ARES has made me curious

[N9ZHW]

With the severe weather week and drills approaching, there's 1 thing I've always wondered: I've never quite understood how they set the weather warning sirens off in the counties. Is it simply transmitting the right tones over the dispatch tower at the right frequency similar to an autopatch phonecall through a repeater? Is this the same way that the fire/EMS stations that still use horns to alert their members out in the country activate them? I always understood this was all manual -that someone had to physically go and turn the thing on at the site. (At least that's how our fire horn used to operate, but that was about 30 years ago!) 

[W3JKS]

With the severe weather week and drills approaching, there's 1 thing I've always wondered: I've never quite understood how they set the weather warning sirens off in the counties. Is it simply transmitting the right tones over the dispatch tower at the right frequency similar to an autopatch phonecall through a repeater? Is this the same way that the fire/EMS stations that still use horns to alert their members out in the country activate them? I always understood this was all manual -that someone had to physically go and turn the thing on at the site. (At least that's how our fire horn used to operate, but that was about 30 years ago!) 

Some areas use tone activation, others systems like Motorola's MOSCAD.  Depends on the area. 

[N2HBX]

Here in Winter Park, FL a data stream sent over a Public Safety radio channel activates the sirens. The data side was designed by Federal Signal, and the Motorola shop I work for did the RF integration.

73,
Larry, N2HBX

[W5LZ]

Mark,
Didn't see this earlier so your question has already been answered.  Very basically, activating those sirens can be done in several different ways, almost anything you can imagine.  At one point the local ones were activated by tones on a phone line connected to all of them.  Later, the same sort of thingy except via RF.  What's the 'best' way?  Whatever is most convenient for the user.  There are 'catches' with any system so it's just whichever 'catch' you can live with the easiest.
 Paul