Ultrasound Networking (2014) (anfractuosity.com)

That's pretty old news. These days ultrasound mics and speakers can act almost like lowres webcams.

It is more a demo of a full duplex single lonk using twi frequencies (one for each direction), instead of networking. It might be interesting to add a MAC protocol. Interesting work.

> You can see that we transmit in this example at two different frequencies, 19kHz and 18kHz.

Not „just out of hearing range“ for some people. Especially young people can hear up to 20kHz.