User's Guide

Maintenance Handbook (1)
Baltimore Radio Repeater System
Handbook No. 60-166101HBKM Page 24 of 33
4.4 Rack Mounted Equipment
The size and weight of the equipment racks mean that they represent a significant topple hazard
unless they are bolted to the floor though the mounting holes in the base of the unit. In the interests of
safety this should be done before any electrical, RF, or optical connections are made.
The equipment must be located on a flat, level surface that is made from a material suitable for
bearing the weight of the rack assemblies. If the installer is in any doubt about the suitability of a site it
is recommended that he consult with an appropriately qualified Structural Engineer.
It is important in determining the location of the rack within the room that space is allowed for access
to the front and rear of the equipment. To enable maintenance to be carried out, the front doors of
each rack must be able to open fully. In this AFL system, all RF, optical and power interfaces are
located on the rear panels of the shelves; the cable interfaces to external equipment, mains, LCX
feeds, fibre cables etc., is from the floor area.
It is recommended that the mains supply connection is made by a qualified electrician, who must
satisfy himself that the supply will be the correct voltage and of sufficient capacity.
All electrical, optical and RF connections should be completed and double checked prior to power
being applied for the first time.
4.5 Optical Connections
The optical input and output ports will be located on the appropriate E/O shelf as shown in the
rack layout drawing and the system layout drawing. The ports are supplied with a green plastic
cover, which must be removed prior to the connection of the fibre cable. Ensure that transmitter
and receiver fibre cable are identified to prevent misconnection. At the master site, the fibre
transmitters are in the downlink path with the receivers in the uplink. At remote sites the fibre
transmitters are in the uplink with the receivers in the downlink. Observe optical safety
precautions in section 1. when handling fibre optic components.
The individual fibre optic 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 RX 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.
Ensure that connections are kept clean and are fully tightened.