Unexplained Sound on Lake Geneva Fire Freq

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wx9kvh

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I have been hearing this burst of noise on lake geneva fire's main dispatch frequency for a couple of days now, and i cannot figure out what it is. Whats weird is that it is on frequency with an exact pl tone of 136.5. I have ran through all possibilities and have come up stumped. Its completely random as well. No set time is plays and when it does it plays it twice(the recording provided is the second half of the two.) And i have listened for up to 15 min after and theres no more activity. No one talking(as if the tones were for an air raid siren, usually there would be a call dispatched shortly after)

Any ideas would be appreciated. Thanks.
 

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milaw

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That is what our outdoor warning siren signals sound like when they check themselves. Everynight around 2am our system communicates with the individual sirens to make sure everything is ok. I am not sure exactly how or what it does but that is what it sounds like.

My wife works in our dispatch center and she heard me play your file in the other room, "hey, that sounds like the sirens polling..."

This is what the controller looks like if it helps - Outdoor Warning SS2000 DTMF Siren Encoder/Decoder Description
 

wx9kvh

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Response to MILAW

Wow, this is pretty cool info. Your wife working in lake geneva and having seen this is pretty cool as well. I heard it at 630ish pm tonite so i dont know if it checks after fire calls or whatnot, but i do appreciate the quick responses. Thanks again.
 

ToDaMax

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I've never heard a siren sound like that on startup, and sirens dont usually go off at random times unless there is a fire call, and in that case the siren would be a tone. It could be radio tech's messing with the siren, maybe somthing with the narrobanding
 
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OpSec

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Wow, this is pretty cool info. Your wife working in lake geneva and having seen this is pretty cool as well. I heard it at 630ish pm tonite so i dont know if it checks after fire calls or whatnot, but i do appreciate the quick responses. Thanks again.
He is Michigan, not Wisconsin...I think a few people are getting their wires crossed (no pun intended) here. His wife probably recognized the sound because her city or county uses a similar system so it sounds the same.

A modern outdoor warning system is comprised of an encoder of some sort at the PSAP (and backups off-site usually) and decoders at each of the noise makers. When the dispatcher pressed the big red button, the encoder sends out various data bursts via radio or wireline to each of the sirens to start them up or shut them down. In reality, it's a two-way conversation so there is usually a lot of squawking...especially in a big city that has a lot of sirens. The systems I am familiar with have a typical 25w or 50w mobile radio mounted at the PSAP and in each siren control cabinet so they can communicate back and forth.

Back when the outdoor warning system was built out in the 50's during the Cold War there were initially 3 choices: Alert, Attack and Cancel/All-Clear but then the Cancel/All-Clear was deleted leaving just Alert and Attack. Alert is a steady tone (mechanical siren rotor winds up and stays at max RPM) and Attack is a wailing rising/falling tone (mechanical siren rotor RPM varies as motor powers up/shuts off in sequence). Currently there are also test modes like the silent test that make the siren head rotate but not power up the rotor, or the full test that everything powers up for a couple seconds and then shuts down.

In order for the newer sirens to know which mode to operate in, the encoder sends out different sets of data depending on what the operator wants them to do. They also send out the polling data on regular timed intervals and then report back if any of the units failed or didn't respond. If you listen to the process on a regular basis and live by one of the sirens in question, you will know what the sirens are doing just by the type of data bursts after a while. Some of the systems have an external control box like shown in the link above, or some are interfaced into the dispatch console. The data types vary also and range from DTMF, FSK or two-tone. I got a old Motorola Intrac two-tone encoder interfaced into a Centracom console as part of a surplus acquisition a while ago, and even though it's 30 plus years old it could still be used. The better part was the Centracom interface that says "TORNADO", "ATTACK" and "CANCEL". Older systems like the Intrac don't do remote polling, just the newer FSK system as far as I know.

I think Federal Signal, American Signal and Whelen are probably the 3 big outdoor warning equipment sources these days, plus just about everything is electronic now but there are still plenty of mechanical sirens around (which sound better IMHO).

Google "outdoor warning sirens" or similar if you really want to get your nerd on...I'd go on for pages but I'll suppress my inner demons :)
 
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ToDaMax

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After some searching, I have found that the 15 second audio is indeed a siren polling (Although I've never personally heard a siren data burst like that). The only sirens data sound I've heard from polling were Milwaukee County's siren polling, and a second polling sound heard from many youtube videos that I've heard now and then on my personal Scanner.

They were probably testing it because it might have been a new siren or a malfuncion of a current siren, which would explain the randomness. What they were doing, I dont know, but it is a siren polling you are hearing.

Audo/Video of siren polling that I speak of, including the one in question, can be found below. NOTE: I own none of these videos

Audio in Question: Siren polling - YouTube
Milwaukee County's : ASC Compualert Polling - YouTube
Common Polling Sound: March 28 Tornado Drill (Scanner) - YouTube
 
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OpSec

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Somewhat related: does Lake Geneva use an outdoor siren as part of it's fire call alerting process?
 

johnnyfive12

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I work for Lake Geneva Fire and it is a test of the storm siren system. It happens everyday at 6:30 PM. Also the city does not use the siren system to summon firefighters to the station. City of Delavan still does though I think
 

mkescan

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Some agencies do that testing around 2am. Milwaukee County Emergency Managagment on 453.375 (136.5) Couple of Waukesha County depts do them too on a talkgroup.
 

ToDaMax

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In Ozaukee, the sirens are operated through the county paging system, by the county's EM. One of Mequon's sirens (next to the PD) is tested every morning at 0915; a quick system check and wind up, but no actual test. Sirens are also sounded at Noon (although I dont know where they are sounding, only hearing data through the pager)

I do not know if there is any use of fire sirens in Ozaukee; everyone has a pager or department radio now, but they could still be used, especially in northern Ozaukee. Mequon does not use them (that i know)
 
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