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
6
of
35
60-232301
Primary F/O D/L feed from
Master Site
Secondary F/O U/L feed to
Master Site
RF D/L O/P to and
U/L I/P from DAS
DOWNLINK
UPLINK
Secondary F/O D/L feed from
Master Site
Primary F/O U/L feed to
Master Site
3. Dual Band Fibre Fed BDA 60-232301
Dual Band Fibre Fed BDA 60-232301 is built into a wall-mounted, environmentally protected (IP65)
aluminium alloy case; RF ports and connectors are also IP65 standard making the entire enclosure
and connecting ports weatherproof. Handles are provided for carrying the unit and the door is fitted
with locks. A supply isolator switch is fitted inside the unit and there are Power On and Alarm
indicators on the outside of the door.
The BDA is used to filter and amplify the signal levels of two (UHF and 800MHz) Downlink and Uplink
frequency bands; one RF port connects to a Distributed Antenna System facing the mobile units and
four Optical Ports (primary and secondary D/L and primary and secondary U/L) receive Optical
signals from (Downlink) and transmit optical signals to (Uplink) the Master Site.
Simplified System Sketch
Downlink
Downlink signals are received from the Master Site as Optical signals via Fibre Optic cables which
enter the case of the BDA at the cable gland annotated “A” in section 3.5. There are two Downlink
optical cables, a primary link and a secondary (redundant) link. The primary Downlink optical cable
connects to the BDA at the SC/APC optical port annotated “B” in section 3.6.1.; the optical signal is
demodulated to RF by the F/O Transceiver Module J1361001 annotated “A” in section 3.6.1. and the
resultant RF Downlink signal passes into RF Relay Assembly 20-001507.
The secondary Downlink optical cable connects to the BDA at the SC/APC optical port annotated “C”
in section 3.6.1.; the optical signal is demodulated to RF by the F/O Transceiver Module J1361001
annotated “D” in section 3.6.1. and the resultant RF Downlink signal also passes into RF Relay
Assembly 20-001507 which is normally set to pass the primary signal but if the primary signal strength
falls below a pre-set level then the RF relay switches to the secondary Downlink path. After leaving
the RF relay the Downlink signal passes through an AGC Detector Module 17-019802 which monitors
the strength of the RF signals entering the RF relay and if the primary signal falls below its pre-set
threshold then the AGC Detector switches the RF relay to pass the secondary Downlink signal path.
The Downlink signal then passes through a Crossband Coupler 07-004814 (annotated “G” in sections
3.6.2. & 3.6.3.) which splits the UHF band signal from the 800MHz band signal.
UHF Downlink
The UHF branch then passes through a bandpass filter 02-010501(annotated “H” in section 3.6.2.)
which is tuned to pass the UHF Downlink passband and to reject out-of-band noise and then passes
through Variable Switched Attenuator 10-000901 (annotated “I” in section 3.6.2.) which can provide
up to 15dB 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.