A civil defense siren is a siren used to provide an emergency population warning to the general population of approaching danger. Initially designed to warn city dwellers of air raids during World War II, they were later used to warn of nuclear attack and natural disasters, such as tornadoes. The generalized nature of sirens led to many of them being replaced with more specific warnings, such as the broadcast-based Emergency Alert System and the Cell Broadcast-based Wireless Emergency Alerts and EU-Alert mobile technologies.
An alarm device is a mechanism that gives an audible, visual, combination, or other kind of alarm signal to alert someone to a problem or condition that requires urgent attention.
A long-range acoustic device (LRAD), acoustic hailing device (AHD) or sound cannon is a specialized loudspeaker that produces sound at high power for communicating at a distance. It has been used as a method of crowd control, which has caused permanent hearing damage, having an extremely high decibel capacity. Other uses have included for negotiations in siege situations; to deal with piracy at sea; for mass notification during natural disasters or other emergencies; and by defense forces, including several navies.
A siren is a loud noise-making device. There are two general types: mechanical and electronic. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines.
Automatic Warning System (AWS) is a railway safety system invented and predominantly used in the United Kingdom. It provides a train driver with an audible indication of whether the next signal they are approaching is clear or at caution. Depending on the upcoming signal state, the AWS will either produce a 'horn' sound, or a 'bell' sound. If the train driver fails to acknowledge a warning indication, an emergency brake application is initiated by the AWS; if the driver correctly acknowledges the warning indication, by pressing an acknowledgement button, then a visual 'sunflower' is displayed to the driver, as a reminder of the warning.
An emergency population warning, or public warning system is a method where by local, regional, or national authorities can contact or notify members of the public to warn them of an impending emergency. These warnings may be necessary for a number of reasons, including:
An air horn is a pneumatic device designed to create an extremely loud noise for signaling purposes. It usually consists of a source which produces compressed air, which passes into a horn through a reed or diaphragm. The stream of air causes the reed or diaphragm to vibrate, creating sound waves, then the horn amplifies the sound making it louder. Air horns are widely employed as vehicle horns, installed on large buses, semi-trailer trucks, fire trucks, trains, and some ambulances as a warning device, and on ships as a signaling device.
The Singapore Civil Defence Force (SCDF) is a uniformed organisation in Singapore under the Ministry of Home Affairs that provides emergency services such as firefighting, technical rescue, and emergency medical services, and coordinates national civil defence programme.
Total Defence is Singapore's whole-of-society national defence concept, based on the premise that every aspect of society contributes to the collective defence of the state.
The United Kingdom Warning and Monitoring Organisation (UKWMO) was a British civilian organisation operating to provide UK military and civilian authorities with data on nuclear explosions and forecasts of fallout across the country in the event of nuclear war.
The Disaster Assistance and Rescue Team (DART) is the elite unit of the Singapore Civil Defence Force (SCDF) that specialises in complex incidents such as technical rescue, urban search and rescue, water rescue operations and prolonged firefighting.
A train horn is an air horn used as an audible warning device on diesel and electric-powered trains. Its primary purpose is to alert persons and animals to an oncoming train, especially when approaching a level crossing. They are often extremely loud, allowing them to be heard from great distances. They are also used for acknowledging signals given by railroad employees, such as during switching operations. For steam locomotives, the equivalent device is a train whistle.
The Standard Emergency Warning Signal (SEWS) is a warning siren used in Australia to alert the public of danger. The siren is played over radio, television or public address systems in public places to warn of bushfire, flood, cyclone, tsunami, earthquake or terrorist attack.
Federal Signal Modulators are electronic warning devices produced by Federal Signal Corporation that are used to alert the public about tornadoes, severe weather, earthquakes, fires, lahars, tsunamis, or any other disaster. They are identified mostly by their distinctive stacked "flying saucer" design. The Modulator II is sold based on the more compact chassis of the siren compared to the original Modulators.
SiraTone was a brand of electronic outdoor warning sirens produced by Federal Signal Corporation which began production in the early 1980s. These sirens were designed to broadcast high-intensity warning signals over a large area. SiraTone products are/were used for natural disaster notification, HAZMAT incident notification, fire call systems, and more. The SiraTone product line is no longer in production. The product line was succeeded by the Modulator and DSA electronic outdoor warning sirens.
American Signal Corporation (ASC) is an outdoor warning siren and mass notification company in the United States. ASC was founded in 1873 as Biersach and Niedermeyer (B&N). After performing poorly, the company reformed as Alerting Communicators of America (ACA) in 1968, and expanded the line of warning systems they produced. In 1992, ACA went bankrupt and was bought and reformed as the American Signal Corporation.
The ACA Hurricane is an electro-mechanical and rotating-directional, 130dB civil defense siren, created and produced by Alerting Communicators of America (ACA). ACA began manufacturing the Hurricane 130 in 1968, and ended production in 1981. The Hurricane 130 is very similar to the Federal Signal Thunderbolt series, being a supercharged siren.
In civil defense sirens, the ATI High-Power Speaker Station (HPSS) is an electronic outdoor warning siren manufactured by Acoustic Technology, Inc (ATI) that is used to alert citizens of air raids, and natural disasters.
Canadian Line Materials LTD. (CLM) was a Canadian siren manufacturing company which built civil defense sirens. These sirens were built and installed all over Canada to warn residents and military about incoming nuclear attacks from the USSR during the Cold War.
The Thunderbolt is a mechanical outdoor warning siren that was manufactured by Federal Signal Corporation from 1951 until its production ended in 1991. It is a unidirectional, rotating siren with a large square-shaped horn, and can come in various colors, usually yellow, by request.
