This is actually very good - I will try to see what happens when I hear them - but as Petra says - chances are you might be at work or outside or watching tv or..... then sometimes go 5 seconds to 30 seconds... it might be easiest to do the jump off the ground part - would say standing on a chair work? I can see it now at work.... - I wonder if having a cookie sheet and steel pot by your desk would get anyone upset with you?

I like the audio tone generator idea - at least you can match frequencies rather than high,low, medium.

Any ideas on how to set up a ULF detector without a 1000 ft antenna?

Canie