The purpose of this radiometer is to help characterize both natural and man-made ELF/VLF signals propagating in the Earth-ionosphere waveguide. This receiver operates in the frequency range of 10 Hz to 30 kHz.

Below, ELF radio noise spectrogram shows both lightning sferics (vertical lines) and a quasi- periodic modulation of the 0.5 to 1.4 kHz background hiss.

Tony Fraser-Smith
Stanford University
Phone (650) 723-3684