After digging several thousand coins with the CTX I find that there are several bits of information the machine gives that help to make a 'dig' decision. As I concentrate almost exclusively on coins, have the nickel area with a high tone, and rarely dig anything other, I use 3 or 4 clues. First as almost everyone will say, hear the tone, second a repeatable target, third where is the target displayed on the scope, what color, size, and depth. I use the numbers almost exclusively on a pin point! I hunt almost all the time in a slightly modified "Gone Hunting program' with the nickel set for a high tone, small coil, manual sensitivity as high as I can stand, and very slow sweep speeds. A left to right sweep will take me about 5 or 6 seconds as I firmly believe the machine is so darned fast with the processing that if I speed it up a bit, say to 2 or 3 seconds across, then a deep coin will just make a tiny, very very quick 'peep'! And if there is a ton of nails and iron there causing the 'splat and grunt' sounds, the good signal is missed by me. So I go really slow.
Quite often I get tones that aren't quite the pure high tone that silver dimes or quarters give and there will be the blue iron target smear on the bottom of the scope. To me great tones sort of start down low and roll up to a high then roll back down. Tones that come in with a bang, sort of a splat with sort of a hazy sound, then it is almost always rusty iron. I can almost always get the tone to repeat, even on iron and from several directions, but the trick there is to pin point it and almost every time the pin point is going to move the actual target over about 4 to 6 inches. The size will probably go up larger also. I believe this is often caused by the high number on the sensitivity, but it also allows me to pick stuff out from iron at deeper depths. I really have almost zero faith in Auto sensitivity to pick out the deeper stuff!
Well, enough rambling.
