VLF radio noise

The Ionospheric Effects Branch of the Space Science Division at the Naval Research Laboratory is engaged in an ongoing program to measure the natural noise environment at VLF. A Navy P-3 aircraft has been used to measure the ambient noise at 35 kHz. There are three orthogonal loop antennas so that both TE and TM components of the noise can be measured. Mean noise levels and values for V sub d will be presented for 1620 observations on seven days in July and August 1986. Examples of the observed APDs are shown. This experiment observed values for V sub d significantly lower than the C.C.I.R. values which probably indicates that these observations were heavily influenced by local noise rather than atmospherics.