What does the air raid siren mean?

The long blast of air defense sirens is generally used for disaster forecasting and emergency notification in disaster relief and emergencies. It is used for civil air defense in wartime. It is used by people's governments at all levels to implement civil air defense command and organize the evacuation of personnel. The basic method is to sound an air defense siren to remind people when the city is threatened by air raids.

Alarms are divided into three types: electric alarms, electric alarms, and hand alarms. The electric siren uses a motor as the main component of the siren, converting electrical energy into sound; the electroacoustic siren is composed of a host amplifier and a speaker; the hand-cranked siren is a supplementary warning device for the electric siren and the electroacoustic siren.

Alarm types

1. Pre-alarm: sound for 36 seconds, stop for 24 seconds, repeat 3 times as a cycle, time 3 minutes. Citizens should immediately stop all work, turn off the power supply at home, turn off the gas, extinguish the fire, close the doors and windows, carry valid documents, daily necessities and protective equipment, and quickly evacuate to nearby underground air raid shelters, civil air defense projects, and air raid shelters.

2. Air raid siren: sound for 6 seconds, stop for 6 seconds, and repeat 15 times as a cycle, lasting 3 minutes. Unable to enter underground air raid shelters, civil air defense projects and air raid shelters, citizens took advantage of the terrain and features to hide nearby and lay on the ground with their heads in their hands.

3. Clear the alarm: After a long continuous sound for 3 minutes, citizens can exit the underground air raid shelters, civil air defense projects and air raid shelters and resume normal work.