Note: If you can clearly hear the send script working then your speakers may not be high quality enough to produce sounds in the near ultrasonic range.
Warning: May annoy some animals and humans.
Simple chat program using near ultrasonic frequencies. Works without Wifi or Bluetooth and won't show up in a pcap.
Tags: computers, mad science, security
It probably won't work for metropolitan broadband, but this reminds me of the thing about pointing a IR laser straight up and then modulating it, and pointing cameras at the sky in the vicinity to try to make transceivers out of IR + dust and fog/humidity. Did anyone ever make that?
Apparently they have been, but range is limited. I don't feel like spending $18 at the moment to find out how much a bundle of fiber optic cables extends range.
This reminds me of the IR transceivers a friend had to administer to maintain the network connection between two offices in buildings separated by a 20' alley. They dropped every time it rained, or the sunlight hit one of the windows in the right way, or a pigeon flew across the beam...
I assume the technology has improved in the fifteen-ish years since, but it's probably still a long way from pigeon-proof robustness.
FWIW, a friend says:
Said friend needs to spend more time at shows so that he can hear just as badly as the rest of us. Until then, our ultrasonic communicators will never work, and he is holding up progress.
24kHz? Really? Has he had that tested properly?
Because >20kHz is exceptional for a child. Due to the transfer characteristics of the middle ear, even in a "superhearing" person 24kHz would be highly attenuated.
I suspect he was trying some computer based test with a lousy sample rate converter and/or DAC; there are many sample rate converters out there with surprisingly high amounts of aliasing artifacts.
Good sound reproduction equipment has low pass filters set at 20kHz because nobody can hear that high, and you don't want crap nobody can hear sapping power and/or destroying speakers. Understandably, speakers don't like frequencies higher than they can reproduce.
As another note: If he really CAN hear above 24kHz, I'm sure a bunch of scientists would be interested in hearing from him!
Hell, he might even be able to discriminate 48kHz audio from 96kHz audio... which no person tested has been able to do so far. In which case, there are a lot of scientists and engineers who would be willing to give him a lot of money
Maybe the software can control the fan, HD, or DVD (empty, for higher frequencies) to make the ultrasound.
Fun fact: the old metal slinkies emit ultrasound. Some old TVs also used ultrasound for the remote control. After the TV went off a few times, we figured it out.
my testicles, my mouth, my party.
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