Spectrograms of all 3 axes as the instrument is picked up, rotated, and put back down. The experiment was performed indoors in Montpelier, Vermont, yet the 24 kHz Cutler, Maine VLF signal is clear. (link to image)Power spectrum and spectrogram of a short time segment, showing the VLF signals rising well above the broadband background noise. The experiment was performed indoors in Montpelier, Vermont, yet the 24 kHz Cutler, Maine VLF signal is clear. (link to image)
