Federal Signal Modulator
Image:Bayheadmod.jpg|right|thumb|200px|A Federal Signal Modulator siren in Bay Head, New Jersey.
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.
Description
The modulator is composed of speaker cells that contain four speaker drivers per cell, although two models had additional drivers available when they were still produced. Modulators have an inactive 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 and basic/standard Modulator Controls.Models
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.
Warning tones
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. 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 The 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.
Similar devices
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, 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.Notable locations
Indonesia
The Modulators in Indonesia are used as a tsunami warning system following the 2004 Indian Ocean earthquake.Malaysia
The Modulators in Malaysia are located in Gong Kedak Air Force Base in Gong Kedak near Kelantan-Terengganu border. It is visible from the Google Street View via Jalan Seberang Jertih near the entrance of the air force base.Netherlands
The Modulators make up nearly all the warning sirens in the Netherlands, which are tested on the first Monday of the month at noon.Saudi Arabia
The Modulators in Saudi Arabia are located in Air Force Bases in both Riyadh and Dammam. Replaced older ACA Cyclone 120-CsSouth Africa
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. 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 and live voice announcements, other than the typical wail tone of the Modulator.United Kingdom
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.United States
Alaska
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.Hawaii
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 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.Illinois
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 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.Massachusetts
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 that said “ATTENTION! ATTENTION! TESTING OF THE EMERGENCY SIREN SYSTEM IS COMPLETE. PLEASE DISREGARD 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. As of 2023, the sirens are still there, but it is unclear whether they are still active. However, in a couple of the towns, they are active.Michigan
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.Minnesota
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.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.
Missouri
The Modulators in Branson, Missouri sometimes use live voice with their Whelen counterparts.New Jersey
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 A HURRICANE WARNING! TUNE YOUR AM RADIO TO 1620.” the message repeats at least a few times and then plays the signal.Little Silver, New Jersey has a system of two Modulator 2008s and one 3012. They were installed in 1999 and 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. However as of 2025, they have been updated to a new shorter tone due to most likely a blown sound file in the longer original tone from 1999.
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.