The licence is not a hurdle. HF licencing in Canada is simple. You get the transmitter certified ($500) and then you rent the spectrum licence. Since there i

The licence is not a hurdle. HF licencing in Canada is simple. You get the transmitter certified ($500) and then you rent the spectrum licence. Since there is actually not much demand for HF spectrum it's quite cheap. If you plan to use it domestically it's the same process as like licensing a single 25 kHz VHF channel for a walkie-talkie. And on licensed channel you can encrypt if you want. But putting a useful transmission on air is expensive. Commercial long-distance shortwave transmitters are megawatt-class. That seems to be the biggest barrier. It turns out to be much cheaper and easier to provide an unreliable 10 kHz channel between A and B through almost any other means. That said: it's clear there's an uptick in data transmission on shortwave over the last ~decade or so. Get a broadband SDR receiver and look at the spectrum waterfall. Here's a capture live from an SDR in New Zealand: https://i.imgur.com/NfFBO34.png https://i.imgur.com/NfFBO34.png Between 8250 and 8300 kHz and slightly more faintly centred at 8200, and also at 8150 see the 50 kHz wide spectrum bands of /// rising diagonal lines? That is a 50 kHz wide channel. Which is broadband in the context of HF when voice band is 3 kHz. It's some kind of spread-spectrum chirp modulation. I've seen broadband OFDM on air as well at extremely low baud like 1 baud but presumably many channels and possible frequencies. Throughput depends entirely on the levels of error correction etc. but the Shannon limit for a 50 kHz channel at low noise is like ~200 kbps. Well beyond sending some weather reports and teletype data. Who? Probably military. Spread spectrum techniques are illegal in Canada and the US at least, on HF, for both amateur and commercial users.