So apparently they've put in a new siren notification system near where I live. Almost right next door to where I live as it happens to be. I was able to get the initial test on video today. They use 158.8575 D031 to activate the sirens.
Providence Journal Article
Sorry the pictures aren't clearer.
This is the one next to me on Pawtucket Ave in East Providence/Riverside.
Here are the tests from my rear deck.
http://www.youtube.com/watch?v=Twmh3RfNAeY
http://www.youtube.com/watch?v=BiueBvRF3tQ