That's an interesting one. Maybe complicating instructions might take too long to encode, but making it a simple buy/sell trigger for one particular security could work? But also going over too long a distance means the stock markets are closed in that part of the world.
There is also a satellite company LeoSat that was trying to build a low latency long distance network of low flying satellites with laser links between them. Guessing that's a "tad" :-) (few billion) more expensive than a pair of shortwave transceivers. But if money is not an issue they say they can do 1.5x faster than terrestrial speed:
Those are microwave which basically need line of sight? I was thinking of lower frequencies which can sometimes go hundreds of kilometers without repeaters.
The lower you go in frequency, the less bandwidth is available.
The entire "HF" spectrum is ~30 MHz. My Wi-Fi at home uses a wider channel than that.
The lower frequencies -- that will travel across the ocean, unaided -- don't have anywhere near the bandwidth necessary (to support the throughput that they need).
PSK31 is 31 bps, but that's with ~100 Hz between channels. DXing is common in the 14 MHz band, so you could probably get to the megabits-per-second range before Physics (or the FCC) stops you.
There is also a satellite company LeoSat that was trying to build a low latency long distance network of low flying satellites with laser links between them. Guessing that's a "tad" :-) (few billion) more expensive than a pair of shortwave transceivers. But if money is not an issue they say they can do 1.5x faster than terrestrial speed:
http://leosat.com/media/1115/leosat-finance.pdf
100ms NY to Tokyo, for example. Not bad.