Biamp AudiaEXPI/O-2 - Manual (Page 7)

7
APPLICATIONS
Airport with Central and Local Announcements, plus Background Music
This application demonstrates the use of Audia® in a moderately large airport with a central control room and six concourses,
each with eight boarding gates.
This is a networked system using two Networked Paging Station-1 units, one AudiaEXPI-4 Input Expander unit, one
AudiaEXPI/O-2 Input/Output Expander unit in the central control room with an AudiaFLEX unit, two AudiaEXPI-4 Input
Expander units, an MCA8050 Multi-Channel Amplifier, and eight Networked Paging Station-1 units in each concourse. Signals
from the central control room are distributed to all concourses via fiber-optic transmission of CobraNet® and Ethernet.
The central control room has two Networked Paging Station-1 units for all-call paging, three digital message repeaters for
announcements, a single background music source, one AudiaEXPI-4 Input Expander unit, and one Audia EXPI/O-2
Input/Output Expander unit. Outputs are provided in the central control room for distributed speaker systems (ticket counters,
baggage claim, etc.).
Each of the airport’s six concourses includes eight boarding gates. An AudiaFLEX unit with an MCA 8050 amplifier unit in
each concourse powers the individual boarding gate speaker systems, utilizing two EXPI-4 Input Expander units for analog
inputs and eight Networked Paging Station-1 units for local pages. Each boarding gate has its own local announcement
microphone, ambient sensing microphone and distributed speaker system.
Signals from the central control room are distributed to all concourses as digital audio via CobraNet. To span the physical
distances between units, fiber-optic transmission of CobraNet and Ethernet is employed. In the system design, all
microphones are brought in through Levelers (to provide more consistent paging volumes) and all outputs include equalization
(to enhance intelligibility). Central paging is mixed for distribution to all areas via a Matrix Mixer (2x1). Signals from the three
digital message repeaters are mixed via a Matrix Mixer (3x1), which then feeds a ducker. Background music is fed to this
same ducker, thereby allowing distribution of a “message-over-music” signal to all areas. The message-over-music and
central paging signals are then fed to another ducker, which allows paging to override the message-over-music signals.
Output of this ducker is in turn fed with equalization to the two distributed speaker systems in the central control room.
In each concourse, eight announcement microphones are brought in through individual duckers. The message-over-music
signal from the central control room is distributed to all of these duckers. This allows the message-over-music signal to appear
at all boarding gates, but to be overridden at each boarding gate by announcements from the local push-to-talk microphone.
The outputs of these duckers then feed an additional set of duckers, all of which receive a central paging signal as their other
input. This establishes the following priority-override scheme for each boarding gate: central paging (priority 1); local
announcement (priority 2); digital message repeaters (priority 3); background music (priority 4). Due to periodic arrival and
departure of passengers, background noise levels at each boarding gate fluctuate significantly. Paging and announcements
must continue to be audible, regardless of changes in ambient noise. Therefore, each boarding gate output utilizes an
Ambient Noise Compensator, which provides input for an associated ambient sensing microphone. This allows the volume
level at each boarding gate to be automatically adjusted in compensation for changes in the local ambient noise.