H-field, Todmorden UK, 53.703N 2.072W
The left hand display plots the time domain signal, much as an oscilloscope would in XY mode with the North/South loop feeding Y and the East/West loop feeding X.
On the right is a short-time Fourier transform. Frequency is plotted radially with the center at 600Hz and the outside at 8kHz. Resolution is about 120Hz. Look out for interesting shapes as sferics arrive on frequency-dependent bearings.
An alternative URL for the stream is http://22.214.171.124/rxvlf1.asx.
More details of the spectrum over a wider frequency range can be found at http://abelian.org/vlf/spectrum.shtml.
Further VLF live streams at http://abelian.org/vlf