I am on the begining of a metal detection project based on the PI technology. The reason is that I would like to find large objects in long depth without care about the metal type (that's why I don't want to use the VLF or BFO technology). The "must" is that the detector may be able to find objects burried about 1-3 meters from the ground. I know little things about antennas and high power analog electronics using burst pulses that the metal detection need. How could I start? Is there any analog circuits I could based on, and building the digital circuit using an AVR and some other like display, buzzer, keys PC interface, battery charger e.t.c.