NICE JOB! Yep, it ain't just about Iron Masking ON IMO helping to pull non-ferrous targets out of iron, it's also about this machine *sometimes* seeming to not average non-ferrous targets seen as "one" to something between them on the scale, or at least not as often in my tests with it compared to my other machines. I've masked coins with tabs and still got a 180 number. Not always of course, but I've also seen it drop only 2 or 3 digits and read like a zinc (which means still a digable target).
Of course it ain't always the case, and you will have a coin and say a tab average it to say like 158 if the tab was say 150 and the coin was 180, but I'm saying that I've seen that 180 or say a 173 or 176 # more often than not when I've played with masking like that. Another reason to not pass up zincs, because it could be a silver that is getting pulled down in VDI by some other target mixed with it in the hole. It seems it's taking the higher conductor and trying to bias the signal towards that end of the scale instead of just averaging the signal somewhere in between like I've seen more comonly on my other machines when testing that. Again, it's not an every time deal. Just saying it seems to happen more with my GT.
I'm sure that largely depends on how big each target is though. A bigger piece of aluminum at the same depth/overlapping a coin so they can both be seen in the field at the same time and I'm sure it'll pull the conductivity more towards the aluminum. Then again, it's the sum of the two sometimes maybe, so maybe it still tries to add up to 180? That's one to ponder for a while and I think I'll do some testing on that and maybe post a video.
It's possible for the field to see two targets in the field at the same time if they are at the same depth and probably have to be overlapping a bit. When that happens the field can wash over both, and then become "one" because that's how the field sees it. If you read Minelab's tech articles though it appears ferrous parts of a signal (such as a nail at the same depth/right up against a coin washed in the field at the same time) can be recognized and the non-ferrous part of the signal pulled out of it. That has to be possible otherwise why would the FBS machines be able to attempt to assign a ferrous and non-ferrous # to a target? That's what I think Iron Mask ON on the Sovereign is doing, but instead of trying to assign a ferrous # to the signal traits it's simply trying to ignore the ferrous part of the signal and sound off to any non-ferrous qualities if it finds any in the signal?
My latest Youtube video on tab/coin masking that I just posted goes more into this topic.