Super Low Frequency (SLF) is the frequency range between 30 Hertz and 300 Hertz. In this frequency range there are the frequencies of the AC power grids (50 Hertz and 60 Hertz). The radio services Saguine on 76 Hertz and ZEVS on 82 Hertz operate in this range, which is often called incorrectly Extremely Low Frequency (ELF).

Very long wave transmitters on frequencies under 10kHz are the Russian ZEVS on the frequency 82 cycles per second and the American transmitter Sanguine on the frequency 76 cycles per second. They both provide communication services for submarines at depth. Rumors to the effect that there is to be a comparable transmitter in Berlin Tempelhof, named teddybaer, but independent conformation is missing. To the very long wave receipt beside particularly radio receivers laid out for this frequency range increasingly the PC with integrated sound map is used. Signals, which will receive over the sound map with a coil or a wire antenna, are analyzed by a software to the FFT analysis (nearly Fourier Transfomation) and converted again over sound map into audible sound.