Transferring data using ultrasound

Question

Yamaha InfoSound and ShopKick application use technologies that allow to transfer data using ultrasound. That is playing an inaudible signal (>18kHz) that can b

Answer 1

There's nothing special in being ultrasound, the principle is the same as data transmission through a modem, so any digital modulation is -in principle- feasible. You only have a specific frequency band (above 18khz) and some practical requisites (the medium is very unreliable, I guess) that suggest to use a simple-robust scheme with low-bit rate.