Effectively nothing. I dug into this and found this article (1) from earlier this month on the FCC targeting a couple pirate radio stations in and around NYC. It says they used field agents and FM directional finding equipment to locate the signals to specific property. Probably a big show of force operation on their part.

However, the buck stops exactly there. It becomes the landlords issue, not the tenant who might be operating the radio, where the property owner is liable to be fined if they themselves don't shut the signal off after a certain amount of time. I would guess the FCC lacks the sensitivity to target the signal to a specific unit in a given building in order to issue the fine directly to the involved individual.

I guess the lesson is you can do whatever you like as long as you have the actual radio mast on someone else's property as they will get the fire if the FCC bothers to show up.

Makes me wonder about those old FM radio dongles we had for cars that lacked aux jacks or tape decks if those would technically be pirate radio. You'd have to set them to whatever open channel was locally available and they had actually pretty good range; I remember picking up my friends signal while I was driving behind them.

1. https://www.insideradio.com/free/pirate-radio-crackdown-puts...

You're right that most amateur radio regulations are self-policed by other amateur radio operators, and true enforcement is probably rarer than folks like to imagine.

But depending on the environment (and noting that this project is specifically targeted towards communities seeking last-resort communication), there's definitely still risk, even if there isn't a spectrum authority with any real policing powers.

For example (and I say this speculatively), if you're broadcasting encrypted radio traffic in a conflict zone, it could be hard to differentiate between civilian traffic and military traffic happening on civilian bands, so you might be wrongly targeted by a drone strike.

If you already have a target on your back, radio laws can still be arbitrarily applied upon oneself, as in the case of Aung San Suu Kyi, who was once detained on the pretense of illegally importing handheld radios. [1]

[1]: https://apnews.com/article/aung-san-suu-kyi-myanmar-asia-ap-...

If you're curious what's allowed on the ham bands, have a listen to 7.200 MHz LSB. (If you don't have a receiver, try one on the web[0], such as this one[1].) As of writing, someone is spamming the channel with racial slurs and KKK propaganda using a soundboard.

In my experience, enforcement of the rules is unheard of.

[0]: http://websdr.org/ [1]: http://websdr.k3fef.com:8901/

In the US, FCC investigations are complaint-driven. Meaning, if you interfere with someone else's frequency, and they complain about it hard enough, the FCC will take an interest in you. Especially if you interfere with public safety. (But they will still go after the more flagrant and persistent abusers on the ham bands.)

In practice very little. The FCC tends to focus on long-lived stationary stations ("pirate" radio) with their few enforcement actions. That said it's important to remember that radio transmissions can easily be tracked to their source (doubly so with drones) and you should plan for that eventuality.

My sense is that at most you will be yelled at by HAMs - unless you are actually disrupting emergency communications. Ensuring radios can be used in emergencies is why licensing exists at all and people take ensuring it can be used for that pretty seriously (for good reason).

> what would happen if you were to break that law? like im talking enforcement here not whats on the books.

In the UK, nothing. There are far more important laws to enforce.

You will get some fat whiny old guy bitching about it to anyone who will listen, but you literally could not pay Ofcom to take an interest, and there are only about two people in the whole of the UK who have the skill to do anything about it.

You really only need authentication for that, not encryption. MACs and such are okay on ham bands as I understand it. You just can't obscure the message. If you want a private channel to the exclusion of other people, license a frequency and pay for it. Spectrum is a scarce resource.