Written by the TreasureGuide for the exclusive use of the Treasure Beaches Report.
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| Source: nhc.noaa.gov. |
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Things are often more complicated than you might think. As I suggested yesterday, a number of variables affect the detectors response, and I often can not get down into all the small details in a blog post. Today, however, I will get into some of the factors that can affect your signal and conductivity readings when a junk and good target is involved.
If you tried to replicate the experiment I posted yesterday and got different results, I'll explain today some of the things that could cause that. I'll be using a smaller junk target too. Small things can also produce significant masking.
Here is an example. A clad dime was place about three inches from a husky nail (shown below).
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| Nail and Clad Coin About Three Inches Apart. |
Using the Equinox 600 in factory default settings but with the iron signal turned on, when sweeping the coil left to right and back, the coin was masked when the objects were under the front third of the coil. However, when the objects were under the center of the coil, you could get some coin signals. In fact, you could get a signal that indicated the presence of a good target when the coin was moved within an inch of the nail. When the objects were that close, though, the conductivity readings were less accurate, but it was possible to detect the good target despite the inconsistency in the signal and readings. The position of the objects under the coil was important.
When I approached the objects from a different direction, so that you were swinging in the same direction as the length of the nail, the results were different.
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| Same Nail and Dime Same Distance Apart. |
When I approached the objects from this direction, sweeping left to right and back, the masking effect was much greater. It seems an elongated object tends to produce a larger masking effect when the sweep direction is along the length of the object.
When the center of the coil is over the nail, the coin is masked. When the center of the coil passes between the two objects, you will tend to get inconsistent messy signals and readings.
When the center of the coil is over the dime, but the front of the coil is over the nail, you'll get fairly good signals and readings, but totally consistent or clear cut.
When the coil was moved back so the front edge of the coil was not longer over the nail, there was no masking. I do believe, however, larger objects, such as those shown the past couple of days, you could et interference from the larger objects even when no part of the coil passes directly over the junk object. I should check that out again.
The position of the objects under the coil is an important factor. So is the orientation of the objects under the coil. And, of course, the size and material of the objects are important determinants.
Another factor is the distance between the coil and the objects. In my simple experiments, the junk and good target were at the same level. If the good target was deeper, as might often be the case, the signal from the good target would probably be weaker and the signals and readings less clear.
Which of the below do you think would produce the most masking? Using the Equinox 6oo, in multi-frequency and Field 1 mode, I repeatedly swept from the left to right and back over both the coin and nail on each sweep.
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| Two Photos Of The Same Nail and Dime. |
The nail positioned as shown in the first of these two photos more effectively masked the dime. I don't want to get into too much detail now, but there were a lot of factors that influenced the signals and the conductivity readings.
The important thing to know is that even a small item such as a nail can produce significant masking. Also be aware that a variety of small changes can affect the signal and conductivity readings. Even changing the angle of the sweep by 20 degrees changed the detectors response in some situations, most markedly when the direction of the sweep took the center of the coil over the head or point of the nail.
I recommend investigating masking with own detector and the settings you most use. As I said, there are many factors that can affect the results.
Larry (aka Pavo) did some experimenting of his own. Here is what he found.
using a nox 600, 6" coil, in FE 3 (i think that's equivalent to fe6 on the 800; i think you can get up to 9?? maybe on the 800? I could go look, but i'm lazy); sweep is 3, which is 6 on the 800. I tried it with and without auto tracking, didn't make a difference far as i could tell. Tested in all the 600's modes
Thanks Larry.
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On the Treasure Coast we still have a calm surf and summer conditions. I should get out there. Intend to soon.
Happy hunting,
TreasureGuide@comcast.net