System overview
EST3 Installation and Service Manual 1.9
Network Audio Riser
Network Data Riser
Equipment Enclosure
Local Rail Bus
Central
Processor
Module
Backup
Amplifier
Zoned
Amplifier
Zoned
Amplifier
Zoned
Amplifier
Zoned
Amplifier
AlertEVACPagePage
Figure 1-5: Single amplifier failure
The amplifier failure caused the backup amplifier to
automatically connect to the same audio source as the failed
amplifier. The output of the backup amplifier replaced the output
of the failed amplifier.
Note: The backup amplifier will not replace an amplifier that has
detected a field wiring problem to prevent the amplifier from
driving into a shorted circuit.
3-ASU Audio Source Unit
The 3-ASU is the source of the network audio riser. Available
audio sources are local and remote voice PAGE functions and
the firefighter telephone PAGE function. An integral tone
generator database is provided for the EVAC, ALERT and other
functions. Alternately, the 3-ASU’s integral digital voice
message playback unit can simultaneously provide up to 8
different prerecorded audio messages that may be assigned to
any channel.
The multiplexer within the 3-ASU converts and compresses the
real-time audio signal and converts it to a digital format. The
output of the digital message playback unit and the integral tone
generator database is already in the digital format. The 8 signal
sources in digital format are then combined together as selected
by the system designer using a multiplexer. This makes up the
network audio riser signal.
Note: The backup amplifier
will back up a failed
amplifier if it was being
used for Page, EVAC, or
Alert. It will not back up an
amplifier being used on an
Auxiliary or General
channel.
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