[zorm]

There were mentions of the repeater system last night, so my guess is they transmitted weakly somewhere and the repeater happily repeated it out to activate all the sirens.

You can do this pretty trivially with HAM gear, although some may require small modifications to allow transmitting on the necessary frequencies. You can also often buy the equipment on ebay ready to go.

[cyberpunk]

I didn't see that got a link?

I sort of felt (in my ignorance of such systems) that this would have been somehow relayed / repeated instead of being a broadcast across an entire city but I didn't want to speculate as I'm clueless on this kind of tech.

I know it's a nuisance, but this is the sort of thing I daydreamed about doing when I was 13 so I can't help but be kind of entertained by it (at least while the only fallout appears to be knocking people out of bed).

[jcrawfordor]

The city has licenses for repeater-equipped public service frequencies, so it's definitely a possibility. That said all of those licenses seem to be either trunking systems or attached directly to various departments that are not OEM who operates the sirens - so possible, I'm just thinking the pager system is most likely.