The Siren Board

I've been meaning to ask a question about these sirens. My understanding is that many electronic sirens use a recording of a mechanical siren when sounding off tornado or air raid alerts. My question is when they are winding up and winding down, is it the recording that is starting and finishing, or do the siren operators have some sort of manual fader control that can windup or wind down the sirens' blaring?

http://youtube.com/watch?v=W03SCw3lB8I

Most electronic sirens have tone generators that produce the sound, rather than a recording (one exception being the ATI's in San Francisco which sound a recording of an STL-10).

Don't forget the county who's people forced the EMO to make their Whelen's sound like Thunderbolts, because of the familiarity of their older system.

I do believe that was a recording, unless it was a fairly convincing tone generator.

what is a tone generator? what does it look like? Is there picture of one?

A tone-generator is computer software that creates tones of your rough specifications and frequencies. I have a free trial-offer one from the NCH website; it is rather fun.

The tone generator I think you would want to refer to is an electronic circuit for producing the sounds. The sound is then amplified and sent to speakers.