Recently, I've been experimenting with my ATP. I run over a weak tone with pro mode but its showing a good range of VDIs. I rescan it using standard coin and get a much richer,louder bell tone. You have to sweep the area real slow and the standard coin seems to narrow the target down. I then switch back to pro-mode and still get a weaker tone but good VDIs. I dig and its just what the ATP told me it was both tone wise and VDI wise. Try it on an open hunt and you maybe surprized at the results. I'm using 5x8,one bar down from max and no iron discrimination. Works for me.