i.e. if there's a blanket ban, can you use your radio hidden in your house or can the government easily find out that the user they've noticed on the airwaves is located there and knock down your door?
Sadly, yes. A bunch of SDRs spread over the whole country with precise clocks or a scheme like the one used in ADS-B MLAT reception (that's based on using the internal SDR clocks without requiring precise clocks on the host) is enough to use multilateration to hone in on any kind of signal, even looking up in raw signals in the past.
If I were to guess, I'd assume that even in nominal democracies the secret agencies are already running such monitoring stations so it's probably already the case that, should need be, all communications can be triangulated.
The HF bands are all small enough to be sampled whole with a single cheap RTL-SDR each, a KiwiSDR can sample literally all of them at the same time, only the VHF/UHF bands need more dedicated equipment (e.g. a BladeRF) - all of that is inside the range that hobbyists can easily afford.
"Huff Duff" is WW2 technology.
https://en.wikipedia.org/wiki/High-frequency_direction_findi...
The units used for detecting and locating clandestine transmitters started WW2 as large truck mounted facilities to hand carried units (with antennas) that fit inside suitcase-sized containers.
Modern ham groups engage in transmitter hunting as part of organized events. Bunny hunting and fox hunting are alternate names for such activities.
https://en.wikipedia.org/wiki/Transmitter_hunting
How to do it: https://www.youtube.com/watch?v=PN-c5DQFuhI
Governments use much large automated facilities:
https://en.wikipedia.org/wiki/Circularly_disposed_antenna_ar... https://en.wikipedia.org/wiki/AN/FRD-10
I don’t understand this sentiment. For exchanging information, modem speeds were great. Wikipedia, forums like this one, instant messengers, etc all worked fine
The problem is, websites got wasteful. You're not going to get any modern website - including Wikipedia - to load in anything close to usable waiting times over a modem speed constraints. HN and maybe Old Reddit are an exception but HN is a niche forum and Old Reddit is probably going to get dumped once Reddit manages to port over all features that were only exclusive to Old Reddit for like six years or so. IRC is all but gone, in no small part "thanks" to Freenode going down the drain and Slack/Discord/Teams eating its lunch.
We got basically three different things. First we got APRS, mostly used for position reports (go on aprs.fi for a map). That is pretty nice but unusable for anything more than a SMS worth of things, and you need repeaters and not just internet gateway collectors to actually have something that's resilient.
Next thing is AX25, the technical foundation behind APRS. Yes you can use it to create actual data links, but it's about modem speeds so virtually useless outside of toying around.
And finally there is HamNet but it's line of sight based and not cross routed to the internet, and identically to all things ham radio, encryption is banned by law.
And on top of that, you can expect regulatory agencies to crack down on ham radio fast and hard, should it be used for political dissency motives at scale. It's already against ham practice to talk politics, especially with people in repressive countries - we don't want more countries other than Yemen and North Korea to just blanket ban ham radio.