Siren Activation

[Melvin Potts]

On the first Saturday of April I decided to observe the Brentwood, TN monthly siren test.

Except for 3 Modulators in city parks, the system is Federal 2001s(11 of them). It was installed about 6 or 7 years ago.

The system is tested on the first Saturday of each month at 1 P.M. I'd heard the siren at Brentwood Municipal Building a few times during severe weather alerts(building where I work is only about 4 buildings from there).

On April 7th I parked my car at a shopping center across the road from one of the 2001s; wanted to watch it rotate as it sounded.

The test is supposed to be for 1 minute.

I heard a distant siren start up and go through almost 1 complete wail cycle before the Moores Lane siren started.

Somehow I recall reading on Federal website that the 2001(at least the older models) normally rotated at 2 RPM, but that was adjustable.

The Moores Lane siren made one complete clockwise revolution; it made about 3/4 of another turn before stopping.

These sirens must be on radio control, because I noticed an antenna on the pole.

Now..I'm curious. In a radio control activated system, why didn't the siren I was observing start until several seconds after another one?
Any ideas, information, etc.?

[Rheems1]

Is it possible that each siren has it's own DTMF tone? Maybe the first siren you heard was one of the first ones in the system and the one you were at was near the end..... the old control panel for the Three Mile Island Nuclear Power Plant system was like this... all 79 sirens had it's own DTMF tone and the numbering of them made no sense... so it was very possible to have a siren 2 miles away start up and be standing at one and not have it go until a minute to a minute and a half later (sometimes more).

Dave

[gil64]

The new 2001's here in my city have those antennas you are talking about . Check out the pic below and you can see it.