Why cant PI units have Visual ID?

[Newfiehunter]

Why can't PI unit's have Visual ID?

I have a question..if PI units are all metal machines...why can't they make these detectors with Visual ID? At least you can see what you are digging even in all metal mode..and have some idea of what you are digging...Just curious...

 

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[Tom_in_CA]

Re: Why can't PI unit's have Visual ID?

newfiehunter, your "visual ID" (even if it is overlapped with an all-metal mode of ANY kind, whether vlf, pi, etc...) would not be "all-metal", since it is "ID". Even if run concurrently with/overlapping an all-metal mode, the ID portion of that signal is disc, not all-metal. So you would get no more disc. depth, than any currently available disc. mode that is out there. Ie.: you can discern iron, and dig everything else (as you say) right now, with any discriminator. Having a back-ground all-metal mode does not increase that disc. depth.

There is no ability to put disc. (or cross-over disc+all-metal) on pulse machines, because of the nature of that beast. The best they can do is the TDI or GS5, which can pass iron if you know what you're doing. But to do so, you will no longer be getting the fabled depths of pulse machines. You will be down to about the depth you can simply get of various coin/relic machines currently on the market. So why not just use a coin/relic machine from the git-go? If you've ever tried the TDI in junky turf, you would know that even with the high verses low conductors, and the quasi-ability to discern iron, it's still no picnic (ie.: real squirrely and extremely sensitive!)

If the day ever comes that a machine can reach pulse depths, and reliably have full-scale TID, iron disc, etc... down to the full length of that depth, is the day we'll all get rich digging silver coins till our arms fall off Until then, cross-over/mixed modes are not the same thing, nor has the science of what makes PI's tick in the first place, allowed it to over-come the problem for use in junkier relic/land/coin sites (IMHO)

 

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[DGDancer]

Re: Why can't PI unit's have Visual ID?

Iron Patch, (post 4182)
I'm adding a bit of two cents to Tom_in_CA's fair opinion on mixed modes.

Yep the GTI sure does. Thing about the GTI's all metal mode is that, as kinda said, its a combination reading.
The target Id from the discriminator puts its two cents on the display for you to evaluate however the All Metal
mode itself is pretty much VCO. Understanding the two helps~ the target ID system still using discrim circuits
in conjunction with GB as a best guess and the processing involved necessarily limits the max depth sensitivity
of that best guess. Same as operation in a discriminate mode~ coins/jewlery whatever. All metal does not
use the discrim circuit, just GB, and provides max sensitivity to all targets in the field of the coil. That can equate
to depth but does not necessarily mean the machien is punching deeper. Mineralization and GB can limit
the depth of both the discrim and all metal circuits to very simular depths with no gains for the operator trying
to punch a little deeper. Smaller targets will resolve better in all metal is about the only truth I've ever found
to be true between the two modes of operation when high minerals or GB are present.
Try prospecting with one and you'll see. I have, AZ and Australia, and its enlightening even in the city.

What Tom_in_CA says in his statement about PI's is so true...... only I give it about 6 feet. LOL

PI's are the ultimate All Metal machien an will go off on every itty bitty bitty bit of junk you can imagine
with all the associated headaches *and backaches* of recovery at extreme depth. Even with a small
coil. If you use one in the city or near power lines/large structures/rail ways.... oh the EMI dance
in your ears will drive you buggy. But you will get depth provided its quite enough *emi* where your
detecting. Of course its always fun to listen to aircraft transponders to...... me and my GP3000
as well as my first SD2100 had alot of fun experimenting. Salt coils are little gems hehh hehh....

I'm kinda interested in the thought experiment of combining a PI with a Tetrahertz sensing system.
There is some fun stuff evolving in the Tetrahertz field developing if anyone follows that kind of stuff.
That and I got to think that combining a depth reading with a PI should be possible considering
the operating principle is not to far off from a radar range type pulse listen principle...... ah the joys
of digital processing.....

 

[U.K. Brian]

Re: Why can't PI unit's have Visual ID?

There's been several P.I.'s with ferrous/non ferrous I.D. by meter and or audio.

Pulse Analyst that ran on a few AA batteries.
The Groundhawk (British, not the later none P.I. U.S. one)
Eric Fosters P.P.D.1

The standard design is a all metal primary search mode (pulse) with a meter providing ferrous discrimination working on the induction balance principle.
The drawback was that the I.B. side of the machines doesn't have the depth of the pulse side though limiting the discrimination level to only reject iron does make the best of the performance available. The VLF Arado 120/120b and 130 also had the problem of the primary search mode being far deeper than the discriminating side of the machine but the way round this was to locate the deep target which would not I.D. on the meter and remove a few inches of soil, drop the coil in the hole (non motion so hole only needed to be coil size) and repeat until the meter responded.

I was able to try a modern Polish version of the above last year. This worked fairly well on land but didn't cope well with wet salt conditions.

There's a whole range of Polish/Bulgarian/German P.I.'s who's primary use is hoard hunting and do have some form of ferrous I.D. by meter but the standard discrimination methods used rejects iron of fist sized or above only which is not to good for your local park. Some also have a built in magnetometer as a belt and braces approach.