Just like electronic sirens, electronic public address systems are also devices designed for exterior and interior sound distribution. Unlike electronic sirens these systems have the output of the electronic amplifiers divided between several loudspeakers with lower output. The loudspeakers are therefore mounted closer to each other and are commonly connected to the amplifier via 100V distribution systems. The application of smaller outputs and a higher number of loudspeakers make it possible to improve notification clarity and coverage. On the other hand the costs of system establishment and maintenance increase substantially if the system is to cover larger areas. Mainly the lines are susceptible to failures, if they are not placed underground in a proper manner. Underground lines, however, would increase system establishment costs to an even greater extent.

Wireless public address systems
The issues of unreliability and damage susceptibility, in particular in connection with aerial lines, are eliminated via the application of modern wireless public address systems. Wireless public address systems use radio communication for broadcasting both control signals and notifications. They basically consist of a radio broadcasting unit and radio speakers. The acoustic speakers are arranged within the designated area in the same manner as the loudspeakers of line broadcasters.

However, apart from loudspeakers, the acoustic speakers also contain an electronic amplifier and a radio receiver/transmitter. Simpler systems use a radio receiver only. Such acoustic speakers, however, are neither capable of sending status feedback, nor capable of examining the radio channel and thus cannot be used as a warning device, even in the simplest applications. Wireless public address systems do not require direct line connection to the central unit since they receive notifications and control commands via radio. They do, however, require a connection to the electric power network. Wireless public address systems are usually mounted on public lighting poles and at night, when lighting is on, their built-in batteries are being recharged to be used as a power supply system during the day. In some countries free radio channels are assigned to such systems making the establishment of these systems easier. These channels can be used if such wireless public address system is used only for informational purposes. Their use as a warning system, however, does not meet safety standards.

Requirements placed on modern public address systems
Current modern public address systems, including our company’s product AMADEO, are capable of combining the requirements placed on electronic sirens and the requirements placed on fire warning systems or industrial warning systems. They also integrate the functions of control and monitoring systems and are even capable of meeting some functions connected with building and operation automation such as gate control, traffic barrier control, ventilation systems etc. thereby representing complex solutions available at optimal prices and meeting the most demanding requirements.

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