase the value of the AGC Attenuator Module to limit the
RF output to the (factory set) threshold. Therefore overloading of the power amplifier is avoided.
After passing through the AGC Detector Module the Uplink path passes through a second Bandpass
Filter 02-011601 to further reject out-of-band noise and then through VSWR Monitor 21-003207.
Upon leaving the VSWR Monitor the Uplink signal exits the Amplifier shelf for the Uplink Antenna
System via the N type port labelled “RF Base” (annotated “F” in section 3.5.).
The Amplifier is powered from mains AC at 110V which drives an internal 400W PSU module
providing 24V DC for the power amplifier; a DC/DC converter provides 12V DC for the remaining
active modules.
The Amplifier has an alarm system; both of the amplifier modules, the PSU, DC/DC converter, the
F/O RX and the VSWR Monitor modules carry their own voltage-free, dry contact alarm relay outputs
which are summed at the 15 way “D” alarm output connector on the rear of the case (annotated “L” in
section 3.5.).