Diafon ( other Greek. Δϊα - through + other Greek. Φωνή - sound) is a powerful electromagnetic emitter for the production of foggy signals on beacons [1] . They can also be used at fire stations and in other situations when a loud sound signal is not required. In the USSR, it was not widely used [1] .
Sound Description
It produces a stronger sound than a low-pitched siren , turning into a piercing, fading sound, ending in grunt.
Under normal conditions, the range at which the sound of the diafon is heard is 7 to 40 miles.