Anonymous ID: 85a828 Feb. 1, 2018, 4:26 p.m. No.240426   ๐Ÿ—„๏ธ.is ๐Ÿ”—kun   >>0460 >>0463

>>240408

Very low frequency or VLF is the ITU designation[1] for radio frequencies (RF) in the range of 3 to 30 kilohertz (kHz), corresponding to wavelengths from 100 to 10 kilometres, respectively. The band is also known as the myriametre band or myriametre wave as the wavelengths range from one to ten myriametres (an obsolete metric unit equal to 10 kilometres). Due to its limited bandwidth, audio (voice) transmission is highly impractical in this band, and therefore only low data rate coded signals are used. 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 metres (120 ft) into saltwater, they are used for military communication with submarines.