The "strongest" voice in the city's presence: It turns out that the air defense alarm is not a loudspeaker...

June 13, 2022

Origin: It's actually a musical instrument...
Air Defense Speaker

Strange to say, the siren used as an anti-aircraft alarm appeared earlier than any kind of anti-aircraft weapon! Even 100 years after he appeared, the plane really appeared... The earliest siren was actually invented as a musical instrument...
In the 18th century, Finnish physicist John Robinson invented a simple musical instrument, which was driven by a rotating ringing wheel and adjusted to different melodies using the openings on the opening and closing wheels.
It was later discovered that this design could easily make a loud, screeching sound, and some people used it as a siren. The lighthouse was first installed on the Isle of Creed in Scotland in 1887 as an early warning against disasters. This is the first time this type of device has been used as a siren.
With the development and popularization of the commercial power industry, sirens driven by electric motors began to spread rapidly. The electric motor can greatly enhance its sound potential, and at the same time, the electric amplifier can give full play to its performance…

In addition to fire trucks, since the 20th century, sirens have been widely used for early warning of large-scale disasters such as disaster forecasting and air defense evacuation. When people heard this strange sound, they would spontaneously gather at the predetermined location for evacuation. So, air defense siren is still called Civil defense siren in English now (civil defense siren/civil defense siren).

Air Raid Loudspeaker

The alarm goes off: it makes sense after all

At present, cities in most countries in the world have built relatively complete civil defense alarm systems. The United Kingdom and Germany in World War II "loved each other and exploded"; the United States and the Soviet Union in the Cold War were waiting for their nuclear weapons; China and Taiwan were one country with two alarms; there are indeed many interesting alarms in history...

Let's talk about the United Kingdom first. As one of the countries with the longest air raids in World War II, the United Kingdom has summed up a wealth of civil defense experience. In every town in the UK, there are two complete alarm and sound reinforcement systems. Once the air strike warning system is received, it will take effect immediately.

The scary thing about the British is that they are universal! Each of their villages also has hand-cranked civil defence sirens. That is to say, no matter where in the UK an air strike is launched, the siren can always be heard for the first time!

Britain lost only about 700,000 people in World War II, the least among the major warring countries, which may be related to its perfect civil defense system!

The United States is another good example: in the early 20th century, the alarm system in the United States was basically realized by hand-operated bells…

Before World War II, the civil air defense alarm system was initially popularized. During the Cold War, it grew rapidly, forming the most rigorous alarm system in the world! Not only was it the first to use more advanced electronic sirens. And there is a strict set of rules. It is mainly divided into two categories: rapid attack signals, and smooth warning signals.

Attack Warning: Continuously play a rapid attack signal for 3 to 5 minutes. Usually this signal is played when an enemy air strike or missile, including a nuclear strike, is detected. At the same time as the alarm was carried out, all civil defense personnel were dispatched to guide the public to enter the underground shelter in an orderly manner.

Attention Alarm: Play a steady attention signal for 3~5 minutes continuously. Generally used for general emergencies. It is mostly used for natural disasters such as tornadoes. Its significance is to remind citizens in the city to turn on the radio and TV to watch related emergency reports as soon as possible. And implement specific measures according to the corresponding instructions in the program.

China's alarm system is also quite sound, but with the slowdown in the world after the Cold War, many people do not know the specific meaning of air defense alarms...

China's civil air defense warning facilities are located in various cities, and are designed to use air defense warnings to inform the public of possible dangers when the country is invaded and the country enters a state of emergency. Civil air defense workers will guide the masses to the designated air defense fortifications for refuge.

Most of the sirens are manufactured and controlled by the PLA, while the civil air defense department is responsible for their daily maintenance and upkeep. The main alert is divided into three stages:
Warning Warning: Indicates the possibility of an air strike. Includes a 36-second high pitch followed by 24 seconds of silence. One cycle for one minute, 3 cycles as a stage.
Upon hearing this alarm, 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 the nearby underground air defense shelter, Civil air defense engineering, air-raid shelter.
Attack Warning: Indicates that an attack is imminent or in progress. 6 seconds of high tone, 6 seconds of silence. 15 cycles (three minutes) as a phase.
Citizens who cannot enter underground air defense shelters, civil air defense projects, and air raid shelters, please use the terrain and features to hide nearby, lie on the ground and hold your head with both hands.
Post-Assault Warning: Indicates that an attack is over or has come to an end. 3 minutes of sustained treble as a separate stage. Citizens can get out of underground air defense shelters, civil air defense projects, and air raid shelters and resume normal work.

Taiwan's alert system is relatively simple. There are two types: emergency alerts and clear alerts.

Emergency alarm: 1 long, 2 short, long sound for 15 seconds, short sound for 5 seconds, pause for 5 seconds between long and short sounds, 3 consecutive times, a total of 115 seconds.
To cancel the alarm: 1 long tone for a total of 90 seconds.
Unlike China, which always sounds the alarm on anniversaries or specific dates: every year, Taiwan will randomly conduct a trial release on a certain day, and it will be played for 30 minutes each time.

Maybe one day, the air defense siren suddenly sounded beside you. It is very necessary to be able to respond immediately and know what to do!
After all, in turbulent times of war: the preservation of lives means a lot to the individual civilian. For the country, the preservation of life is also the greatest contribution to the country!
Air Raid Alarm Speaker