How dial-up modems used sound to talk to each other

TESLA INFORM on Instagram: "In 2015, the New Horizons probe, after a 9-year journey, had to fly through a «100 km wide "keyhole"» near Pluto with a time tolerance of «±150 seconds». Ten days before the encounter, the onboard computer «crashed and entered safe mode». Engineers on Earth had «72 hours» to remotely reboot and reconfigure systems across a 4.5-hour light-speed delay. They succeeded. Flyby data was transmitted at «2000 bits per second» — slower than a dial-up modem. The entire dataset