One Digit or Two - The Perils of VDI
Sorry for my long absence...cancer, diabetes and the other several diseases I have were getting out of hand again, reducing my will to do much of anything at all. But here I am again! Anyway, I was thinking about something the other day; mostly it concerned Visual Display Indicators (or VDI) on today's advanced metal detector screens and I had an epiphany! Between my wife and I, we use about seven different models and makes of metal detectors that utilize a VDI display, all except one machine, which is up on blocks right now awaiting a cable refit, which would be my Minelab Excalibur.
And of the six machines in use, only one machine, my multi-frequency Minelab E-Trac utilizes 28 different frequencies all scanning simultaneously from the single DD coil of choice. The five remaining detectors all use a single frequency, scanning from a single coil. The advance features of the newer machines are impressive, but they also sport what I would term a single two-digit readout on the VDI which means different things on different makes and models, of course. But, despite all the new features in the new machines, my older tech E-Trac is more accurate with it's multi-frequency ability and dual four-digit readout. The four digit readout consists of a ferrous two-digit readout, next to a conductivity two-digit readout. This creates a "matrix" where you can very accurately determine what the probable target is, what type of metal and how big it may be as a target.
The other detectors, with their single two-digit readout, are also pretty accurate to a point, and provide you with a pretty clear dig/don't dig decision, but still with an aura of mystery for those "in-between" numbers that may or not be something good and you decide arbitrarily on whether you should burn the time and energy to recover it.
The strange thing I have noticed, being absolutely honest in looking at my treasure hunting habits, is that using the more accurate system the E-Trac provides, I end up making a lot more "don't dig" decisions. Of course, if you are "cherry-picking" a site, who cares? But, after using some of the more advance single readout machines, target VDI's are not quite so cut and dry. Of course who wouldn't dig a 79 or an 80 on any single readout machine as long as it is not as big as a car hood?
So my habit now seems to be I dig a lot more "iffy" signals on the single-frequency machines, and seem to be rewarded more frequently by interesting finds I would have ruled a "don't dig" scenario with the multi-frequency, multi-readout machine. Of course it is because of my habit's not because of the detector capabilities. So I have gravitated into a new realm where I use the E-Trac for hunting deep old coins and beach hunting, and the single frequency detectors for artifact and relic hunting. Of course that could change any time a new epiphany shows up, but for now, it works for me
Good post Jim. I prefer however the time when ID was your ear and the difference maker.
ReplyDeleteDick, I think, despite the VDI instrumentation on today's metal detectors, your ear is still the difference marker if you really get to know the machine you are using in the field. I know many of my very successful metal detecting friends hunt by the audio signature and NOT by the VDI. The VDI can be very deceptive for a number of reasons. I recently changed the tonal structure of the E-Trac to it's lowest setting, on the advice of an Minelab user from England. He mentioned that you don't get the full tonal range if the initial tone is not a it's lowest setting. He was right and that opened up better audio recognition on my machine! Cheers, Dick and thanks for the comment!
DeleteI do the same thing with my e-trac. It’s easy to cherry pick, but I’m sure I miss stuff all the time. This is a great post. I’d like to repost if I can figure out how.
ReplyDelete