8/23/19 Report - Atlantic Heating Up. Mint Error. Problems With Air Tests and Tests Gardens.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Source: nhc.noaa.gov

An area of low pressure just east of the upper Florida Keys has a 70 percent chance of developing into a tropical cyclone over the next five days, but models disagree on what it means for South Florida this weekend.

The system, which would be named Dorian if it gains tropical storm status, has a 40 percent chance of developing over the next 48 hours.

While heavy rain is expected from the would-be Dorian, National Weather Service meteorologists in Miami said Friday morning that “global weather models are all over the place and not in good agreement with how they handle this disturbance.”

Looks like the Atlantic is becoming more active.  We might actually get improved beach detecting conditions some day.

We're getting a small bump in the surf now. In the next couple of days we might get up to three feet - which still isn't that much.

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If you check your clad finds sometimes you'll find some interesting things.  Here is a 2016 clad quarter.

2016 P Quarter Showing Strike Through.

Here is a closer view of the strike-through.

Strike-Through on 2016 Quarter.

This has been identified as a strike-through, which is when debris is on the planchet when the die hits it to impress the image.

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Conducting an air test or using a test garden is very different from metal detecting in the field.  When you conduct an air test, you start with a known target and do whatever is needed to get the best signal from the metal detector.  That is the opposite of what happens in the field.  In the field, instead of bringing a target to the detector and presenting it in the best way possible, you cover large areas of ground not knowing if there is a target or where in that acreage a target might be hiding.  In that situation, your behavior is very different.  You scan large areas - probably very quickly.  Your sweep pattern, including speed and height and other factors come into play, as well as various sources of noise, ranging from wind, surf, other people, tinnitus, electrical and radio interference, and ground mineralization to junk.  An air test has very little in common with actual metal detecting.  It is, however, a good starting place for learning about your metal detector.

A test garden is in a specific location.  The detector doesn't have to adjust to changing salt mineralization or any kind of changing ground mineralization, not to mention the fact that and you know where the targets are and what they are.  

I can't stress enough the huge effect of having a known target in a specific location, as compared to not knowing if there are any good targets, or where it might be in an expansive area, and not knowing what kind of target it might be if there is one.  To make that even more complex throw in an unknown quantity of randomly scattered junk targets of various types.

One of the early goals of psychologists was to measure the sensitivity of our sensory systems. They found that factors other than the sensitivity of sense receptors influence whether a stimulus is detected or not.  There is no single fixed level below which a person never detects a stimulus and above which a person will always detect it. Other factors are involved.

This approach [signal detection theory] abandons the idea of a threshold. Instead, the theory involves treating detection of the stimulus as a decision-making process, part of which is determined by the nature of the stimulus, by how sensitive a person is to the stimulus, AND by cognitive factors...  when a person is quite uncertain as to whether the stimulus was present, the individual will decide based on what kind of mistake in judgment is worse: to say that no stimulus was present when there actually was one or to say that there was a stimulus when, in reality, there was none.

To sum that up, detection of a signal is not only determined by the sensory system but also affected by decision strategies (cognitive/thought processes).  Sensory thresholds vary depending upon decision strategies and the value of targets and risk of mistakes.  Thresholds are also affected by expectations.  What weight do you put on the possibility of missing a good target versus digging junk?  Are you excited and expecting to find something big or getting worn out and tired of digging junk.  Those kinds of things can affect your focus, attention and perceptions as well as other behaviors.

An example from everyday life illustrates this point. Suppose a person is expecting an important visitor, someone that it would be unfortunate to miss. As time goes on, the person begins to "hear" the visitor and may open the door, only to find that nobody is there. This person is "detecting" a stimulus, or signal, that is not there because it would be worse to miss the person than to check to see if the individual is there, only to find that the visitor has not yet arrived. 

(See https://psychology.jrank.org/pages/585/Signal-Detection-Theory.html for more about that.)

Signal detection theory was developed during World War II when radar was invented.  They wanted to study how operators could detect planes on the radar scope also showing other return (noise).

The effect of knowing where a target is and working backward to see if you can detect it is very different and results in very different results than you would get not knowing if there is any target at all.  In a test bed, that can be somewhat minimized by closing your eyes and truing to detect as if you had no idea where the targets were.

Unfortunately there is no perfect way to compare metal detectors.  They have so many different settings and there are so many variables in how they are used.  A large part of success is determined by how you use the detector rather than its capabilities.    Air tests and test beds definitely have theie place, but the limitations should be recognized too.

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Happy hunting,
TreasureGuide@comcast.net

8/21/19 Report - New Salvage Finds Down South. Coins Found At Eroding Site. Metal Detector Testing and Noise Adjustments. Storm Scene.

Written by the TreasureGuide for the exclusive use of treaurebeachesreport.blogspot.com.

Silver Ewer Spout Find.
Source: https://www.melfisherartifacts.com/

What do you think the object shown above is?  I'll tell you below.

Down south the crews of the Dare and Magruder recently found silver coins musket balls, pottery shards, a barrel hoop, and a possible carpenter's file.  

They also found an ewer spout very much like one shown above.  I know that the single view didn't give you much of a chance of figuring it out.  Multiple views are always helpful.

The spout shown above was found on the Atocha site years ago and is pictured in the melfisherartifacts database.   Entire silver ewers have also been found with the same kind of spout attached so there is no question of what it is.

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I got a few responses on John E's mystery object that I posted yesterday.

Joe D. looks like an aluminum sprinkler repair tool!

And Susan E. Plumber's multi-tool.

Steve M . says That is definitely an automotive battery connection cleaner.  I have seen those in the 70s but could still be in use today.   They cleaned the lead clamp inside and the lead post outside.

I think John will be able to decide which of those it is.

Thanks to all of you for the help.

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An archaeological site being eroded by the sea revealed Roman coins and pottery.

"The main problem is that everything is under a metre of sand and we're wondering if it blew in in the big storm in 1330 - so it looks like it's been buried for a long time and it's superbly preserved."

Archaeologists' initial estimations think the Roman pottery could be from around 200 to 300AD while the fort is thought to be from the Iron Age, which dates from around 800BC to 43AD.

"That's not to say Romans occupied the site but perhaps a tribe lived there that traded with the Romans," said Dan Amor, of the Gwynedd Archaeological Trust...

Here is the link for more about that.
https://www.bbc.com/news/uk-wales-49397328

1. Luke 3:5 ⁵Every valley shall be filled in, every mountain and hill made low...

--- Yesterday I described some air tests I did. It seems I can't do that without repeating the limitations of an air test, and the importance of not making too much out of the results. You have to start somewhere, and an air test is a convenient starting place when you are just starting to become familiar with a metal detector.  You can form some initial theories to be tested more effectively at a later time, but an air test will not tell you what you will get in the field with real targets. An air test is an OK starting place, but that is about it. If you want to compare metal detectors, the best way is to take those detectors out to the area you want to detect and compare signals on UNDUG targets. Don't dig the targets until after you have thoroughly explored the signals and all of the adjustments you might be interested in. It is important that the targets remain undisturbed in the naturally settled sand or earth to get a good test. If you are interested in the wet sand area, compare the performance of your detectors there. If you are interested in submerged areas, test there. Or dry sand, test there. Test in the same type of area you want to detect. Testing in dry sand for detecting in wet sand will give you very misleading results, but it will help you learn a bit about your new detector before venturing into the wet sand. Also, when conducting a test, you should sweep as you would naturally sweep when hunting. Since I conducted the air test in an area with a considerable amount of electrical interference, I wanted to make a few comments about that. The Ace 250 isn't bothered too much by electrical interference (much less than some metal detectors) but when you need to, you can turn down the sensitivity. The Ace 250 does not have other additional options for dealing with that. The Equinox has a frequency check function to find the best frequency for you. Besides that, you have several choices that you can manually select. You can choose multi-frequency or other specific frequencies. I found that both 5kz and 10kz worked well when I needed to adjust. Sometimes multi-frequency works well, but if you are getting a lot of noise, you can easily change frequencies. You can just cycle through the various frequencies and use the one that seems to work well. From my limited experience, I've been impressed by several things about the Equinox. I didn't expect the display to be as clear and easy to read. Also, for the variety of features that are available, the options are easy to understand and use. The human interface was well designed. Eventually I'll get around to testing it in the field on real targets. That is what really counts. ---

Source: nhc.noaa.gov

Way to the north is Tropical Storm Chantal, and on the other side of the Bahamas is another system that could form. I'll keep an eye on that one. Happy hunting, TreasureGuide@comcast.net

8/3/18 Report - Air Tests and Why To Use Them. Large Cent and Foreign Coin Finds.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

ce

Two Large Cents.

In Florida you find a lot of foreign coins.  Here are a couple of British large pennies.  They are the same diameter as a US half dollar.

Two Large Cents.

As you can see, one is dated 1903 and the other, 1967. The 1903 has a heavy dark patina.

The 1903 might be worth a couple dollars since it is not in great condition, and the 1967 just a few cents.

I have found other large cents from the US and Canada.  It seems like it would make a nice start to a collection of large cents.  I like them better than a lot of other coins.

Hollywood Florida always produced a lot of Canadian coins.  The modern Canadian coins are pretty boring, in my opinion.

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Good Uses For Air Tests.

Before I begin with the proper uses, there are some ways that people commonly used air tests that should not be used.  Air tests do not necessarily provide a good measure of a metal detector's field performance, so they should NOT be used to determine the depth a buried object can be detected in the field or to determine which of two detectors will provide the best performance in the field.

Here are some good ways to use air tests.

- To learn the language of the metal detector.  Learn to recognize the different sounds and readings and what they mean.

- To learn how the metal detector responds to a wide variety of types of targets.  Learn to identify changes in the signal and readouts to different types of targets.   The choice of test targets is very important, and there should be a variety of the kinds of targets that are found in the field, including those that the detectorists really wants to find.  Use test targets that are the same or very similar to what you would most like to find and those that are likely to be the biggest obstacle.

- To learn how different modes and settings affect the detector's response to various targets.  For example, at what setting does the detector eliminate bottle caps and at what setting does the detector lose various good targets.  Settings like discrimination and sensitivity should be varied to observe how that affects the signal and readouts to a variety of targets.

To map areas of coil sensitivity.  Identify the area of maximum sensitivity and how much sensitivity decreases as you approach the edges of the coil.  Where under the coil is maximum depth obtained and how quickly does it decrease as you move out from that area.

I highly advise doing a lot of air testing.  Most people run out to the beach or where ever and hope to learn while detecting.  It's my opinion that spending more time learning to understand the metal detector would be time very well spent.

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There is still no storm activity in the Atlantic.  I'll bet that we get some storms before summer is over.

The surf is up a little to around two - three feet.  The wind is coming from the east/southeast.

Happy hunting@comcast.net
TreasureGuide

6/10/17 Report - How and Why To Map The Cone of Sensitivity For a Metal Detector Coil.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Area of Sensitivity Under Metal Detector Coil.

Sometimes I wonder if I am in an alternate universe.  Some of the things I read are so different from my personal experience that I marvel at how different people can reach such different conclusions.

I sometimes read that this or that detector is really good or bad or this or that feature is really good or bad, and it is 180 degrees from what I've found in my own experience.

Personally, I like testing things for myself.  I don't care what someone is says about this detector or that detector when I can test it for myself.

A lot of the time when you read a detector test, the user just took the detector out of the box and is supposedly doing a field test.  They don't do what I would consider the minimal basics before they begin.  They just don't know the detector well enough to give it a fair test.

I'm dumb, but one detector I now use took me a really long to master.  There is no way I could have given it a fair test the first day or week or even month.  

I haven't talked about this much lately, but I recommend that you do a lot of testing with your detector just to get to know it better.

I was just reading where someone hated a particular coil lock.  I have the same detector with the same coil lock and have used it for a couple of years now.  I often marveled at how well the thing works.  It amazed me to see other people complaining about it.

Maybe it is a matter of quality control.  Maybe some of them are better than others, but I don't think that is what is going on for the most part.

The detector is only part of the story.  The operating characteristics of the detectorist is as important as the operating characteristics of the metal detector.  That is something else I've talked about in the past.

To use your detector well, you have to know it well.  Do your air tests, field tests and learn the effect of each of the settings.

One of the things you should know about your detector is how sensitive the coil is to various targets under different parts of the coil.  This differs for different coils.

At the top of this post is a simple illustration showing that the area of sensitivity for some detectors is cone shaped.  You will detect targets much deeper  when the target is under the center of the coil.

That is one problem with air tests.  People usually pass the target under the coil's most sensitive spot, and they do that in a way that gives the best possible response even if that does not match at all how they move the coil in the field.  The results will therefore be misleading and not very relevant to how the detector will actually perform in the field.

My main point today is that you should know the cone of sensitivity for your detector and coil.  There are big and important differences.

You should map the cone of sensitivity for yourself.  This is one way that an air test can give helpful results.

Pass a sample target under the coil at the front edge of the coil to determine how far it can detect the target when it is passed under the edge.

Use the most relevant test target that you can.  I've written a lot about that in the past.

Next pass the target under the coil but an inch or so closer to the center of the coil.  Observe any change in depth. Repeat that multiple times going from the front edge to the back edge of the coil.  Observe the depth at each spot until you have a map of sensitivity like the one shown at the top of the post.

For example, when I mapped the area of sensitivity for a Garrett Ace 150 with the standard coil, I got sharp cone similar to the one shown above.  Targets passed close to the front or back edge of the coil were detected at only a couple of inches, while targets passed under the center of the coil were detected at least twice as far from the coil.

So what is the practical importance of that?  First, if you want to be sure to find all deeper targets, you will have to overlap your sweeps.  You will have less than half the depth when targets are near the front of back edge of the coil.

Depth is not always critical, especially if you are hunting near surface targets, but you should know the shape of your coil's cone of sensitivity so you will know how to use it for different situations.

The above illustration shows the cone of sensitivity and five overlapping passes for a coil having a sharp cone shaped area of sensitivity.

The first pass would hit the first target, but the deeper target would be missed between pass 1 and 2.

The triangles (cones of sensitivity) are slightly different in size.  That is actually realistic.  Things like ground mineralization changes as does the sweep speed, which is not always optimal, and coil height.

The second row illustrates four passes, but they are not overlapping.  Also the coil height is changed, as happens in real life.

Notice how little area is covered by the cone of sensitivity when the coil is high (passes 1 and 2).  A lot of ground and targets are missed..

That is one metal detector.  I also mapped another detector with a different type of coil.  Using the ATX with a 12 inch DD coil, you get a much more rounded cone of sensitivity.  In fact is not cone shaped at all.   That cone of sensitivity (if I continue to call it that) is very blunt and the edge of the coil detects nearly as deeply as the center of the coil.  Obviously that means you do not have to overlap your sweeps as much.

The edge of the coil on the ATX detected deeper than the center of the coil on the Ace., but my main point today is not to compare different detectors.  My point is that no matter what detector and coil you use, you should know the size and shape of the cone of sensitivity.  You can learn about that by mapping the cone of sensitivity with an air test.  All of my previous cautions and stated limitations of air tests apply.

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Finally a day without rain.

There is no tropical activity in the Atlantic now, but you might want to start watching for that.

Here is a link.

http://www.nhc.noaa.gov/?atlc


Happy hunting,
TreasureGuide@comcast.net

7/6/16 Report - How To Conduct More Meaningful Ground And Air Tests With Your Metal Detector. Summer FUN Convention.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Florida United Numismatists, Inc., is hosting the 10th Annual Summer FUN Convention in Orlando Florida, July 7 - 9 2016. The convention will be held at the Orange County Convention Center, 9800 International Drive.

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I was looking for something the other day - don't remember what - and ran into a video showing some fellows testing and comparing metal detectors on a small piece of buried gold.  They did what most people do.  They buried their target and tried the different detectors to see which did the best. Only one detector gave a good strong signal on the target.  Although I saw a few problems with their method of testing, I wanted to focus on one problem that is not usually seen as a problem.  Almost everybody makes the same mistake.

As you know, there are several things that will affect a detector's signal.  The nature of the target is one thing.  Its composition, size, shape and how it is laying will all affect the detector's signal.

Of course the ground will affect the detector's signal.

And the environment, including such things as electrical interference, will affect the signal.

So will the detector's settings.

But one thing that is not often taken into account is the behavior of the detectorists.  If you watch either an air test or a ground test, you'll always see the same behavior.  The target, relative to the coil, is moved rapidly, in very short sweeps, and right over the sweet spot of the coil.  That is not how the coil is moved in actual field use.  As bad as that is, there is yet another problem.  The exact position of the target is known, which is not the case when you are hunting.  That is a more serious problem than you might think.

When scanning ground during a hunt, the coil would usually be move more slowly, and the target would usually not be directly under the sweet spot of the coil.

When conducting either an air test or ground test, if you want to get results that are similar to actual field performance, the exact position of the target should not be visible to the operator.  I've conducted psychology experiments and know something about how the sensory systems work.

There is always some level of noise, and a signal can be interpreted as noise, and noise can be interpreted as a good signal.  When the location of the target is known, any noise that occurs when the coil is over the target will be interpreted as noise, and the threshold for detecting a good signal in noise will be much lower when the operator knows when there should be a signal.

I've done this myself when I was testing a new detector in a noisy environment with a lot of static. Noise when the coil is over the target will often be interpreted as a good signal when it is actually noise.

People do not realize how much the tendency is to interpret noise or a marginal signal as a good signal when you know that the coil is centered over the target and a signal is expected..  You know when there should be a signal and therefore interpret almost anything as a good signal when you are expecting a signal.  Noise created by hitting the ground or grass or any random noise will be interpreted as a good signal when you know that the coil is over the target. That tendency is multiplied by a coil that is being moved in short bursts over the spot.

The stereotypical very short and rapid movement that is inevitably seen during air tests and ground tests when the location of the target is known and centered under the coil, is unlike anything that would normally happen in the field, except after a target has been located and is being pinpointed.

To get more significant and realistic air and ground test results, move the coil relative to the target like it would be moved during a hunt.  Remember, most of the time in the field the target will not be under the sweet spot of the coil.

In addition to moving the coil more realistically, during ground tests the operator should not be able to visually identify the location of the target.  He can close his eyes and start a few steps away, proceeding the same way he would in the field.  You might be surprised by how often the target is missed altogether when that is done.

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Gold and silver prices have been going up for the last few days.

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It looks like we'll be having another week or two of smooth surf on the Treasure Coast.  There is no tropical weather to watch.

Happy hunting,
TreasureGuide@comcast.net

9/14/15 Report - Good Test Garden Ranking Of Several Detectors. Test Garden Benefits and Limitations. Area Sampling.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Treasure Coast Beach This Morning Nearing High Tide.

The surf was a little rougher than I expected this morning.  In the above photo you can see the water hitting at a bit of a northerly angle.

The surf on the beach shown at the top was breaking a little ways out.  That was one of those beaches with a flat front that I was talking about the other day.

You can see the relatively flat beach front where the surge from the breakers is washing in.  That white water area has a pretty good current that runs both way - surge and backwash.

One Beach Showing A Little Scalloping This Morning.

The second photo shows a scalloping beach.  That is one of the more coarse grain beaches with more of a slope.  That beach, unlike the one at the top, was scalloping a little.

We're supposed to get a little change in the weather and the surf on the Treasure Coast will pick up a little but not much.  Expect something like three feet on Wednesday.

Tropical Activity As Of This Morning.
Source: nhc.noo.gov

The tropical disturbance shown in red has an 80% chance of becoming a cyclone in the next 48 hours.  At this time, I think that one is the one that we should most closely watch.

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I ran across a good YouTube video in which the Ace 350 was tested and ranked with a variety of other detectors.  It was an exceptionally good test in an extensive test garden.

The test not only provided a test of the 350, but I think also gave a good general idea of how detectors in general work with various targets at different depths.

At the end of the video the Ace 350 was ranked with a number other detectors that were tested in the same way, providing a good comparison.

You might benefit by taking a look at the video.  Not only were a variety of targets buried at different depths, both good targets and junk, but very small targets, such as a gram of gold, were also tested. Tests were also conducted with coins buried with nails and other junk.

It was one of the more extensive test garden tests that I've seen, and a good informative video.

Here is the link to the video.

https://www.youtube.com/watch?v=fDAvWgalcrA

Of the various detectors tested in this test garden, the Nokta Fors CoRe did the best, achieving 55 out of 66 points, the Ace 350 came in below the middle of the pack with 33 of 66 points, and the Minelab Go Find 60 and Garrett Grand Master Hunter II came in at the bottom of the rankings.  Although it was second from last, the Go Find had 28 out of 66 points, not really very far below the Ace.  You might find the comparisons interesting.

The Nokta normally sells for up around $800 while the Ace more like $350, so you have to take price into account.

In this particular video, it would have been better if you could see the actual screen readouts to each of the targets, but that is asking a lot of a home video.

I do want to remind you that there are significant limitations with all test garden tests.   One problem with test garden tests is the fact that they are conducted in one specific type of ground, which may or may not be like where you will hunt, but more significant is how the detector is used. Detector settings and modes may not always be ideal and may not always be comparable from one detector to another.

Another problem with both air tests and test garden tests is that you know where the target is and can see when the coil is centered over the target.  If the targets were spread out and the tests conducted blind folded, that would be a better test.   Again, that is too much to expect, but it is important to be aware of the problem.

Another problem with air and test garden tests is the detector is not used as it would be in the field.  That is very significant.

During a test, the targets are directly under the hot spot of the coil.  And the coil is repeatedly moved directly over the target until the best signal is achieved.  In the field the sweep speed is seldom ideal and the coil is seldom directly centered over the target.

That may sound like nit-picking but those things are very significant.  Test it yourself.  Throw a behind your back and shut your eyes and detect normally.  I think you'll be surprised by how often you miss it.  If you don't miss it altogether, you might get the target at the edge of the coil or at the end of a sweep and don't get the best possible signal like you would get from an air test or test garden test.

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I saw two other detectorists out this morning.  I detected very little, but did some detecting.  I sampled a few spots and found the most targets where I would have thought that other detectorists would have cleaned things out.  This is a heavily detected beach, but the most obvious area seemed to have the most targets. Surprise, surprise!  Sometimes you guess wrong, and that is why I like to sample various areas.  I like to do a little sampling to prove or disprove my guesses.  I won't necessarily spend much time sampling, but a little bit often helps a lot.

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Happy hunting,
TreasureGuide@comcast.net

5/18/15 Report - What To Do First When You Have A New Detector. Sunken City Discovered by Divers. A Versatile Camera.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Gold Ring Beach Find.

I seldom look at YouTube detecting videos but was bored the other night and had a few minutes to waste.  The first video that I looked at drove me absolutely crazy.

First, the video was made using a detector that had a very annoying signal.  It sounded something like a mosquito or maybe a cheap child's toy meant to drive a parent crazy.  I think detector companies should put more thought into how signals sound.

But the thing that really drove me crazy about the video is that the guy continued to show his meter as it jumped around as he passed the coil over one undug target after another.  It obviously was a very junky area.  I quickly got tired of watching the meter jump around.  I wanted to shout dig the dang thing if you want to see what it is.  He was detecting in a shallow creek that had little soil covering flat bedrock and could have easily exposed most targets in almost no time.

I felt a little better about the fellow when I found out it was the first time that he had used the detector.  I could then understand why he was spending so much time watching the meter, however he would have been much better off doing his first tests in a controlled environment.

If you don't have a clean area of ground you should find an area that you think might be clean, get some test targets and do your first tests there.  And before that you should do some air tests.

I've mentioned before that I wouldn't use an air test to see how deep a detector will detect a particular object in the field.  Detecting in air is different from detecting an object in the ground, but an air test still can be very useful for becoming familiar with a detector, its different settings and different signals.

If you want to learn more about your detector, start in an environment and situation where you can control most factors.  Don't start with a lot of unknowns.

And when you are ready for a field test, start with the simplest situation first and then gradually work into more complex situations.

For example, on a beach, start in the dry sand.  After you've got a handle on that, move to wet sand, and after that, maybe move into shallow water.  Go from simple to more complex.

As you've probably noticed, I do a lot of experimentation with detectors and objects.  I don't put much stock in what other people say.  I rather test something out and prove it for myself.  I guess that is just the kind of person I am.  I spent a lot of my professional career doing research and conducting experiments.

I've found some commonly accepted knowledge about metal detecting to be wrong.  I recently tested a detector coil that was supposed to provide excellent target separation.  It didn't.  You can't always go by the theory of things or what you hear or read.

I highly recommend doing a lot of air tests and tests in a test garden, as well as field tests with any detector, especially when you get a new detector.

The fellow that made the video I was talking about would have been much farther ahead if he had done  his first tests in a test garden rather than a junky creek.  I understand the temptation to run out and and see what you can find with a brand new detector, but for me I'd rather have some idea of how it works and what to expect before I take a new detector out for a field test.  If you just can't hold your britches, at least pick a fairly simple environment like a dry sand beach for your first tests, preferably one that has been pretty much picked clean.

Another thing I want to say is, Dig it! If you want to know what is causing a signal, put it in your hand, hold it and look at it.  When you really know how to use your detector and what it is saying to you without spending five minutes studying at a meter, then you can strategically pass over targets, but until you reach that point you'll learn a lot more by digging.  You'll also avoid some big mistakes.

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Divers discovered the ancient city of Heracleion while searching for Napoleon's ships.  Use this link to read the article and view the video of divers exploring huge stone monuments and statues.

http://www.dailymail.co.uk/sciencetech/article-2336723/Ancient-Egyptian-city-lost-1-200-years-begins-reveal-secrets.html

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I completed testing of one of the newer detectors and expect to have that written up before long.

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As you know I often post various kind of photos in this blog.  I often post pictures of the beach and various finds.  I also once talked about how it is a good idea to take photos of finds for your personal detecting records.  Not only will that help you remember your finds, but photos might also be necessary for insurance purposes.

There is one camera that I've found to be especially reliable and effective in most situations.   It is my Sony Handycam.

You've seen beach pictures that I've taken with that camera.  It also did the best job of taking pictures of flourescent fossil shells under black light.  That wasn't easy, but the Handycam did the job better than any other camera I have.

It has a still photo button, but I more often take a video and then select clips from the video.

Here is a photo that shows the camera's versatility.

Dragon Fly Photo Taken With The Sony Handycam.

Getting this photo could be a challenge with any camera but was easily accomplished with the Handycam.

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On the Treasure Coast we have some very nice weather.  The surf is still around two feet, but we have been having some nice low tides.

No change is expected this week.

Happy hunting,
TreasureGuide@comcast.net

1/20/15 Report - How To Select Good Test Targets And How They Can Be Useful In The Field

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.BlogSpot.com.

Treasure Coast Beach Yesterday Near Low Tide.

Notice all of the new sand on the front beach.   Not looking good.

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I like trying out new detectors.  I like to learn what they can and can not do.  At the same time, I hate using a new detector because I don't know how to use it well.  I guess I have a love/hate relationship with new detectors.

Some detectors take longer to learn than others.  The Ace 350 took very little time to learn.  You can continue to learn to use any detector better for quite a while, but you can become fairly proficient with a detector like that in a relatively short amount of time.  Like I've explained, it is an inexpensive detector and there are detectors that will detect deeper and do a lot of things better, yet it has a place in my arsenal and there are times when I'll use it rather than one of the higher-end detectors that I have.  There are times when it is the best choice for a particular situation even though it is the least expensive.

I've talked a lot about test targets in the past, and I continue to see more and more value in using test targets. It seems I'm always learning.

I am currently learning to use a detector that is new to me, and it hasn't been on the market very long.  Just yesterday I was exploring and comparing the motion and non-motion modes and a variety of other things in a very challenging environment.   I've had it out in the field maybe four or five times now.

I should comment here that when you are learning to use a new detector, you should first do some air testing and some test garden testing in an environment that you are very familiar with.

I have a spot in my yard that I have used for testing for a long time.  I know that spot to be very clean.  The one thing that is not so good about that spot is that there is a good amount of EMI.  That, of course, is not the ideal for a test garden.  It is better to get away from EMI, junk, mineralization, etc. as much as you can for your early learning experiences with a new detector.  Each of those things can complicate the situation.

If you have one place that you have explored many times before with other detectors, you will know something about what to expect and be able to compare the new detector and how it responds with other detectors that you have used there before.

Getting back to test targets.  I was detecting with this new detector in a fairly challenging environment the other day.  I had already spent a few good learning sessions with this detector and was ready to step up the difficulty level.  This beach had a lot of very small pieces of iron, also a lot of very large pieces of buried iron, along with the normal salt mineralization, wet/dry zones and black sand.

Anyhow, at one point I noticed less signal strength than I would have expected from a small piece of foil.  Hmmm.  I took out a small test target that I have used quite a bit.  I know how this detector and other detectors respond to that particular test target under various conditions.  I threw it out on the ground ahead of me and indeed, the signal was not what it should have been or what I would have liked. 

Somewhere along the line the detector was detuned somehow.  I have my suspicions.  I think it had to do with some huge buried iron that I was over or a while, which could have caused the detector to retune.  However it happened, the detector was detuned and my test target quickly confirmed that the detector was performing less than optimally and was out of tune.

That is just one more example of how carrying a test target can help you.  The fact that I had used this test object before and had a good idea of how the detector should respond to it was a big help.

Select a sample of objects that include the types of things that you are interested in finding.  For example, you might include a coin, a small silver object, a small gold object, and perhaps a cob.  Again, select the kinds of things you are most interested in finding.

The most effective test targets will give off a small but distinct signal if the environment is challenging.  Don't use test targets that are too large or too easy to detect. They will give a strong signal even if you are slightly out of tune.  You want targets that produce near borderline signals that will be most affected by changes of the detector settings and changes in the environment.

You can use the same test objects for air tests and in the field.  By using the same test targets over and over, you will learn what type of response to expect from different detectors in different environments.  That will help you compare detectors on the different types of targets in different environments.  It will also help you better evaluate your settings.  Having a well known test target along with me helped me quickly determine that my detector was responding less than optimally, and it also helped me retune the detector to obtain a near optimal response in the environment where I was hunting.



Not much change in Treasure Coast beach conditions to talk about.  Same small surf and sandy beaches.  No change in expected real soon.

Happy hunting,
TreasureGuide@comcast.net

1/19/15 Report - Some Problems With Air Tests: Physical & Psychological. Calm Surf and Sandy Beaches

Written by the Treasureguide for the exclusive use of treasurebeachesreport.BlogSpot.com.

Fresh Cut Found On Treasure Coast Beach Yesterday.

Everybody knows that an air test won't tell you exactly what you can expect in the field.  An air test doesn't have to deal with things like ground mineralization, but in my opinion there are much bigger concerns and limitations.

When you test a detector you are not just dealing with one system.  The detector is an electromechanical system, but when you use a metal detector there is actually a much more complex and important system involved - your nervous system, including your sensory system.

Before I address those systems and how they play a very important roll, I want to talk a little about air tests.  There is the problem of generalizability.  An air test is not like a field.  There will normally be some difference in how far your detector will detect an object in air and how deep it will detect an object buried in the ground.  Most everybody knows that.  But those differences are not due ony to the differences in the ambient environments.  Some differences are due to how air tests are conducted.

I'm sure that most of you have conducted an air test and have watched others conducting air tests.   Carefully observe the human behavior involved. 

Usually a person conducting an air test will start close to the coil where a distinct signal is achieved and move the object farther from the coil until the signal is no longer distinguished.  One problem is that during an air test, the object is usually moved right over the sweet spot of the coil.   Most often that does not happen in the field.   Usually the object will be off one direction or another.  During an air test, people usually seek the sweet spot until they get the absolute best signal.

In the field during a hunt, an object will only fall under the sweet spot a fraction of the time.  In more cases than most people think, the object will not pass under the coil at all.  In the field many objects are missed by inches, and when the coil does pass over them, it is just as likely that the object will be at the edge of the sweep, and only occasionally under the sweet spot.

Secondly, and no less important. the sweep speed is typically varied during an air test until the optimal signal is obtained.  I think that more often than not, people are not using the optimal sweep speed in the field. 

I've mentioned this before, but you should test your sweep speed in the field on a sample target, and then either speed up or slow down your sweep speed.

Thirdly, during air tests, the object is kept in a very narrow area just under the coil.  Most signals may be attributed to the object - not always accurately.

It is more difficult to detect a signal in noise, such as you might get in a field environment.  In an environment with noise, your nervous system will adapt and begin to ignore marginal signals such as those that you would might attribute to the target (correctly or incorrectly) during an air test.

Thirdly, as I stated above, the detector is not the only system involved.  Your nervous system, including your brain and sensory systems are also involved.  Those systems are very important.  They are very flexible and may adapt in ways you don't realize.

Here is one fun example.  Which of the following horizontal lines is the longest?  Don't include the arrow heads.

Maybe you've seen this classic demonstration before.  The three horizontal lines are the same length.  Measure them if you need convincing.

The point is that your nervous system interprets sensory data.  It can be fooled and sometimes it is wrong.

When you do an air test, not only do you listen but you also see when the target is under the coil.  Try this experiment.   Close your eyes and pass the object under the coil.  You might find that you can not distinguish the auditory signal quite as well when you are not also seeing the object under the coil.  That will be even more true if you are in a noisy environment.  Not using the visual information will make the auditory data more difficult to interpret.  During a hunt you will not see the object when you hear the signal, that means that a more distinct auditory signal will be required for it to be correctly interpreted.

Don't get me wrong.  I'm not saying that air tests are no good.  I'm just saying that they can be misleading, and you have to be cautious about drawing too many conclusions. 

I think most people should probably do air tests more often.  They should not, however, attempt to evaluate a detector based upon air tests results, and should be cautious about generalizing from an air.

I hoped that by pointing out some of the problems with air tests, both physical and psychological, you will be able to conduct more meaningful air tests and draw more accurate conclusions.

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We are back down to a one or two foot surf on the Treasure Coast.  Really smooth.   That will make water hunting easy.  Also easy to do the low tide area.

The surf will not be increasing hardly at all for the next few days.

The cut shown above was not visible from any beach access.  You'd have to walk a ways to find it.

Happy hunting,
TreasureGuide@Comcast.net

9/13/14 Report - Problems With Air Tests. How To Test Your Metal Detector. Buried Objects and Disappearing Signals. Tropical Storm Edouard.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.BlogSpot.com.

Source: www.nhc.noaa.gov

Not long ago I said the best way to compare detectors is to take the detectors out in the field and compare them on targets that have not yet been dug and compare the signals.  That gives you a comparison in the specific environment.   I'll explain my ideas on testing detectors today and explain some of the problems with some common approaches.

Everybody knows about air tests.  One of the problems that I have with air tests is that the test targets are often not the best.  People tend to use a clad coin of one denomination or another.  As I've explained before, unless you want to find a clad coin, that is not the most relevant test.   Different detectors react to different types of targets differently, therefore you should use test targets that include the types of things you are most interested in finding.  A single test target won't tell the entire story. 

Some people use a nickel because it has a relatively low conductivity, supposedly something like gold, but however true that might be, few gold items are shaped like nickels.   Most gold targets are not solid disks and few are as thick as a nickel.

One big problem with air tests is that they usually aren't done in the type of environment where you will actually use your detector.  They are often done in a house or yard, where there are power lines, underground cables or other sources of electrical interference.  Some detectors react better than others around sources of electrical interference.  That will affect your air test results.  Most beaches are relatively free of electromagnetic interference.

An air test does give you a little information, but it isn't a very good test for comparing detectors or for figuring out how deeply real targets can be detected in the field.

Another approach is to take the detector out and dig a hole and bury a target and then see how deeply the target can be detected.  Of course, for that test to be most accurate, the target should be buried in the type of ground you intend to hunt.   Some detectors will work better in dry ground, others in wet  salt sand, etc. 

Even if you are in the right type of sand or soil, you will not get an extremely good  measure using a newly dug hole.   A target in a newly dug hole will NOT give the same response as a target that has been buried for a good amount of time.

You've probably heard about the "halo effect."  Supposedly a naturally buried object will have a halo effect and therefore give off a stronger signal than a newly buried target.   I won't get into how the halo effect is supposed to work, or even what it is, but I can say that a newly buried target won't give the same signal as a naturally buried target that has been in the ground a while.

Have you ever dug a hole to get a target in the wet salt sand and you couldn't find the target in your scoop or in the hole?   It seemed to disappear.

Here are some things that could have happened.  The object could have slipped down deeper in the hole, or it could now be sticking to the side of the hole and standing on edge, thus presenting less surface area for the detector to detect.  Those are two ways that a target can seem to disappear in a hole, but there is another.

Go to a beach where there is compact wet salt sand.  Dig a hole.  Now run your detector over the hole.  If you are in all-metals mode, you might well get a signal from the hole where you disturbed the sand. 

If you can find some black sand and run your coil over it, you might get some false signals, but if you dig a hole in the black sand, or even disturb the smooth black sand, you'll probably get a bigger signal from that.

If you don't get a signal from the disturbed sand of a new hole or the black sand, your detector is probably canceling that source of noise out and you'll therefore likely be getting less depth.

The thing is, a newly dug hole will change the ground, either causing false signals or changing your ground balance so that your detector is less sensitive.  That is another way an object can get lost in a hole,  The hole itself disturbs the ground, which can cause false signals or a change how your detector is ground balanced.

Another problem with digging a fresh hole in sand, especially wet sand, is that the entire matrix changes.   Just watch a newly dug wet sand hole.  Water will come in and fill it.  Sand and shells will move about and settle,  And if you threw a coin into that hole, you saw where and how it was before you covered it, if that is what you did, but you won't know how or where it settled after that.

Since a target in a newly dug hole will settle, and since a newly dug hole disturbs the sand and creates false signals or changes the detector's ground balance, I do not find newly buried objects a good way to test a detector on a target.   The sand or soil in a newly dug hole is not settled like the sand or soil surrounding a naturally buried object.  And it may have not had time to create a halo effect. 

To me, setting the object on the ground where you intend to detect, and then raising the coil above the object is just as good, or in my opinion, a better way to go.  That way the detector will be responding to the natural undisturbed ground in that area.   It is true that you won't be detecting "through" that type of ground, but if your settings are right, that won't matter much.   I think you will get as good an estimate of depth by raising the coil over an object on the surface as by digging a hole and disturbing the ground. 

Also,if you experiment a little, you'll see that an object in a very well packed area will generally give off a better signal than the same object buried in course material, such as course shell sand.

 

As you can see there are three areas of weather to watch.  (See map at top of post.) The weather system that has been bringing us wind and rain has now moved into the Gulf.

Edouard is still out in the Atlantic, and there is one more disturbance following Edouard.

On the Treasure Coast we still have a small surf and fairly good tides.


Happy hunting,
TreasureGuide@Comcast.net