VLF signal dataset radiated by NWC transmitter

There are many artificial very low frequency communication stations worldwide, with operating frequencies ranging from 1kHz to 50kHz. The VLF electromagnetic waves emitted by ground based very low frequency artificial sources can be reflected back and forth between the ground and the ionosphere, and propagated to a distance using the Earth ionosphere Waveguide (EIWG).

During the propagation process, some energy can also penetrate upwards into the ionosphere and propagate in the form of right-handed polarized whistler waves towards the top of the ionosphere and the magnetosphere, ultimately being received by satellites. Numerous studies have shown that the main energy attenuation of VLF electromagnetic waves propagating upwards occurs in the low ionosphere region, and after passing through the low ionosphere, their energy almost no longer decays.