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 acfs@star.stanford.edu