I have yet to find a coin on edge that way , not saying it don't happen just that I haven't necessarily seen it. Usually those one way hits are either multiple targets , like a high tone target right next to a discriminated target , or trash that is partially discriminated out. Say you have a coin or other high tone target next to a piece of iron.....if the coin is the first target the coil passes over you can get a high tone from that direction and then the iron is ignored.....but when passing the other way the iron gets disc'd out and before the machine can retune to pick up the coin next to it the coil has passed over it.....target now out of the detection signal. The ATP is has a fast retune time and normally is good at separating targets but if they are positioned just right in the soil you may not get a separation , only a one way hit.
In over 20 years of detecting , and atleast 3 of those years with the ATP , I cant say that Ive ever found a verified coin on edge....though a few appeared that way after I dug and disturbed the soil....its very hard to tell if the coin was on edge before you started digging , they usually get that way as you dig. I wouldn't be surprised if most.....if not all reports of coins detected on edge were actually coins very near iron or clump of minerals in the soil that cancelled out the hit in one direction. Not only is it difficult for a detector to hit on a coin on edge , but the only way to be sure it was on edge would be to leave the soil around it completely undisturbed , packed and intact somehow and the odds of that happening as you are digging it up are not very good. I wont say it cant happen , but try doing it on purpose....I bet you cant.
I will have to stick with the target being trash , a coin right next to trash , rusted away iron , etc.... , or something environmental that causes the one way hits. I have found coins with one way hits but the majority of them that I dig are not.
