Very low frequency or VLF refers to radio frequencies (RF) in the range of 3 kHz to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals are used, such as for radio navigation. Also known as the myriameter band or myriameter wave as the wavelengths range from ten to one myriameters (an obsolete metric unit equal to 10 kilometers).
VLF waves can penetrate water to a depth of roughly 10 to 40 ...
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Very low frequency or VLF refers to radio frequencies (RF) in the range of 3 kHz to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals are used, such as for radio navigation. Also known as the myriameter band or myriameter wave as the wavelengths range from ten to one myriameters (an obsolete metric unit equal to 10 kilometers).
VLF waves can penetrate water to a depth of roughly 10 to 40 metres (30 to 130 feet), depending on the frequency employed and the salinity of the water. VLF is used to communicate with submarines near the surface (for example using the transmitter DHO38), while ELF is used for deeply-submerged vessels. VLF is also used for radio navigation beacons (alpha) and time signals (beta).
VLF is also used in electromagnetic geophysical surveys.
Early in the history of radio engineering attempts were made to use radiotelephone using amplitude modulation and single-sideband modulation within the band starting...
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