4 digit code on 144mhz -- just sending a code alone triggers alert? Wouldn't it need a payload to describe the msg?
As far as I'm aware this is still the case - but some sites are now encrypted radio. From what I've heard though, that encryption may not be the best implemented in all areas.
It was pretty recently someone set off the civil warning sirens in I believe a city in Texas via this method as well.
I'd like to say this was a one off experience in my "exploring civil infrastructure" days - but it's really just barely scraping the surface. The state of these systems makes you realize how much civilization is held together with tin cans and duct tape, and how much marketing fluff there truly is out there inspiring false confidence.
I'm assuming this was from the past ("when i was a teenager") when the messages were much more generic and fixed than they are today.
It definitely is from my teenage years but whenever I visit folks I drive by that tower a block away. You can tell nothing has been upgraded
Smart system, really. Very simple to install/maintain and very simple to have a robust transmitter infrastructure around.
If you just substitute your 4-digit code for a longer, say, 64, digit one with some time-based component, and perhaps shift the required frequency too based on time, you actually end up with a very robust very simple system.