Federal Signal Modulator

A Federal Signal Modulator siren in Bay Head, NJ.

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 or any other disaster. They are identified mostly by their distinctive stacked "flying saucer" design. The Modulator II is more sold on the side of the siren.

General Description

The Modulator is composed of speaker cells (ranging from one 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 available. Modulators have an inactive (dummy) speaker cell on the bottom of the stack that is used to help project sound in all directions. Without the inactive cell, because of the design of active cells, there would be unbalanced sound distribution.

Models

Modulator model numbers identify the number of cells, as well as the number of drivers. The family of Modulator array are made up of eight different models, as follows: 1004, 2008, 3012, 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. 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

Like Federal Signal's previous Electronic Outdoor Warning Siren series, the Modulator can produce seven standard warning tones. The seven standard tones are: Steady, Wail, Alternating Wail, Fast Wail, Alternating Steady, Pulsed Wail, Hi-lo, and Pulsed Steady. 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. For testing purposes, a Westminster Chime can be played. They have also been known to play Star Spangled Banner during tests on or near the 4th July, and also on military bases that have the sirens there.

Similar Devices

The Modulator has 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. Another siren that is similar to the Modulator is the American Signal I-Force siren, which uses stacked, elliptical speaker cells that provide omnidirectional sound output, just like the Modulator.

Notable Locations

Chicago, Illinois is famous for their Modulators. Their sirens run on the noticeably different and somewhat off-putting Alternate Wail tone during tornado warnings, often mistaken for a broken siren.

Moore, Oklahoma is well known for their Modulators being placed really close together compared to other cities. They're placed only a half mile from each other in some parts of the city. Until 2017, some sirens ran on a Major 3rd dual tone alert.

Baytown, Texas is one of only a few cities in the United States to have a whole system of Modulators. They use just over 20 5020's and 5020B's, and use them primarily for chemical releases.

The Modulators in Olmsted County, Minnesota are famous for their pre-test and post-test voice announcements, and also for only being located in parks.

The Modulators in Monroe County, Michigan are extremely well known for their quite irritating pre-test voice announcements. There is a unique "rainbow" Modulator located in Monroe County as well.

Eden Prairie, Minnesota has a uniquely mouted Modulator 5020 on top of a parking garage which has a custom attack tone that cannot be found on other Modulators. Strangely, 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 (of which Van Riebeeckstrand is part of), Duynefontein, Blaauwberg (of which Bloubergrant, West Beach, Blouberg Sands, and Sunningdale are part of), 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 (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.