User Manual

P B L Tunnels Loc 2 Units 1 & 2 + 800MHz BDA
Maintenance Handbook
H/book Number:-60-056100HBKM
Issue No:-1
Date:-13/02/2003
Page:-11 of 11
2. OVERVIEW/SYSTEM DESCRIPTION
The AFL Fibre feed Amplifiers for the Pasadena Blue line project are 2 way on-band RF
amplifiers. Their application is as an interface between the fibre optical link from the off air
amplifiers and the tunnel antenna/leaky feeder system. There are two units one designated
‘UNIT 1’ for the frequencies in the 470-473MHz range , the other ‘UNIT 2’ for the
frequencies in the 483-486MHz range.
Each unit is housed in an environmentally protected IP65 steel wall-mount case. Handles are
provided for carrying the unit and the door is fitted with locks. The unit interfaces with ‘N’
type female connectors for RF connections and heavy duty connectors for routing of AC
power supply input and alarm output wiring. Cable glands are provided for routing of the
Fibre optic cable in to the unit.
To provide adequate selectivity in the Downlink and Uplink paths, combline design duplexers
are used at the input and output ports. To provide the required gain to reach the required
signal levels, low-noise amplifiers (LNA’s) are used in each path, these being followed by
power amplifier modules in the uplink to provide the required intermodulation performance.
Gain adjustment is available locally using switched attenuators.
Note that “Downlink” refers to the RF path from FO receiver to the leaky feeder port and that
“Uplink” refers to the RF path from the leaky feeder port to the FO transmitter.
The AFL 800MHz Off Air Amplifier for the Pasadena Blue line project is a 2 way on-band RF
amplifier. It’s application is as an air interface between the donor radio site and the tunnel
leaky feeder system. Each unit is housed in an environmentally protected IP65 steel wall-
mount case. Handles are provided for carrying the unit and the door is fitted with locks. The
unit interfaces with ‘N’ type female connectors for RF connections and heavy duty connectors
for routing of AC power supply input and alarm output wiring.