Garrett Pro Pointer AT (aka "Garrett Carrot") Operating System Type

[ToddB66]

Hi Everyone !

I recently received a reply from Garrett regarding the type of operating system designed for the subject pin pointer.

They said it's a "Static" system, not VLF or PI. That's a new one on me ! Never heard or read of it before.

Can anyone enlighten me on how a static system works, compared to VLF and PI ?

Thanks,

ToddB64

[Davor]

Static can be just about any underlying technology, but signal is processed in a static manner ... which is simply a fancy way of saying the DC component is compensated for, and not removed.
Otherwise it is (most probably) an absorption type detector, with MCU that takes care of detection measurement, DC compensation and response.

Static behaves in a way that at constant distance from a target the device will produce constant response. If you move closer, it will increase whatever it does (say beeping, or pitch), and it will continue doing so. Downside is that DC must be compensated for, and often, as temperature and other effects cause DC drift.

The opposite of static in metal detecting world is motion. It is a fancy way of saying the DC component is removed by means of a high pass filter, or in fancy jargon a differentiator. Its advantage is that you don't have to compensate the DC, but the downside is that you must move to get any response. Say, you move a device near a target, and it gives of increasing response. But once you stop moving, the response wanes.

[ToddB66]

Garrett Pro Pointer AT (aka "Garrett Carrot&quot Operating System Type

Hi Everyone !

I decided to do more research today and came up with the following ad on e-Bay.

Note, Static Operation in the ad below.

"Bounty Hunter Metal Detectors Pin Pointer Hand Held Device Static Operation"

You can copy & paste the above ad title (absent quotation marks) into your search engine window, etc. if you want to see it. BTW, the unit is priced at $44.49.

As asked in my first post "Can anyone enlighten me on how a static system works, compared to VLF and PI ?" Is it superior in some ways ? I would think so since Garrett is using it for the Pro Pointer AT, which seems to be getting very positive reviews ! Nevertheless, I would appreciate your replies to the questions in this paragraph.

Thanks,

ToddB64

[FatBob]

I'd imagine you would want "Static" or nonmotion in a pinpointer so they are just

calling it a fancy name to satisfy your question. All pinpointers should be nonmotion.

It's the same as if they called it DC powered. Ya, so, all are DC powered....

Ask them if they have an "AntiStatic" one!

I used to go into Radio Shack and make up stuff and ask if their computer had it.
They'd usually say yes. Does it have the Quad mux enhancer? Yup it sure does!

[Qiaozhi]

They said it's a "Static" system, not VLF or PI.

Did they actually say "... not VLF, or PI.". or did you add that part?

[kt315]

They said it's a "Static" system
---
thinking majority of p/p's i had seen all are non-motion ie static designed. what new there in the garrett....

[Carl-NC]

"Static" is a mode, not a basis of operation. Technically the Garrett PP is VLF in that it runs at 12kHz, but it's not IB or PI. It's what I call a "loaded-loop oscillator" though I can't recall where I learned that term. Dave Johnson calls it something else, I can't recall that either. Basically it's a high-Q coil in a self-oscillator circuit and when metal gets close, the target eddy currents steal energy from the oscillator and cause the bias to drop. The bias is compared to a reference and the difference drives the VCO audio/vibrator.

This same method was used in the old White's Bullseye and many other pinpointers.

[ToddB66]

Garrett Pro Pointer AT (aka "Garrett Carrot&quot Operating System Type

Static can be just about any underlying technology, but signal is processed in a static manner ... which is simply a fancy way of saying the DC component is compensated for, and not removed.
Otherwise it is (most probably) an absorption type detector, with MCU that takes care of detection measurement, DC compensation and response.

Static behaves in a way that at constant distance from a target the device will produce constant response. If you move closer, it will increase whatever it does (say beeping, or pitch), and it will continue doing so. Downside is that DC must be compensated for, and often, as temperature and other effects cause DC drift.

The opposite of static in metal detecting world is motion. It is a fancy way of saying the DC component is removed by means of a high pass filter, or in fancy jargon a differentiator. Its advantage is that you don't have to compensate the DC, but the downside is that you must move to get any response. Say, you move a device near a target, and it gives of increasing response. But once you stop moving, the response wanes.

Davor, thank you so much !

If you don't mind, I have two questions, as follows:

#1..From your first paragraph, I assume you didn't have the Garrett static system circuit schematic available (from a patent search) in front of you. Without that, I know it's hard to make any conclusive statements. However, I'm trying to decide if a Static system would most likely be superior to VLF overall, (leaving PI out of this discussion). Can you give an opinion on that ?

#2..In addition, regarding your comment "Downside is that DC must be compensated for, and often, as temperature and other effects cause DC drift.", would you guess that (a) the Garrett Pro pointer AT static system has a compensator for DC drift built into the circuit or (b) is the drift problem just something the customer/operator must live with ??

Again, thanks for your help !

ToddB66

[ToddB66]

Garrett Pro Pointer AT (aka "Garrett Carrot&quot Operating System Type

Qiaozhi,

In their email reply they said "is Static (not vlf or pi)".

ToddB66

[ToddB66]

Garrett Pro Pointer AT (aka "Garrett Carrot&quot Operating System Type

"Static" is a mode, not a basis of operation. Technically the Garrett PP is VLF in that it runs at 12kHz, but it's not IB or PI. It's what I call a "loaded-loop oscillator" though I can't recall where I learned that term. Dave Johnson calls it something else, I can't recall that either. Basically it's a high-Q coil in a self-oscillator circuit and when metal gets close, the target eddy currents steal energy from the oscillator and cause the bias to drop. The bias is compared to a reference and the difference drives the VCO audio/vibrator.

This same method was used in the old White's Bullseye and many other pinpointers.

Carl, that's the best answer I've had so far my good man !

Would you be so kind as to take a look at my last reply to Davor and comment on the two questions ?

Thanks for your thorough explanations. (Of course, they are due to your superior knowledge !) I'm serious !

ToddB66

[ToddB66]

Garrett Pro Pointer AT (aka "Garrett Carrot&quot Operating System Type

kt315,

Thanks for your reply. What did you mean by "what new there in the garrett...." at the end of your post ?

ToddB66

[ToddB66]

Garrett Pro Pointer AT (aka "Garrett Carrot&quot Operating System Type

I'd imagine you would want "Static" or nonmotion in a pinpointer so they are just

calling it a fancy name to satisfy your question. All pinpointers should be nonmotion.

It's the same as if they called it DC powered. Ya, so, all are DC powered....

Ask them if they have an "AntiStatic" one!

I used to go into Radio Shack and make up stuff and ask if their computer had it.
They'd usually say yes. Does it have the Quad mux enhancer? Yup it sure does!

Thanks Bob, for the serious part of your reply and the humorous too ! We can always use a good laugh !

Ask them if they have an "AntiStatic" one!

I used to go into Radio Shack and make up stuff and ask if their computer had it.
They'd usually say yes. Does it have the Quad mux enhancer? Yup it sure does! .......LOL

ToddB66

[Skippy]

When you ask "I'm trying to decide if a Static system would most likely be superior to VLF overall" what do you mean? Overall for a pinpointer, or for a metal detector??
It's good for a pinpointer because:
* The target signal doesn't drop away so quickly with distance compared to an IB VLF system, which makes for a greater operating range, and simpler electronics.
*You don't normally want discrimination, so the fact that 'absorption' detection doesn't discriminate is not a disadvantage
*Trying to make an IB coil arrangement in something pinpointer-sized would be troublesome - perhaps a stacked concentric arrangement,like a Sunray Probe may work, I don't know. Winding one simple coil on a fat ferrite rod is pretty straightforwards, in comparison.

Temperature-compensation of these ProPointer-type probes is a tricky one, several things can drift - the ferrite rod itself has characteristics that are temp sensitive, you may be able to measure the rod temp with an IC, etc eg. LM35, AD590, and use the microprocessor to do some math. The oscillator will have capacitors that drift, too. There's lots of options, sometimes you can choose parts so two things drift 'opposite' and cancel, to some extent.
I can't help think a white plastic cased pointer would be better, thermally, especially on sunny days.

[Chet]

Hi Todd
I have been using a Garrett Pro-Pointer for five years. I wore through the heavy plastic tip to the coil. I repaired it with JB Weld epoxy. Drift has never been a problem; it has always been stable on cold and hot days. In mineralized ground I ground balance by placing it against the ground then turning it on. I purchased one of the new Whites TRX pinpointers. I used it for a few weeks and went back to the Garrett. The Whites is a little more sensitive straight in the front of the tip. But it has a blind/null circumference area around the side a little ways back from the tip. For this reason I found that the Garrett was more efficient time wise in finding the targets. The Garrett quickly picks up targets all around the sides of the hole or by just dragging it through the dirt pile.
I hope this helps,
Chet

[Carl-NC]

My replies:

#1..From your first paragraph, I assume you didn't have the Garrett static system circuit schematic available (from a patent search) in front of you. Without that, I know it's hard to make any conclusive statements. However, I'm trying to decide if a Static system would most likely be superior to VLF overall, (leaving PI out of this discussion). Can you give an opinion on that ?

Superior in what way? Simplicity, low cost... yes. Depth, discrimination... no.

#2..In addition, regarding your comment "Downside is that DC must be compensated for, and often, as temperature and other effects cause DC drift.", would you guess that (a) the Garrett Pro pointer AT static system has a compensator for DC drift built into the circuit or (b) is the drift problem just something the customer/operator must live with ??

You can do a pretty good job of temp comp in a metal detector design, which Garrett may or may not have done on the PP. The reality is a pinpointer is typically turned on in short bursts and anything shy of a major temp shift isn't going to be noticed.