Dictionary:Very low frequency (VLF)
1. Radio transmission at frequencies of 3 to 30 kHz, used for communication with submerged submarines and for long-range radio positioning. Most VLF transmitters work in the range 15 to 24 kHz. See Figure E-11. 2. An electromagnetic prospecting method which uses such transmissions as plane-wave sources. The VLF receiver measures the tilt of the total field by nulling one of two small orthogonal coils in the plane of the primary field. See also Figure E-7. 3. A radiolocation system such as Omega that used very-low frequency energy.