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Civil defense siren
A civil defense siren is a form of siren used to warn civilians of approaching danger - a form of emergency population warning. Initially designed to warn city dwellers of air raids (air-raid sirens) during World War II, they were later used to warn of nuclear attack and natural disasters, such as tornadoes (tornado sirens). 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.
By use of varying tones or binary patterns of sound, different alert conditions can be called. Electronic sirens can transmit voice announcements in addition to alert tone signals. Siren systems may be electronically controlled and integrated into other warning systems.
Sirens are sometimes integrated into a warning system that links sirens with other warning media, such as the radio and TV Emergency Alert System, NOAA Weather Radio, telephone alerting systems, Reverse 911, Cable Override, and wireless alerting systems in the United States and the National Public Alerting System, Alert Ready, in Canada. This fluid approach enhances the credibility of warnings and reduces the risk of assumed false alarms by corroborating warning messages through multiple forms of media. The Common Alerting Protocol is a technical standard for this sort of multi-system integration.
Siren installations have many ways of being activated. Commonly used methods are dual-tone multi-frequency signaling (DTMF) or public switched telephone network (PSTN) using telephone lines, but activation can also be done via radio broadcast. This method opens up vulnerability for exploitation, but there are protections from false alarms. These sirens can also be tied into other networks such as a fire department's volunteer notification/paging system. The basics of this type of installation would consist of a device (possibly the same pager the firefighters have) connected to the controller/timer system of the siren. When a page is received, the siren is activated.
A mechanical siren uses a rotor and stator to chop an air stream, which is forced through the siren by radial vanes in the spinning rotor. An example of this type of siren is the Federal Signal 2T22, which was originally developed during the Cold War and produced from the early 1950s to the late 1980s. This particular design employs dual rotors and stators to sound each pitch. Because the sound power output of this type of siren is the same in every direction at all times, it is described as omnidirectional. The Federal Signal 2T22 was also marketed in a three-signal configuration known as the Federal Signal 3T22, with the capability for a high–low signal.
While some mechanical sirens produce sound in all directions simultaneously, other designs produce sound in only one direction, while employing a rotator mechanism to turn the siren head through 360 degrees of rotation. One rare type of mechanical siren, the Federal Signal RSH-10 ("Thunderbeam"), does not rotate or produce equal sound output in all directions. It instead uses a slowly rotating angled disc below the siren which directs the siren's output throughout 360 degrees.
A variation of the electromechanical siren is a supercharged siren. A supercharged siren uses a separate source, usually a supercharger-like blower, which forces air into the rotor assembly of the siren. This increases the air pressure in the rotor assembly, causing the sound output of the siren to increase heavily, which in return increases the sound range by a large amount. The blower is generally driven by an electric motor, but in rare cases it is driven by an engine. Federal Signal took advantage of this design and created their Thunderbolt Siren Series, utilizing Sutorbilt Roots Blowers of different varieties and outputs.
A very early model was the Thunderbolt 2000. The difference between the Thunderbolt 2000 and later editions is that its blower is driven by an Onan two cylinder gas engine. Another example of a siren that has a separate blower is the Alerting Communicators of America (ACA) Hurricane. One more example of a siren with a blower is the SoCal Edison Model 120, utilizing a Centrifugal Style Blower, built specifically for the San Onofre Nuclear Generating Station. The SoCal Edison Model 120 is no longer standing out in public, as only one exists, and is owned privately.
Hub AI
Civil defense siren AI simulator
(@Civil defense siren_simulator)
Civil defense siren
A civil defense siren is a form of siren used to warn civilians of approaching danger - a form of emergency population warning. Initially designed to warn city dwellers of air raids (air-raid sirens) during World War II, they were later used to warn of nuclear attack and natural disasters, such as tornadoes (tornado sirens). 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.
By use of varying tones or binary patterns of sound, different alert conditions can be called. Electronic sirens can transmit voice announcements in addition to alert tone signals. Siren systems may be electronically controlled and integrated into other warning systems.
Sirens are sometimes integrated into a warning system that links sirens with other warning media, such as the radio and TV Emergency Alert System, NOAA Weather Radio, telephone alerting systems, Reverse 911, Cable Override, and wireless alerting systems in the United States and the National Public Alerting System, Alert Ready, in Canada. This fluid approach enhances the credibility of warnings and reduces the risk of assumed false alarms by corroborating warning messages through multiple forms of media. The Common Alerting Protocol is a technical standard for this sort of multi-system integration.
Siren installations have many ways of being activated. Commonly used methods are dual-tone multi-frequency signaling (DTMF) or public switched telephone network (PSTN) using telephone lines, but activation can also be done via radio broadcast. This method opens up vulnerability for exploitation, but there are protections from false alarms. These sirens can also be tied into other networks such as a fire department's volunteer notification/paging system. The basics of this type of installation would consist of a device (possibly the same pager the firefighters have) connected to the controller/timer system of the siren. When a page is received, the siren is activated.
A mechanical siren uses a rotor and stator to chop an air stream, which is forced through the siren by radial vanes in the spinning rotor. An example of this type of siren is the Federal Signal 2T22, which was originally developed during the Cold War and produced from the early 1950s to the late 1980s. This particular design employs dual rotors and stators to sound each pitch. Because the sound power output of this type of siren is the same in every direction at all times, it is described as omnidirectional. The Federal Signal 2T22 was also marketed in a three-signal configuration known as the Federal Signal 3T22, with the capability for a high–low signal.
While some mechanical sirens produce sound in all directions simultaneously, other designs produce sound in only one direction, while employing a rotator mechanism to turn the siren head through 360 degrees of rotation. One rare type of mechanical siren, the Federal Signal RSH-10 ("Thunderbeam"), does not rotate or produce equal sound output in all directions. It instead uses a slowly rotating angled disc below the siren which directs the siren's output throughout 360 degrees.
A variation of the electromechanical siren is a supercharged siren. A supercharged siren uses a separate source, usually a supercharger-like blower, which forces air into the rotor assembly of the siren. This increases the air pressure in the rotor assembly, causing the sound output of the siren to increase heavily, which in return increases the sound range by a large amount. The blower is generally driven by an electric motor, but in rare cases it is driven by an engine. Federal Signal took advantage of this design and created their Thunderbolt Siren Series, utilizing Sutorbilt Roots Blowers of different varieties and outputs.
A very early model was the Thunderbolt 2000. The difference between the Thunderbolt 2000 and later editions is that its blower is driven by an Onan two cylinder gas engine. Another example of a siren that has a separate blower is the Alerting Communicators of America (ACA) Hurricane. One more example of a siren with a blower is the SoCal Edison Model 120, utilizing a Centrifugal Style Blower, built specifically for the San Onofre Nuclear Generating Station. The SoCal Edison Model 120 is no longer standing out in public, as only one exists, and is owned privately.