User Manual

Users Guide - Andrew InCell™ Fiber Optic Distributed Antenna System
2-2
CDU Description
The Central Distribution Unit (CDU) is the central hub of the InCell Fiber Optic Distributed
Antenna System. The CDU is housed in a standard 1U tall, 19” rack mount chassis for mounting
in equipment racks or telecom racks. The CDU interfaces to the external wireless infrastructure
through either an in-building base station or through an off-air interface that sends and receives
signals to an outdoor base station that is located nearby the building.
The CDU simultaneously passes the RF downlink signal from the base station to the indoor
mobile phone and the passes RF uplink signal from the indoor mobile phones to the base station.
The CDU splits the downlink RF signals for distribution to six Enhanced Remote Antenna Units
(ERAUs) via fiber optic interfaces. The CDU also receives and combines the uplink signals
from the six ERAUs for distribution to the base station.
For system fault detection, the CDU generates and distributes an RF pilot tone that is used to
continuously monitor uplink and downlink signal paths between the CDU and each of the six
ERAUs. Faults with any of the six ERAUs or the any of the six optical downlink cables or six
optical uplink cables cause fault indicators on the CDU to light up and also switches remote
alarm signals on the CDU.
The CDU is delivered with rack mount hardware to support mounting in standard equipment
racks as mentioned above. The CDU may also be mounted to a wall using optional wall mount
brackets.
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Figure 2-1. InCell™ Central Distribution Unit (CDU)
CDU features are listed below:
• CDU functions as the heart of the distributed antenna system (DAS)
• Multiple CDUs may be used together to create large DAS systems
• CDU has a pilot tone oscillator that provides continuous system fault detection
• Provides DC power to six ERAUs up to 1000’ away, CDU uses universal AC power
• Easily installed in standard 19” equipment rack or telecom rack