User Manual

PBL UHF 1 & 2 Air Interface
Maintenance Handbook
H/book Number:-60-055900HBKM
Issue No:-1
Date:-13/02/2003
Page:-11 of 11
2. OVERVIEW/SYSTEM DESCRIPTION
The AFL Off air Amplifiers for the Pasadena Blue line project are 2 way on-band RF
amplifiers. Their application is as an interface between the donor radio sites and the Fibre optic
receivers and transmitters which will extend coverage to the locations via the fibre optic link.
There are two units one designated for the ‘UHF1’ frequencies the other for the ‘UHF2’
frequencies.
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 bandpass
quadplexers and duplexers are used at the air interface ports. In addition each channel to be
passed is selected by a 15kHz or 25KHz Channel module which provides a high level of
rejection at adjacent channels. 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 the base station (donor site) to the FO
transmitter and that “Uplink” refers to the RF path from the FO receiver to the remote base
station.