CTX Coil Location When Pinpoint Enabled Makes a Difference

[bklein]

I have found pinpoint to be a pain with the CTX and decided to look into it a bit.
I sat a quarter down on the street and tried some things. My pinpoint lock is enabled so I can use the trigger button to start/stop pinpoint. Sizing is enabled. Detector is in Beach mode.
1. Normal mode sweep left to right, set coil down, enable pinpoint, sweep right to left. I get a constant tone. No sensitivity to the target unless right on it.
2. Normal mode sweep right to left, set coil down, enable pinpoint, sweep left to right. I don't get a constant tone. It detects the target but with not the greatest height.
3. Normal mode. Lift coil up 45 degree angle to sky and enable pinpoint. Ahhhh nice. No constant tone and good detection height.

So I guess the key is to enable pinpoint with the coil up off the ground. Moving just off to either side of the target won't be reliable. I did not see a discussion on this in the manual or Sabisch book but maybe missed it.

Another thing I tried was enabling pinpoint when coil pointed at my car - signal overload - it would not enable. I suspect if your coil is on top of your target and you enable pinpoint it won't be reliable either.
[video]https://youtu.be/bdMOuYPk3Ho[/video]

 

[sube]

This is the same problem I have when I engage pinpoint sizing . You can see in my video where it locks in constant tone I have had this happen in the field you can hold pinpoint sizing in and go 10 feet from the target and still get a constant tone till you let go .

Still don't know where to engage the pinpoint.

Sometimes it works sometimes it don't .

As for engaging it in the air it seems to be more reliable so I assume that it's tuning to the ground when you engage it .sube

 

[bklein]

Yeah, this seems worthy of either a firmware fix or an explanation from Minelab.

 

[Jason in Enid]

I have noticed the same thing, but I believe its cause by metal items being within the coil field at the time you hit pinpoint.

 

[foggynotion]

I get the continuous tone when pinpointing so often that I have pretty much quit using it and just do the wiggle in detect mode, using the rear of the coil to pinpoint. Happy to hear that it's not just me having the problem. Now I know it's not a defect or something I am doing wrong.

 

[trojdor]

You need to experiment with coil height to optimize pinpoint function.

The culprit is that it does a ground grab when you enable pinpoint mode, and unlike normal mode, pinpoint IS affected by GB. (As opposed to the 'magic math' that eliminates the effect of GB during normal hunting.)
If you're like most, you don't use GB thus some experimenting is in order to find the proper height.
(Those of us with bad ground have it the worst...as it's the ground phase shift that's thowing the wrench into the works.)

If it drives you nuts, try this:
1. Enable GB, and balance
2. Now try pinpoint lock at any height.

As if by magic, it shouldn't change threshold at all now. If it does, you didn't GB properly.
(This is how I check to see if GB is 'on the money'.)

As a side note, I've noticed that if I GB properly, as long as I don't change modes, I can then turn GB back off, and pinpoint threshold shift will stay minimal.
Try it.

mike

 

[Digger]

I have found pinpoint to be a pain with the CTX and decided to look into it a bit.
I sat a quarter down on the street and tried some things. My pinpoint lock is enabled so I can use the trigger button to start/stop pinpoint. Sizing is enabled. Detector is in Beach mode.
1. Normal mode sweep left to right, set coil down, enable pinpoint, sweep right to left. I get a constant tone. No sensitivity to the target unless right on it.
2. Normal mode sweep right to left, set coil down, enable pinpoint, sweep left to right. I don't get a constant tone. It detects the target but with not the greatest height.
3. Normal mode. Lift coil up 45 degree angle to sky and enable pinpoint. Ahhhh nice. No constant tone and good detection height.

So I guess the key is to enable pinpoint with the coil up off the ground. Moving just off to either side of the target won't be reliable. I did not see a discussion on this in the manual or Sabisch book but maybe missed it.

Another thing I tried was enabling pinpoint when coil pointed at my car - signal overload - it would not enable. I suspect if your coil is on top of your target and you enable pinpoint it won't be reliable either.

The Pinpoint mode is an all metal, non-motion, modulated audio mode. When you activate the Pinpoint mode, it "ignores" any discrimination Pattern you have set for hunt modes, and switches to all metal. Non-motion means you don't have to continually sweep the coil to trigger a response from a target. And, when PP is set properly, the audio response will increase in volume and pitch as the target nears the detection field of the coil.

As to possible suggestions regarding the results you mentioned...... Placing a quarter on the street and activating Pinpoint with the coil on the street can give you some misleading results. Shallow targets can produce audio responses from the edges and center of the coil. As targets get farther from the coil, the center of the coil becomes the "hot spot". If you are trying to Pinpoint a target laying on the surface for "practice", to get more accurate results, you were wise to raise the coil when activating Pinpoint. This reduced the possibility of a hidden target that would affect the performance of the Pinpoint mode. As pointed out on page 43 in the manual: Do not activate Pinpoint with detector positioned over the centre of the target or the whole target may be masked. Since your target was shallow, I would add that any target within the "reach" of any part of the coil could affect your ability to properly pinpoint. Let me tell you a funny story about a buddy of mine. For whatever reason, he decided to wear steel toed boots on a hunt. He was having a heck of a time retrieving targets and told me that he didn't think his detector was pinpointing properly. I asked him to show me what he was doing and noticed he was pulling the coil toward him when activating Pinpoint mode. As he did, even though the coil was several inches away from his feet, I suspected his steel toe boots were creating a target detection, causing the detector to not recognize the intended target when he swept the coil over it in Pinpoint. To demonstrate my theory, I had him hold his detector up in the air and switch it to Pinpoint. I waved a dime under the coil and it pinpointed just fine. Then I had him hold his pocket knife near the edge of his coil while he activated pinpoint. When I waved that same dime under the coil....there was no target response. One possibility for your circumstances could be that there may have been hidden metal in (or under) the street. When you activated pinpoint with the coil laying on the surface, your CTX could have determined the conditions and would not provide a consistent audio response on the (smaller) target. Remember, when using Sizing Pinpoint, the closer you hold the coil to a target, any target, when activating Pinpoint, the "narrower" the target signal will be. If the detection field picked up on something that it sensed as a target when you activated the pinpoint, even highly mineralized ground, you may not be able to hear an audio response when you sweep back over the intended target. By raising the coil, you eliminated the effects of whatever was in (or under) the street, and were able to successfully pinpoint your quarter. Since you didn't mention the amount of discrimination you were using, another possibility could be that you may be Pinpointing (all metal mode) over something that you didn't know was there when you swept the area in hunt mode, due to your discrimination Pattern. JMHO HH Randy

 

[bklein]

I saw that having the coil that close to the quarter gets you the 3 hit signature instead of a single localized one - but enabling the pinpoint off to the side on the street had no issue as it was distant from the target (no detect in normal detect mode).
That was perfectly "legal" and typical.
What was weird - and repeatable is the difference in results whether the coil is swept left to right or right to left over the target after the enable.
That might not happen if swept so always just one target hit instead of the 3 if too close. I didn't look at that in detail to know for sure.
No discrimination set - basically normal open screen. That is how I normally use the detector.
Definitely whatever background signal is there on the enable will affect the detection depth range on pinpoint. Just carrying a big metal scoop nearby will affect it as I was picking that up often in normal detect and I had to really watch it.
That' is why I like using my green plastic shovel most of the time.
Another comment - where I was, in front of my house, there is underground AC (no poles/wires).
Noise cancel only goes so far and I had to drop Sensitivity way down to below 14 or so to successfully stop the EMI in that area (street).
If you are at the beach and running Sensitivity 28-30, which I often am, nearby targets, scoops, etc. could really affect the pinpoint unless you enable in the air away from the stuff.
Especially running in Normal pinpoint could be a problem as I know I re-enabled Normal pinpoint several times over or very near the target in frustration in my beach hunts. Then I saw that Sizing mode was better - but I still had frustrating experiences.