EST3 digitized audio can deliver up to eight audio messages simultaneously over a single pair of wires!

All audio messages and live pages originate at the Audio Source Unit (ASU) that can store up to 32 minutes pre-recorded audio messages as computer "WAV" files. These messages can be automatically directed to various areas in a facility under program control. On the receiving end, zoned amplifiers installed in remote fire alarm cabinets receive and decode the digital messages. The messages are then amplified and sent out to the speakers.

The availability of eight different channels opens a number of new simultaneous notification possibilities:

1. Live voice page;
   
2. Fire floor evacuation message;
   
3. Alert message on floors above and below the fire;
   
4. Stairwell evacuation reinforcement message;
   
5. Elevator cab information messages;
   
6. Lobby message instructing occupants to exit the building;
   
7. Concourse instructions to occupants not to enter the lobby;
   
8. Other instructions to areas not directly affected by fire.

Any combination of the eight audio channels can be automatically directed to any or all areas of the building, with total manual override as required. Eight channel capability assures that one message is never interrupted in order to process another, a common fault with two-channel systems. This eliminates any chance of confusing the occupants with conflicting messages. Security notification messages can easily be integrated into the audio system, and act as a great deterrent as well as reducing the risk of false alarms.

Survivability is also an integral part of EST3’s digitized audio system. Default audio messages are continuously transmitted to all network amplifiers by the ASU. These messages provide audio supervision for the digital audio chain, and act as a default signal if the network data circuit fails or should message control information fail to reach the ASU. If the audio data circuit fails, each amplifier generates a 1KHz temporal (3-3-3) tone that is transmitted during an alarm. In the event of an amplifier failure, a backup audio amplifier is automatically substituted for the failed amplifier in the cabinet, restoring audio capability.