User Manual

Fibre Optic Master and Remote Site
User Handbook
Document Number: 60-212701HBK - Issue No. 1 Page 8 of 50
3. MASTER SITE 60-212701
The Master Site Shelf is a 3U Rack mount shelf and provides two separate RF paths, uplink and
downlink with provision to vary the gain of either path using a switched variable attenuator, one in
each path. The active Fibre Optic modules in the unit are powered from an internal 12V PSU which
runs from a mains feed of 110V AC
The downlink signal is received from the antenna and enters the master site via the port labelled “TX”,
the signal passes through a switched variable attenuator (10-000801) providing up to 30dB of
attenuation 2dB steps. After leaving the attenuator the signal is split into two equal paths by a 3dB
splitter/combiner (05-002603) and each path is passed into a Fibre Optic Transmitter (20-005401)
where the signal is modulated onto a laser as an optical signal for transmission to the remote site via
fibre optic cable. The fibre optic signal leaves the master site via the ports labelled “F/O DL” (Fibre
Optic Downlink). Only one “F/O DL” port is used, the second one being available for future expansion.
Uplink signals are received at the master site as optical signals sent from the remote site, the fibre
optic cable carrying the optical signals enter the master site via the ports labelled “F/O UL” (Only one
“F/O UL” port is used, the second one being available for future expansion). Upon entering the master
site the optical signal is passed to a fibre optic receiver (20-005501) where the signal is demodulated
into an RF signal. After leaving the fibre optic receivers the two RF signal paths are combined by a
3dB splitter/combiner (05-002603) to produce a single path which then passes through a switched
variable attenuator (10-000701) providing up to 30dB of attenuation 2dB steps. After leaving the
attenuator the RF signal leaves the master site via the port labelled “RX”
3.1. 60-212701 Parts List (Major Components)
Component
Part
Component Part Description Qty Per
Assembly
05-002603 UHF 3dB Splitter/Combiner 2
10-000701 Switched Attenuator 0-30dB 0.25W 1
10-000801 Switched Attenuator 0-30dB 1W 1
20-005401 Fibre Optic Transmitter (2.7GHz) 1
20-005501 Fibre Optic Receiver (2.7GHz) 1
80-008901 12V Relay Assembly 1
96-300048 PSU 50W (12V 5A) 1
96-920022 Circuit Breaker (3A) 1
The individual fibre optic TX and RX units are fitted with a pair of status indicators on their front
panels. One is a green LED, which indicates that the unit is connected to a 12 Volt DC power supply.
This indicator is common to both transmit and receive units. The second LED on the TX module
indicates that the laser is operating (transmitting). On the RX unit the second LED indicates that a
laser-light signal is being received.
When all the fibre connections are completed and power to each site is connected each fibre unit
must show two illuminated indicators.