[lexicalscope]

As I recall, they got around this by not being FCC licensed - in other words, HackRF is classified as a kit/developer component, and is not legal to operate unless you hold an independent license from FCC (e.g.: if you're a Ham you can use it on Ham frequencies you are licensed for). Read the disclaimer at bottom

> HackRF One is test equipment for RF systems. It has not been tested for compliance with regulations governing transmission of radio signals. You are responsible for using your HackRF One legally.

Realistically you're not going to probably get in trouble, but I _will_ caution you - if you use this kind of equipment illegally, the FCC does have radio direction finding equipment and will send someone out to find you if you piss them off - they've done this for people that were on Ham frequencies without authorization, people doing nasty things on government frequencies, and anything disturbing people who paid for a license.

Re: GNURadio The software itself has no requirement - there is no "if you run radio software, it has to do X" and there still is no requirement under proposed rules for that as far as I can tell - it's just if you build hardware, your hardware must enforce that only certain software can be installed :).

[fapjacks]

There seems to be some incredibly bizarre idea floating around here that it is illegal to MONITOR using the equipment (id est "listen") and that is simply not true, except for listening to cell frequencies. That is in American law, but here's the thing: They will not be able to determine that you're listening on those frequencies without looking at your equipment. You can possess and operate your equipment in monitor mode without a license. One must simply get a license (in most countries) to transmit using the equipment. Now, the other thing I want to mention is that the parent comment is right that the FCC has dogs of war that will chase you down and put you in jail (or levy heavy fines) for operating without a license. And they do chase people down with location equipment. I'm not advocating operating a station without a license, but if you keep the power very low and use it sparsely for testing, you have a very, very small chance of being caught by the FCCs enforcement arm. And in most of these cases of nerds transmitting without a license, they are satisfied with merely confiscating your equipment.

[lexicalscope]

I've seen some of the enforcement actions - on a first offense they often just give you a stern warning unless it's clear you were doing it willfully and maliciously (interfering with a company's communications because you have a bone to pick, for instance).

Amusingly, there's been a few cases local law enforcement has asked the ham community to RDF people using their frequencies - at least here most law enforcement uses APCO-25 without encryption, so is easy to monitor and mess with by and large - because it's easier than having FCC get involved.

My favorite mistaken transmission was when a friend noted spurs coming off the strategic command in Omaha that were ending up on ham frequencies. We reported it, an hour later all their spurs were gone.

In any event - yes - monitor mode stuff they won't be able to detect unless they see your equipment, but most equipment is required to restrict the cell frequencies in such a way it's not easy to modify to detect. Most other equipment you have a jumper to enable "everything but cell" TX/RX (Looking at you Yaesu VX-9).

[gpvos]

RDF = Radio Direction Finder

[Buge]

What harm does listening on a frequency cause? If radio waves travel through my house I'm not allowed to listen to them?

[Sanddancer]

That rule was put in place in the early, analog, days of cell phone usage to help build confidence that J Random Somebody wasn't listening to your calls. Cordless phones at the time were well known for being easy to listen to, and the wireless industry didn't want that stigma on cell phones.

[threeseed]

What harm does spying on my neighbour through her window cause ?

If light travels through my telescope into my house I'm not allowed to watch it ?

Seriously just because something is "in your house" does not mean you some inherent right to it.

[Tinyyy]

I'm not in the US and I don't know much about US laws, so can you enlighten me on the relevant laws regarding this? Would it be illegal to stick a 4k camera on your window sill? What about for surveillance purposes?

[BHSPitMonkey]

I doubt the possibility of detection is very high if you're only receiving.

[lexicalscope]

Agreed - they're more concerned about transmission, which is part of why they have more strict requirements around scanners to try a lot harder to avoid this.