Re: How to convert voice recording into ultrasound and how to play it?
This reminds me of a friend of mine... Some years ago he was an active member of a students radio club asociated with the tech university in Trondheim, Norway. I'm not into that kind of geekdom, so I don't remember all the details, but at that time a new VERY long wave frequency band was opened for amateur radio hobyists, and his radio club decided to push the envelope a bit...
Acording to legend they rolled theyr own ~1H coils of isolated wire around a pair of plastic barrels, strung an antenna string across the river and then went hunting for a suitable amplifier. My friend hadde just bought a fancy hifi-amp capable (on paper!) of 100w or so pr channel up to ~100KHz. In to the testlab it went, signal generator hooked up and a crowd of geeks staring at the osciloscope while the frequency was cranked up.
Turned out it didn't do much meaningfull amplification above 30K or so, thus my friend took it back to the hifi-dealer and complained about malfunctioning product. The dealer, having some decades worth of experience with young tech students, asked wether my friend realy wanted to HEAR those ultra sound vibes or if PERHAPS there was something else going on here...
After some back and forth he let the students borrow a VERY expensive hifi-amp that WAS indead linear above 100K. And the next day some guy in Japan or Korea refused to believe that the monster strong signal from the guys he chatted with on the "new" band did indeed come from Norway...
This reminds me of a friend of mine... Some years ago he was an active member of a students radio club asociated with the tech university in Trondheim, Norway. I'm not into that kind of geekdom, so I don't remember all the details, but at that time a new VERY long wave frequency band was opened for amateur radio hobyists, and his radio club decided to push the envelope a bit...
Acording to legend they rolled theyr own ~1H coils of isolated wire around a pair of plastic barrels, strung an antenna string across the river and then went hunting for a suitable amplifier. My friend hadde just bought a fancy hifi-amp capable (on paper!) of 100w or so pr channel up to ~100KHz. In to the testlab it went, signal generator hooked up and a crowd of geeks staring at the osciloscope while the frequency was cranked up.
Turned out it didn't do much meaningfull amplification above 30K or so, thus my friend took it back to the hifi-dealer and complained about malfunctioning product. The dealer, having some decades worth of experience with young tech students, asked wether my friend realy wanted to HEAR those ultra sound vibes or if PERHAPS there was something else going on here...
After some back and forth he let the students borrow a VERY expensive hifi-amp that WAS indead linear above 100K. And the next day some guy in Japan or Korea refused to believe that the monster strong signal from the guys he chatted with on the "new" band did indeed come from Norway...
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