What uses very low frequency?

Bands of radio waves BandFrequency rangeWavelength rangeExtremely Low Frequency (ELF)<3 kHz>100 kmVery Low Frequency (VLF)3 to 30 kHz10 to 100 kmLow Frequency (LF)30 to 300 kHz1 m to 10 kmMedium Frequency (MF)300 kHz to 3 MHz100 m to 1 kmWhat Are Radio Waves? | Live Science www.livescience.com › 50399-radio-waves

The VLF band is used for a few radio navigation services, government time radio stations (broadcasting time signals to set radio clocks) and for secure military communication . Since VLF waves can penetrate at least 40 meters (131 ft) into saltwater, they are used for military communication with submarines.

Low-frequency noise is common as background noise in urban environments, and as an emission from many artificial sources: road vehicles, aircraft, industrial machinery, artillery and mining explosions, and air movement machinery including wind turbines, compressors, and ventilation or air-conditioning units .