Gilderfluke&Co old MACs 8 bit Digital Audio System - Manual (Page 89)

zone will be accessed the next time the the microphoneÕs push-to-talk button is pressed. When operating
in this latter mode, you can tell the stationÕs microphone button to revert to the PA zone it normally
accesses when it is released.
The Phantom PA STATIONS are used for automated announcements and automated 'emergency'
spiels. In this application, instead of having a microphone attached to it, the Phantom PA STATION uses
the output of one of the Digital Audio Repeater / Mixer cards as its input. This card is usually configured
in the 'loop while' mode so that it will loop as long as the start input is active. The enabling input for the
Phantom PA STATION comes from the 'running status' output of this Digital Audio Repeater / Mixer card.
When the Repeater with the automated spiel on it is started by a switch closure on its start input, it
automatically selects the required PA ZONE through the PHANTOM PA STATION. The spiel will continue
until the enabling signal is released and the spiel has finished. In emergency spiel applications, you may
want to assign the phantom PA STATION a fairly low priority so that a live person giving useful information
can easily 'step' on the canned spiel. If the audio system is being controlled by a serial data link from
another computer or control system, serial commands can be used to select and start canned spiels
and route them to the desired PA ZONES.
The wiring needed by any PA STATION is a single eight conductor modular style telephone cable. This
will normally provide all the power, communications, and audio signals to the PA STATION. On some
longer runs (greater than 1000 feet, it may be necessary to add a local power supply to the PA STATION.
If absolute silence is required on the PA audio channel, then a shielded twisted pair is recommended for
the microphone line.
All wires between the PA STATIONS and the MA-100 or MA-200 panels are transformer or opto-
isolated. MOV varistors can be used between each of the wires and chassis (earth) ground to provide
lightning protection if needed.
G ILDERFLUKE & C o . ¥ 205 S OUTH F LOWER S T . ¥ B URBANK , C ALIF . 91502-2102 ¥ 818/840-9484 ¥ FAX 818/840-9485
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