"This siren is about to activate" notification.

[SoundOff]

The Chino Prison's community alert siren system has one feature that I don't think is employed on other siren systems; a pre-activation warning. Originally, the prison wanted to use small area sirens (The Federal Signal Select-Tone) as part of their community warning system but they turned out to be too small for the job so 2001 SRNBs were then installed.

The last couple times I visited CIM to listen to their siren test, I noticed the Select-Tones were also used again but they would activate along with the blue strobe lights and play a slow "whooping" tone for 4 cycles then the main 2001-SRNB Sirens would go off.

I made another recording of the same siren I did last September but I started my camera early in order to capture the pre-activation signal. I don't think there is any other outdoor warning system that would actually announce to people nearby that the siren is about to sound.

http://www.youtube.com/watch?v=LPN9wLyvY-c

The only thing I could think this is useful for is to tell me when to start recording although it may also be used to warn people near siren sites (especially the one off El Prado road which less than 15 feet off the ground) that they are about to get blasted.

[coyoteunknown]

Turkey Point also gives notification before the actual test begins. They use a system of Whelen with voice capabilities.

"The test of the Turkey Point warning sirens will begin shortly. This is only a test."

http://www.youtube.com/watch?v=fV39jLuF ... re=related

Edit:

Here's another video of Lakewood's solar powered Whelen 3016's giving notification before sounding a test.

"Attention. This is a test of the Lakewood outdoor warning system. This is only a test."

http://www.youtube.com/watch?v=EDONckvUEBE

[ver tum]

I did see a video on YouTube a while back, where some Thunderbolts growled briefly before sounding at full blast. If memory serves me correctly, it seems that this was done to warn people to bring in their dogs, so the sirens wouldn't hurt their ears. I remember them calling it a hum.

I've also heard of some rotational sirens, that start rotating a fiew seconds before they sound. This would be helpful if you can see the siren, but if the siren is hidden in some trees, or if you're visually impaired, you would still get blasted with no warning.

[bobc455]

When we were much younger, we were camping at a military academy. As we were walking along, one of the other Scouts heard a slight clicking noise coming from this funny-looking thing. None of us knew what it was until he stuck his ear next to it, only to find out that it was the camp's PA system, and it blasted all of our eardrums out.

Having a quite voice saying "I'm about to be really loud" would have kept our hearing more intact.

-BC

[AllSafe]

When the controller is brought online for a tone activation on one of the pre-Ultravoice Siratone 412s, 612s and 812s, it will rotate the siren head for a few seconds as a visual indication that the controller is ready to accept the command to activate a certain tone. This certainly can act as a preemptive warning of activation because it takes a few seconds afterwards to send the proper DTMF sequence to activate the tone.