Typically, alarm sounders for wide area signalling, such as horn loudspeakers or PA loudspeakers consist of three individual sounders that are pole-mounted at 120° to give full 360° coverage; in order to minimise cabling costs, the systems are often battery powered and are radio controlled.
As well as providing wide area coverage, such alarm sounder systems are often used on building and construction sites, where they provide excellent protection levels for the workforce. Typically, the horn loudspeakers are initiated from radio manual call points, either through a system of master/slave control panels or directly if the system is self contained.
