Federal Signal Modulators (also known as Modulator Speaker Arrays) 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.
The modulator is composed of speaker cells (ranging from two to eight, with the exception of seven) that contain four speaker drivers per cell, although two models (model 6032 and 6048) had additional drivers available when they were still produced. Modulators have an inactive (dummy) speaker cell on the bottom of the stack that is used to help project sound in all directions. Due to the design of active cells, there would be unbalanced sound distribution without the inactive cell. Modulators that are being made now use the UltraVoice controller. When they were first made, they were used with Modulator Control Plus (MPC) and basic/standard Modulator Controls.
Modulator model numbers identify the number of cells, as well as the number of drivers. The first family of modulator arrays consisted of eight different models, as follows: 1004, 2008, 3012, 3024, 4016, 5020, 6024, 6032, and 6048.
In January 2013, Federal Signal released the Modulator II sirens, consisting of the 1004B, 2008B, 3012B, 4016B, 5020B, 6024B, and 8032B models. They provide the same alerting technology as the original modulator, with the exception of a smaller compact chassis and cylindrical modules instead of elliptical ones. [1]
Similar to Federal Signal's previous Electronic Outdoor Warning Siren series, the Modulator can produce seven standard warning tones. The seven standard tones are Wail, Alternate Wail, Pulsed Wail, Steady, Alternate Steady, Pulsed Steady and Westminster Chimes. [2] If properly equipped, the Modulator can also employ voice notification to give specific information or to give a more clear understanding of an emergency situation. They have also been known to play Star Spangled Banner during tests on or near the 4th of July, and also on military bases.
The sirens can be activated by radio using single tone, two-tone, DTMF, MSK or POCSAG over analog, digital and trunking systems, or by satellite, cellular, landline or IP. They are also capable of being activated automatically by the Emergency Alert System. [2]
The Modulator has a similar setup to the Whelen WPS 2700, 2800, 2900, and OmniAlert omnidirectional speaker arrays. The Whelen arrays have single driver cells, [3] while Modulators have multi-driver cells. The American Signal I-Force siren, which uses stacked, elliptical speaker cells that provide omnidirectional sound output, is also similar to the Modulator.
The Modulators in Chicago's siren system formerly used to run on the Alternate Wail tone during tornado warnings in order to vary from emergency vehicle sirens. However, in O'Hare International Airport, instead of using the main UV Wail or Attack, they use an Eclipse 8 (possibly) sound card doing attack. Before that is the Westminster Chimes and voice. The city of Chicago no longer does its Alternate Wail mode, and was replaced by Attack mode in the late 2010s.
The city of Moore, Oklahoma is well known for their Modulators being placed closer together in comparison to other cities. They are placed only a half-mile from each other in some parts of the city. Until 2017, some sirens ran on a major third dual-tone alert.
Baytown, Texas is one of only a few cities in the United States to have a whole system of Modulators. The city uses just over twenty 5020s and 5020Bs, primarily for notification of chemical releases. The warning tone is a custom Hi-Lo signal.
The Modulators in Olmsted County, Minnesota are known for their pre-test and post-test voice announcements, and also for only being located in parks.
The Modulators in Monroe County, Michigan are known for their pre-test voice announcements. There is a unique "rainbow" Modulator located in Monroe County as well.
Eden Prairie, Minnesota has a uniquely mounted Modulator 5020 on top of a parking garage which has a custom attack tone that cannot be found on other Modulators. This Modulator has never done a voice announcement, which is one of the primary reasons that some cities invest in them.
Additionally, in Cape Town, South Africa, several Modulator sirens are installed which use their standard wail tone to alert citizens in the Melkbosstrand, Duynefontein, Blaauwberg, Table View, Robben Island, Atlantis, Philadelphia and Parklands areas in case of any emergency which can occur at the Koeberg Nuclear Power Station. [4] These Modulators are tested for about an hour annually on the first Wednesday of March during a so-called "Full Volume Siren Test" using a preset female voice (which reads "This is only a test; there is no need to take any action. This is only a test; there is no need to take any action. I repeat: this is only a test; there is no need to take any action. Listen to Good Hope FM or Kfm for further information") and live voice announcements (which are read by people and are often cite similar things said by the preset voice), other than the typical wail tone of the Modulator. [5]
The Modulators (MOD-2008 & 1004) make up nearly all the warning sirens in the Netherlands, which are tested on the first Monday of the month at noon.
The Modulators in Saudi Arabia are located in Air Force Bases in both Riyadh and Dammam.
The Modulators in Branson, Missouri sometimes use live voice with their Whelen counterparts.
The Concrete, Washington area has a system of eight 8032B Modulators to warn of possible breaches at the Baker River Dam. The system uses a distinctive "WHOOP" tone that was originally produced for Federal Signal's line of fire alarms. The system is tested on the second Monday of every month at 6:00pm. [6]
Alaska has many Federal Signal Modulators and Eclipse 8s on their All Hazard Siren System. They sound for tsunamis as well. They use 3012s, 6024s and other potential models. During a tsunami warning, the sirens are activated in attack following a voice announcement.
Langley Air Base has Modulators as a part of the giant voice system at the local Air Force base. The sirens are known to play bugle calls and musical melodies. They play patriotic songs such as The Star Spangled Banner, Wild Blue Yonder, and Taps.
Hawaii has a statewide system of green painted Federal Signal Modulators and Modulator II sirens throughout the state to warn of tsunamis, volcanic eruptions, bomb threats and any other dangerous emergencies or natural disasters. They are replacing a system of old mechanical Federal Signal sirens, such as Thunderbolts, SD-10s, among others, in which a very few still exist due to system replacements by the electronic sirens. Most of the Modulators are dual-tone. The system also consists of EOWS 1212s, EOWS 612s, DSAs, and American Signal I-Forces, mostly running on Siratone and UV controls. Some I-Forces also use the UV Modulator sound cards. The system is tested regularly and are tested both locally by Hawaii-EMA worker(s) and statewide. The Modulators are tested locally, normally started by a worker accessing the controller. They start with the PA feature on the UV by making a live announcement. Then they test every sound on the sound card.
The now decommissioned Pilgrim Nuclear Station in Plymouth, Massachusetts used Federal Signal Modulators and EOWS 612s. They still currently remain standing as of 2023, even though the power plant closed in 2019. They were placed within the towns of Plymouth, Massachusetts, Carver, Massachusetts, Duxbury, Massachusetts and Marshfield, Massachusetts. Their Modulators consisted of 5020s, 3012s, 6024s and 5020Bs. Their EOWS 612 sirens were part of their original SiraTone system and were later on upgraded to UltraVoice controls as the new system utilized them. All sirens sounded in a male voice message that says “ATTENTION! ATTENTION! THIS IS A TEST OF THE EMERGENCY SIREN SYSTEM. THIS IS ONLY A TEST!” The message repeated a few more times and followed by a steady 3-minute alert tone. Testings concluded with another male message (the same voice) that said “ATTENTION! ATTENTION! TESTING OF THE EMERGENCY SIREN SYSTEM IS COMPLETE. PLEASE REGARD ANY FURTHER ALARMS.” The Pilgrim Power Plant never had any major emergencies, but if there was one, the sirens would sound in a tone, followed by a voice announcement. It has been stated that if you hear the sirens/warnings, you would have to evacuate using emergency routes or a ferry to New York City. As of 2023, the sirens are still there, but it is unclear whether they are still active.
Manasquan, New Jersey has a system of MOD-3012s and 6024s. They are similar to the Chicago siren system because they use the rare signal, alternate wail, but after, it includes a voice message that says “THIS IS AN EARTHQUAKE. WARNING! TUNE YOUR AM RADIO TO 1620.” [7] the message repeats at least a few times and then plays the signal.
Severn Estuary has a system of Modulator and DSA sirens. The system runs on both UltraVoice and MCP Controllers. They have very different tones compared to the American ones, potentially custom. The system is activated by radio signal at Avon and Somerset Police headquarters.
Clemson University has a system of MOD-5020s, MOD-4016s and 2001s. They test at the same schedule as the city of Clemson, South Carolina’s psiren system for the nearby power plant. When testing, the modulators normally play a voice that says “THIS IS A TEST OF THE CAMPUS EMERGENCY ALERT SYSTEM. THIS IS ONLY A TEST.” which is followed by attack mode. [8] When a thunderstorm is detected, the modulators sound in hi-lo followed by a voice that says “LIGHTNING WARNING! CLOUD TO GROUND LIGHTNING IS EXPECTED IN THE AREA. PLEASE SEEK SHELTER IMMEDIATELY!” [9] When a tornado warning occurs, the Modulators sound in attack, followed by a voice warning that says “A TORNADO WARNING HAS BEEN ISSUED FOR CLEMSON UNIVERSITY. PLEASE SEEK SHELTER IMMEDIATELY!” [10] The system is not only used for tornadoes, and severe storms, therefore, it is also used in case of an emergency at the power plant nearby the facility. All of the Modulators are ran on UltraVoice controllers.
Little Silver, New Jersey has a system of two Modulator 2008s and one 3012. These Modulators are unique because they play off a custom air horn recording rather than the standard UV/MCP files even though Little Silver never had an actual horn system prior to the Modulators. These sirens replaced a Federal Signal SD-10 and a Model 2. These sirens are used for calls, funerals, Santa escorts, flooding, curfews, blackouts, and natural disasters such as hurricanes and tornadoes.
Point Pleasant Beach, New Jersey has a Modulator 3012 that plays off a Gamewell Diaphone recording in addition to a custom attack tone used primarily for calls even though Point Pleasant Beach never had a Gamewell Diaphone. However, the 3012 got replaced with a 3012b in January 2024 so it is unclear if it still has that tone.
Several controllers were made to run the Modulator sirens. These include the MC (Modulator Controller), MCP (Modulator Power Plus Controller), and UV (UltraVoice). The older SiraTone controller can also run on Modulator sirens but the SiraTone was mainly used on the predecessor EOWS Series sirens. All of the controllers built for the Modulators can be compatible with the Predecessor EOWS sirens, the Successor Modulator II sirens, and the DSA sirens. The Modulator II series started production in 2013 and the older Modulators started production in 1991. The reason why the EOWS sirens can be compatible with these controllers is because the EOWS 408, 812, 115, and 1212 lasted production until 2001. The EOWS 612 was kept in production only on special order until August 3, 2007. All 3 controllers were being made or were made at the time so Federal Signal decided to make the EOWS sirens compatible with these controllers.
The MC Controller came out around 1990 when the Modulator series were being produced. The controller was a microprocessor operated platform which used digital, solid state systems to produce the 7 signals provided by Federal Signal. Unlike the SiraTone, the MC had tones pre-loaded onto an audio ROM chip so there was no need for an analogue tone generator and timer circuit. Audio from the ROM chip was programmed by Federal Signal, with the auxiliary tone being Westminster Chimes by default unless a different tone was requested for by the customer. This could be overwritten by an engineer using software on site, should signaling needs change. The system was activated by two-tone or by DTMF by the controller's internal radio, locally by keying in a two digit code on the controller's keypad, or by operating the controller via landline. When using two-tone or DTMF, the siren has to be "armed" in order to operate (unless programmed not to). To do this a DTMF arm string would first be broadcast to the controller, then a signal DTMF string would be broadcast. Arm period would last for 5 minutes until automatic disarm, unless a "disarm" DTMF string was broadcast before the time expired. This is different, and more secure, to the SiraTone which required a jumper to be added in order to permanently arm the controller. After a signal was activated the digital audio was sent through a digital/analogue converter to each amplifier and onto the speaker array in the form of a square wave. The MC was discontinued in 1996 when it was upgraded to a newer version, the MCP.
The MCP or Modulator Power Plus Controller controller was pretty much the same thing as a MC except there were a few additions. More signals could be generated through the tone generator, and it could also be activated by Federal Signal's FSK (Frequency Shifting Keys) activation tones. Nothing else changed between the MC and the MCP. The MCP was discontinued around 2002 for the newest version of the series, the UV controller. [11]
The UV or UltraVoice Controller is the newest electronic siren controller made by Federal Signal. It now is compatible with the newer type Modulators, the Modulator II series which started production in 2013. The UltraVoice comes in 2 variants: UV and UVIC. The UV is for outdoor use with large speaker arrays like the Modulator, where the UVIC is for indoor use with small speakers and/or intercom systems. UV is capable of holding up to 8 UV400 400 Watt amplifiers, for a total of 3200W. The UV comes standard with 7 signals: Steady, Wail, Alternate Steady, Alternate Wail, Pulsed Steady, Pulsed Wail, and Westminster Chimes. It is offered from the factory in Single or Dual tone, however it is easily changeable after purchase.
Dual-tone multi-frequency signaling (DTMF) is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use in push-button telephones supplied to telephone customers, starting in 1963. DTMF is standardized as ITU-T Recommendation Q.23. It is also known in the UK as MF4.
A civil defense siren, also known as an air-raid siren or tornado 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.
The Emergency Broadcast System (EBS), sometimes called the Emergency Action Notification System (EANS), was an emergency warning system used in the United States. It was the most commonly used, along with the Emergency Override system. It replaced the previous CONELRAD system and was used from 1963 to 1997, at which point it was replaced by the Emergency Alert System.
The Emergency Alert System (EAS) is a national warning system in the United States designed to allow authorized officials to broadcast emergency alerts and warning messages to the public via cable, satellite and broadcast television and both AM, FM and satellite radio. Informally, Emergency Alert System is sometimes conflated with its mobile phone counterpart Wireless Emergency Alerts (WEA), a different but related system. However, both the EAS and WEA, among other systems, are coordinated under the Integrated Public Alert and Warning System (IPAWS). The EAS, and more broadly IPAWS, allows federal, state, and local authorities to efficiently broadcast emergency alert and warning messages across multiple channels. The EAS became operational on January 1, 1997, after being approved by the Federal Communications Commission (FCC) in November 1994, replacing the Emergency Broadcast System (EBS), and largely supplanted Local Access Alert systems, though Local Access Alert systems are still used from time to time. Its main improvement over the EBS, and perhaps its most distinctive feature, is its application of a digitally encoded audio signal known as Specific Area Message Encoding (SAME), which is responsible for the characteristic "screeching" or "chirping" sounds at the start and end of each message. The first signal is the "header" which encodes, among other information, the alert type and locations, or the specific area that should receive the message. The last short burst marks the end-of-message. These signals are read by specialized encoder-decoder equipment. This design allows for automated station-to-station relay of alerts to only the area the alert was intended for.
Specific Area Message Encoding (SAME) is a protocol used for framing and classification of broadcasting emergency warning messages. It was developed by the United States National Weather Service for use on its NOAA Weather Radio (NWR) network, and was later adopted by the Federal Communications Commission for the Emergency Alert System, then subsequently by Environment Canada for use on its Weatheradio Canada service. It is also used to set off receivers in Mexico City and surrounding areas as part of the Mexican Seismic Alert System (SASMEX).
A siren is a loud noise-making device. 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. There are two general types: mechanical and electronic.
An emergency population warning is a method where by local, regional, or national authorities can contact members of the public to warn them of an impending emergency. These warnings may be necessary for a number of reasons, including:
A weather radio is a specialized radio receiver that is designed to receive a public broadcast service, typically from government-owned radio stations, dedicated to broadcasting weather forecasts and reports on a continual basis, with the routine weather reports being interrupted by emergency weather reports whenever needed. Weather radios are typically equipped with a standby alerting function—if the radio is muted or tuned to another band and a severe weather bulletin is transmitted, it can automatically sound an alarm and/or switch to a pre-tuned weather channel for emergency weather information. Weather radio services may also occasionally broadcast non-weather-related emergency information, such as in the event of a natural disaster, a child abduction alert, or a terrorist attack.
A fire alarm system is a building system designed to detect, alert occupants, and alert emergency forces of the presence of fire, smoke, carbon monoxide, or other fire-related emergencies. Fire alarm systems are required in most commercial buildings. They may include smoke detectors, heat detectors, and manual fire alarm activation devices. All components of a fire alarm system are connected to a fire alarm control panel. Fire alarm control panels are usually found in an electrical or panel room. Fire alarm systems generally use visual and audio signalization to warn the occupants of the building. Some fire alarm systems may also disable elevators, which are unsafe to use during a fire under most circumstances.
In a conventional, analog two-way radio system, a standard radio has noise squelch or carrier squelch, which allows a radio to receive all transmissions. Selective calling is used to address a subset of all two-way radios on a single radio frequency channel. Where more than one user is on the same channel, selective calling can address a subset of all receivers or can direct a call to a single radio. Selective calling features fit into two major categories—individual calling and group calling. Individual calls generally have longer time-constants: it takes more air-time to call an individual radio unit than to call a large group of radios.
The Motorola Minitor is a portable, analog, receive only, voice pager typically carried by fire, rescue, and EMS personnel to alert of emergencies. The Minitor, slightly smaller than a pack of cigarettes, is carried on a person and usually left in selective call mode. When the unit is activated, the pager sounds a tone alert, followed by an announcement from a dispatcher alerting the user of a situation. After activation, the pager remains in monitor mode much like a scanner, and monitors transmissions on that channel until the unit is reset back into selective call mode either manually, or automatically after a set period of time, depending on programming.
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.
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.
The Mount Rainier Volcano Lahar Warning System consists of two separate components, operating in tandem: Acoustic Flow Monitors (AFM) and the All Hazard Alert Broadcast (AHAB) sirens. The AFM system was developed by the United States Geological Survey (USGS) in 1998 and is now maintained by Pierce County Emergency Management. The purpose of the warning system is to assist in the evacuation of residents in the river valleys around Mount Rainier, a volcano in Washington, in the event of a lahar. Pierce County works in partnership with the USGS, the Pacific Northwest Seismic Network (PNSN), Washington Military Department's Emergency Management Division, and South Sound 9-1-1 to monitor and operate the system.
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 ATI Soundblaster HPSS is an electronic outdoor warning siren manufactured by Acoustic Technology, Inc that is used to alert citizens of air raids, natural disasters and so on. The recent HPSS systems use high-powered electronic speakers, which can be independently arranged to provide directional or omnidirectional coverage, depending on installation. The HPSS16 have 4 speakers and the HPSS32 have 8 speakers. They can also be used as public announcement (PA) systems, and can play a number of programmed tones. Options include solar-powered operation pre-recorded voice messages. ATI also sold rotational units of the HPSS16, and HPSS32, called the "HPSS16R" and "HPSS32R", that are now discontinued.
The Public Warning System (PWS) is a network of civil defense sirens installed by the Singapore Civil Defence Force on over 2,000 strategic points in Singapore to warn Singaporeans of impending dangers, air raids and atomic bomb blasts. Thus far, the siren network has only been used for occasional public awareness drills, monthly noon chimes and for commemorating the island's Total Defence (February 15) and Civil Defence Days (September 15). It was also used to mark a minute's silence nationwide for the passing of former prime minister Lee Kuan Yew on the evening of 23 March 2015 and on 1 and 9 August 2020 to mark the first National Day at home.
The Local Access Alert is a warning system designed to warn radio, television stations, cable television broadcast feeds or satellite signals of impending dangers, such as tornadoes, flash flooding and other civil emergencies. The system was largely replaced by the Emergency Alert System "[1]". in the United States, although it still exists in some areas which have not yet been upgraded, and is still used from time to time in areas that have upgraded to the EAS.
The Severnside Sirens are a system of Civil defense sirens located along the South Severn Estuary coastline from Redcliffe Bay to Pilning, northwest of Bristol. They are activated by Avon and Somerset Police in the event of a potential incident at one of the COMAH sites located in the area, mainly in and near Avonmouth. The system was setup in 1997 following a fire at the Albright and Wilson site in 1996.
The Thunderbolt is a discontinued mechanical outdoor warning siren made by Federal Signal Corporation. it is a unidirectional siren with a large yellow horn.
