Super low frequency
From Biocrawler, the free encyclopedia.
Super Low Frequency (SLF) is the frequency range between 30 hertz and 300 hertz. This frequency range includes the frequencies of AC power grids (50 hertz and 60 hertz).
The radio services Saguine (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 depth. There are rumors that there is to be a comparable transmitter in Berlin Tempelhof, named teddybaer, but confirmation is lacking.
PCs with integrated 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 algorithm and converted into audible sound.
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