Mike, replies to what you're saying:
"No, no notching. I am referring to visual discrimination....."
Huh ? I think this is just semantics. Ok, call it "visual discrimination" if you like. But ask yourself: What is your goal ? To NOTCH out something that perhaps you're going to do the Las Vegas odds of skipping. Hence "notching" something out. The means to which you do it, and what you call it, are called different things. But the end result of the md'r is the same : To ID and possibly pass junk-of-a-recurring nature. Ie.: round and square tabs which are, yes: pretty consistently shaped . Assuming not bent up, assuming the most common size and soda brands, etc....
"....Well, the V3 can show you this variance in graph form. Normalized, the high frequency hits on tabs hard and you often get a good strong single bar or even a couple of bars but they are side by side, no missing numbers. But the middle frequency allows more discrimination and you see that normal TID variation in graph form. You see the strong 33, 34 and 36 numbers as high and strong signagraph bars and you'll see the missing 35 number. That clues you in to the characteristics of the target. Modern round and square tabs exhibit that characteristic. Normally rings will not show this variation..... "
I grant you that machines like the V3 and XLT, Explorer, etc.... have come a LONG ways in adding more TID info to the items. In the old days (6000 di pro, the early Tek's, the Eagle, etc...) it was just a needle or one-dimensional scale. Yet now we have 2 axis, graphs, etc... They are still all using conductivity as their item being measured. But yes: Some are more expansive than others. And I have no doubt that you can tell the same brand of soda tab (assuming not chopped or bent) with nearly 100% accuracy. And I grant you that the odds of a gold ring having that *exact same* TID signature is slim (but not impossible).
But this is still all defined as notching. Instead of commanding the machine to "go silent" on objects you don't want, you are simply using your eyes looking at the graph. Same exact outcome, if/when you elect to pass or dig certain objects.
" ....On foil range targets, the low frequency performs a mass check for you. Light foil will hit hard at both high and middle range frequencies but will smear the low frequency signagraph with small intensity bars. As the aluminum mass increases the low frequency bars start to condense into less smearing, but as that happens the TID variances in the middle frequency start coming into play and start describing the electrical properties.
The V3 spectragraph is wonderful. I used to turn multigraph off and just focus on the single signagraph response but I've learned that the spectragraph is the better tool..... "
Ok, but what does this have to do with ID'ing gold rings versus aluminum ? Are you saying that you can differentiate foil wads (and/or can shrapnel) versus gold rings too ?