"Worked quite well for about 1kb-5kb or so"
That's pretty good. In mud pulse telemetry, used in the oil industry to transmit data from the bottom of the well to the platform, they get much lower data rates. Admittedly over a greater distance and a rather challenging environment.
https://en.wikipedia.org/wiki/Measurement_while_drilling#Mud-pulse_telemetry
Biting the hand that feeds IT
