It looks like it would interoperate with standard amateur radio PSK-31 software if you set the ham radio software to 19043 Hz (instead of more typical 500-2000 or so Hz)
Over the last 15 years or so there have been a lot of PSK-31 software interfaces, so there's probably one that appeals to everyone.
I would imagine other modulation schemes would work in the ultrasound range, if you wanted to try SSTV or RTTY or perhaps a bidirectional error correcting protocol. AX.25 would be amusing and linux has kernel support and softmodem support if you can convince it to run at 20 KHz.
If you've got the bandwidth for Olivia and other modern modes I'd try those... I've made QSOs on HF where there is no discernible signal on the waterfall, works down to very low SNR. So you could get better range / lower error rate with a wider band / slower / more modern modulation method.
I would imagine doppler shift and multipath interference would be an interesting problem.
Do you mean the sound waves would generate radio waves somehow, or are you thinking of the speaker generating EM interference as well? How strong would you expect that to be?
Over the last 15 years or so there have been a lot of PSK-31 software interfaces, so there's probably one that appeals to everyone.
I would imagine other modulation schemes would work in the ultrasound range, if you wanted to try SSTV or RTTY or perhaps a bidirectional error correcting protocol. AX.25 would be amusing and linux has kernel support and softmodem support if you can convince it to run at 20 KHz.
If you've got the bandwidth for Olivia and other modern modes I'd try those... I've made QSOs on HF where there is no discernible signal on the waterfall, works down to very low SNR. So you could get better range / lower error rate with a wider band / slower / more modern modulation method.
I would imagine doppler shift and multipath interference would be an interesting problem.