Siren Activation Channels

[tunneltrain96]

Hey there,

I have a simple question. What types of channels/frequency types are siren activation tones usually transmitted on? Currently, my best guess that I've tried to use is fire dispatch, or a dedicated activation frequency if it's listed on places like RadioReference.

However, I've had speculation that some counties/areas might use other types of channels, such as police dispatch. It's hard for me to confirm this, but with what I encountered during a test in Paris, Kentucky, it makes me a little more confused. In case you haven't watched my video on it, I'll explain.

When I arrived at the siren location, I set up my gear and got out my scanner. I tried looking for several frequencies that could be used in Bourbon County. Since a public safety officer was present during the test, I was questioning if the fire dispatch frequency would actually be used. Once the test began, I tried looking through other police frequencies to see if they would provide anything, but I had no luck.

Another occurrence was with Madison county Kentucky. I tried tuning in to the EMA frequency, but I heard nothing except some odd static every now and then. (it was also picking up EAS SAME tones at around the same time as the test time!) Since the siren didn't sound at all, I thought the fact that I heard no DTMF could've explained that a little.

Despite being an avid videographer and photographer of Fayette county's siren system, I haven't found an activation frequency for here since I believe they have the activation frequency outside of the hearable band. (The system is all mods and a single Whelen WS-2008 so I'm not too surprised)

So since none of the publicly available frequencies I've tried don't seem to have any activity, whether the siren sounds or not, what are the standard frequencies used to hear these activation tones, and are they different from other counties?

[Hacksaw]

There are a variety of frequencies that could be used, like anywhere on the Public Service bands:

30-50 MHz

150-172 MHz

450-512 MHz

700 MHz

800 MHz

They might be using a Public Works frequency, for example. And, some places use frequencies that they don't have an official FCC license for, so reference publications may not help.

[Fireman61341]

They might be using a Public Works frequency, for example.

That's how it was in the city I work for. Dispatch activated the sirens on the same frequency that we talk on and if someone keyed a mic at the same time they were putting out the tones it would interfere with the activation sometimes. They moved us over to a repeater frequency earlier this year so we don't hear it anymore but I assume they're still using our old frequency for the sirens.

[nvanw27]

Sometimes, they're on county frequencies that don't appear on the RR home screen. Other times, they're trunked channels, or are on a state-level communication system that the county uses. Your best bet is to use a scanner with the 'close call' functionality.

[OHIO Desperado]

There are also other options to activate sirens that haven't really been discussed here that I have seen.
First is SCADA / Motorola MOSCAD, which has been renamed to some other product that I can't remember the name to right now. But those are both data systems that connect to the controller board via an AUX interface (on Whelen 2020 / 2030 logic boards) and control the sirens in that manner.
Another way they can be tripped is a trunked public safety system where there is a trunked radio for the system in question. The H/L or horn and lights function is programmed in the radio and the radios are commanded to alert either by a direct to radio ID command or a group call command that switches a pin on the back of the radio to make the siren activate. This would also be done with an AUX board connected to the logic board in a Whelen. Other siren manufactures have direct inputs to do this.
Federal decoders will actually listen for a SAME code from a weather radio and activate off that SAME code.
Lastly, there may still be some wireline controlled sirens that are connected via telephone lines that run directly back to the activation point. That was the standard many years ago.

But DTMF is certainly NOT the only way to activate a siren. There are other ways that it can be done too that I haven't ever touched on.