- Super low frequency
radioservices Seafarer (USA) on 76 hertz and ZEVS( Russia) on 82 hertz operate in this range, which is often incorrectly called Extremely Low Frequency(ELF). They both provide communication services for submarines at a certain depth.
sound cards are increasingly being used instead of radio receivers for this frequency range, because of their much smaller size and lower cost. Signals received by the sound card with a coil or a wire antenna are analysed by a software Fast Fourier Transform algorithmand converted into audible sound. [ cite web | url=http://www.vlf.it/ | title=Radio waves below 22 kHz ]
Communication with submarines
* Tomislav Stimac, " [http://www.vlf.it/frequency/bands.html Definition of frequency bands (VLF, ELF... etc.)] ". IK1QFK Home Page (vlf.it).
* [http://spaceweather.com/glossary/inspire.html NASA live streaming ELF -> VLF Receiver]
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