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Wireless networking using a router/receiver with a piezoelectric tweeter which emits an ultrasonic tone, along with a super-sensitive high-frequency microphone. To connect to the internet, one simply plugs the USB reciever which listens for the router's tone and then the receiver and router negotiate
a connection the way a dial-up modem does, but at a higher inaudible frequency (possibly with a higher speed/bandwidth).
||You are not going to get a terribly great data rate. I know that data rate has something to do with signal frequency and pressure waves in air just cannot be switched as fast. Also I suspect there would be a problem due to the relatively slow speed of sound as compared to EM radiation.
||It would probably upset a lot of bats and moths too, but all they ever do is cause hurricanes when they flap their wings. Or something.
||Is it really a problem that radio
frequencies are regulated? Unless so, I
don't see the advantage over a regular
wireless router. I'm not sure how
different frequencies propagate, but I'd
guess that your not gonig to have much
luck at more than 100-200kHz, which
means your data rate is (I'm guessing
here) less than 50kbits/second.
||There is another problem, maybe, as
well. The ultrasound will bounce
around so that the receiver gets the
same signal at various times separated
by tens milliseconds. This is surely
going to make life complicated.
||I'm sure mosquitoes would be pissed
off... beating their wings a million times
per minute, or whatever. I just hope it
doesn't attract mosquitoes. 'Tis the
season to be blood-sucked.
||Oh, and it would be too slow. not travel
through walls, and I don't mind the FCC
regulating my airwaves. No matter how
evil we make them look, they still
organize it so that grandma isn't
catching my wireless conversation.
||A coherent beam of ultrasound, perhaps?
||with ultrasound being somewhere above 20.000Hz, you'd get a data rate worse even than the old 56k modems.