Siren False Activation; Appalachian State Univ, Boone.

[kb4mdz]

Happened Sunday Oct. 27th, 2013:

http://www2.wataugademocrat.com/News/st ... -id-012998

Hmmm, understanding controls a little better than a reporter probably does, (just sayin') I think she's got a few things not quite right in the article, but newspaper articles aren't about technical details.

I know they have at least 2 units, maybe 3. Don't know whether it was just 1 unit activated, or more.

Now, they need to properly maintain & manage those UPS's.

Whelens, FWIW.

Chuk

[theroofable]

If they are radio controlled, some receivers don't have PLs. With the right conditions, a set of tones many miles away could set off the siren. One of the reasons why dtmf activation is better for siren controls.

[CrazyCalvinWilliams]

Like, if I put tones through my CB radio, it might activate a siren? :eh:

[djscrizzle]

Many sirens installed nationwide, where radio-controlled, used to or still generally run in three areas on the RF spectrum: Lo-Band, in the tens of Mhz - VHF at the 2 meter range, 140-160 MHz, and then, 800MHz as part of a metro area's trunked radio system, riding along with a virtual channel.

[holler]

We've had power surges and nearby lightning strikes cause sirens to false in our area. A big surge can make all sorts of weird stuff happen.

But I don't see how that would affect a Whelen, since the radio runs off battery power, and those batteries act as big smoothing capacitors and absorb all incoming surges and transients.

With that being said, we had an older Vortex (440hz controller) that went nuts and would randomly go off at 3 AM in air horn. Sent the front panel to Whelen and they found a raw place in the ribbon cable that runs from the membrane switch to the control board. They also performed a front panel upgrade while they had it and we haven't had anymore problems with the siren. The bare spot in the cable would ground out against the aluminum front panel and make the siren think that a button on the membrane switch was being pressed.

[dclarkct]

Purely speculation because I don't know the system. If they know what controller sent the message then it must have been a controller malfunction. Maybe a contact closure on the remote inputs? If they use a relay and the power got a spike then that could cause a false activation.

[holler]

Could they have interfaced the siren controller with the F.A. panel somehow? F.A. panel goes nuts and off goes the siren.

[kb4mdz]

Interesting speculations here, but they're pretty much moot, without knowing more.

Yeah, the reporter probably has zero technical background, and phrased the article in such a generic way that a non-siren-geek could be satisfied that things will get straightened out.

Us, on the other hand.....

I could send my daughter over there to ask (she's a senior there), but they would probably look at her, 9 versions of sideways and say "Why in hell are you asking??? Are you some kind of nut-job? Some kind of terrorist? GO AWAY!! You don't need to know!"

Being the snarky kid she is, she'd probably tell them "Yes, I'm a nut-job, but not about sirens. My dad is the nut-job about sirens. And no we're not terrorists. But technical problems are great fun to chase down!!"