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Sending out tones far after testing is over - why?

Posted: Wed Jul 10, 2019 4:29 pm
by CrazyCalvinWilliams
I have the Franklin County siren control frequency (158.925) on my scanner and after the noon test they're still sending out DTMF strings even though the sirens aren't going off anymore.

It's currently 12:30 and they are still sending out DTMF strings as I am typing this. Perhaps they're doing some kind of silent test or addressing an individual siren?

Re: Sending out tones far after testing is over - why?

Posted: Wed Jul 10, 2019 4:41 pm
by uncommonsense
Would seem to me it's likely each individual RTU phoning home. They all can't transmit at once or else you'd just have a bunch of noise on the radio channel that couldn't be decoded.

Re: Sending out tones far after testing is over - why?

Posted: Wed Jul 10, 2019 4:53 pm
by CrazyCalvinWilliams
I didn't think of that. I got it on video: https://www.youtube.com/watch?v=2M3J14iN4Bg

It's currently 12:52 and it is still happening.

Video link is unlisted so only those with link can see btw.

Re: Sending out tones far after testing is over - why?

Posted: Wed Jul 10, 2019 11:46 pm
by nvanw27
Polling the sirens for activation status. With the amount of sirens that county has it would probably make sense.

Re: Sending out tones far after testing is over - why?

Posted: Thu Jul 11, 2019 2:05 am
by CrazyCalvinWilliams
That's what someone else told me on my instagram, siren polling. Didn't know that was a thing until now but makes sense.

Re: Sending out tones far after testing is over - why?

Posted: Thu Jul 11, 2019 2:46 pm
by nvanw27
CrazyCalvinWilliams wrote:
Thu Jul 11, 2019 2:05 am
That's what someone else told me on my instagram, siren polling. Didn't know that was a thing until now but makes sense.
most systems with 2-way communication utilize it for activation status and to make sure sirens work. This is one of the reasons why some systems have individual frequencies so they don't tie up other frequencies.