User Manual

Axell Wireless Limited
Technical Literature
Dual Band Fiber Fed BDA 60-232301
Document Number
60
-
232301HBK
Issue No.
2
Date
22
/
12
/
2009
Page
9
of
35
After leaving the AGC Detector Module the UHF Uplink passes through a second Crossband Coupler
07-004814 (annotated “P” in sections 3.6.4. & 3.6.5.) which combines the UHF Uplink with the
800MHz band Uplink path; the combined signal then passes through a 3dB Splitter/Combiner 05-
002901 (annotated “Q” in sections 3.6.4. & 3.6.5.) which splits the combined Uplink signal into two
equal paths.
One path is fed to the F/O Transceiver Module J1361001 (annotated “R” in sections 3.6.4. & 3.6.5.)
for the primary optical link. The F/O Transceiver Module modulates the RF signal onto a laser and the
primary optical uplink exits the BDA for the master site via the SC/APC optical port annotated “T” in
sections 3.6.4. & 3.6.5.
The second branch of the Uplink path is fed to the F/O Transceiver Module J1361001 (annotated “S”
in sections 3.6.4. & 3.6.5.) for the secondary optical link. The F/O Transceiver Module modulates the
RF signal onto a laser and the secondary optical uplink exits the BDA for the master site via the
SC/APC optical port annotated “U” in sections 3.6.4. & 3.6.5.
800MHz Uplink
After passing through Crossband Coupler 07-004814 (annotated “B” in sections 3.6.4. & 3.6.5.) the
800MHz branch then passes through Bandpass filter 02-007201 (annotated “C” in section 3.6.5.)
which is tuned to pass the 800MHz band Uplink passband and to reject out-of-band noise and then
passes through the first of two amplification stages.
The first stage is composed of two Low Noise Amplifiers 11-006702, arranged in parallel (each
providing 30dB of signal gain). The signal is split into two equal paths by a 3dB Splitter/Combiner 05-
002602 (annotated “D” in section 3.6.5.) and each path passes through one of the LNAs (annotated
“E” and “F” in section 3.6.5.) before being recombined by a second 2 way splitter/combiner 05-002602
(annotated “G” in section 3.6.5.).
The 800MHz Uplink then passes through Variable Switched Attenuator 10-000701 (annotated “H” in
section 3.6.5.) which can provide up to 30dB of attenuation in 1dB steps if required, the attenuation is
controlled by a set of four toggle switches on the body of the attenuator; 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 attenuator the 800MHz Uplink passes through AGC Attenuator Module 17-016401
(annotated “I” in section 3.6.5.) which is controlled by UHF Uplink AGC Detector Module 17-019802
and is capable of providing up to 15dB of signal attenuation.
The 800MHz Uplink then passes through a second Bandpass Filter 02-007201 to further reject out-of-
band noise and then through the second stage of amplification, the second stage is composed of two
1W Low Power Amplifiers 12-030302 arranged in parallel (each providing 30dB of signal gain). The
signal is split into two equal paths by a 3dB Splitter/Combiner 05-002602 (annotated “K” in section
3.6.5.) and each path passes through one of the PAs (annotated “L” and “M” in section 3.6.5.) before
being recombined by a second 2 way splitter/combiner 05-002602 (annotated “N” in section 3.6.5.).
After leaving the Low Power Amplifiers the 800MHz Uplink signal path passes through an AGC
Detector Module 17-019802 (annotated “O” in section 3.6.5.) 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 leaving the AGC Detector Module the 800MHz Uplink passes through a second Crossband
Coupler 07-004814 (annotated “P” in sections 3.6.4. & 3.6.5.) which combines the 800MHz Uplink
with the UHF band Uplink path; the combined signal then passes through a 3dB Splitter/Combiner 05-
002901 (annotated “Q” in sections 3.6.4. & 3.6.5.) which splits the combined Uplink signal into two
equal paths.