Ground Penetrating Gadget
I would like to find how to build a ground penetrating gadget. I think there are a lot of 'us' would like to have something that can 'peek' underneath the surface of the ground, not necessary very deep. For example, such a gadget that can help fossil hunting tremandously. And it does NOT have to go all the way to Ground Penetrating Radar. As long as it can detect the differences between the matrix and interested object up to say 50 cm in depth, it will be good enough. And it doesn't matter what physical principle is used: GPR, ultrasound, electrical resistance or capacitance, ... (whatever).
What I have in mind in such gadget would be tied to one of the shoes (so, it must be very light weight), using wifi to transmit the signal to iPad/iPhone so that the user can just walk and know the place to dig.
Any help or comment will be greatly appreciated.