that same depth issue

[Anonymous]

i'm still unable to find a coin deeper than 7 inches in the ground. since I got this machine in april, Ive been given good advice, and even had a couple pro's meet up with me to try and help
my settings are
sens 22-32
volume 6
gain 9-10
deep on, fast off
I.M. -16
This I'm told is about as hot as it gets.
I have a coin garden that I planted just after I got my explorer xs. Though there is some iron in the soil, Its not enough to break the threshold. the wheat back pennies in my garden range from 4" deep to 12" deep. starting with the one at 8 inches I get a signal Identicle to rusted iron, not very repeatable and about half the sweeps dont get it at all.
I've tried burrying pennies at the beach and in various other locations such as empty (clean) ballfields and sites with lots of debris. I even burried a coin with general ray (who has found coins deeper than 7 inches) and his explorer 2 couldn't get it.
please keep trying to get me past this!!

 

[Anonymous]

Let me suggest something a little different. I am not sure why but a one cent coin will give odd reading. As an example some Indian heads will read FE iron and just to silver which is far let corner to far right corner. Soem will read in the top one quarter and others will give almost no signal but are just under the soil. They are a sorry coin to test with and most are not worth much other than the Indian Heads. The large cents I have found are so badly damaged that all they are good for is to say look what I found. I don't mean to play that down as bad as I have but why not start with a Silver Quarter.
Using the setting you have but try this. Set the <span style="background-color:#ffff00;">sensitivity to 28 in manual and also try semi-auto.</span> I have a quarter at 8" and hit it with the small coil so hard it knocks my ears off. If you are using the stock coil you should nail it hard. See what that does and we can go from there.
I have not said much in this area but the soil minerals are for the most part completely ignored by the EXS and EX2. This single factors is why we have the Explorer series. The EXS and EX2 are not like a multiple frequency detector in that they are a subgroup of a PI detector. That is they use both time domain and multiple frequency so can discriminate. Ground minerals should never be a problem if you have the IM at -16.
The last time I saw this was when the test garden was in an area where co-located targets were killing the coin. So give this a try if you like. Use the setting you have with sensitivity to 28 and search for targets in the area where you have the test garden. Dig those targets up and see how deep they are. If you find deep iron and other trash then your detector is working properly as far as depth is concerned.
<span style="background-color:#ffff00;">
Be absolutely sure to Noise cancel with each use or when you change the gain or sensitivity.</span>

 

[Anonymous]

Thanks Cody.
Excelent suggestions. Ive used indian heads as well as wheat back pennies and silver dimes, but never a quarter. I always figgured if I could find a dime, a quarter should be no problem, but I hadn't thought of using a quarter instead of a dime. I want to be able to find deep dimes because finding a quarter happens relatively infrequently, but maby I should learn on quarters and then move up to dimes so to speak.
There is definately small bits of iron trash in my garden, and I think I will try to redo it before the ground refreezes. I doubt this is the real problem though, like I said, I've tried clean ground with the same results.
I was using noise cancle regularly, but It doesnt usualy help much, and I can generaly find a quieter channel manually. with occasional exceptions, it seems like a waste of time.
Manual and semi auto sens might be worth experimenting with, Ill give it a try.
I am considering sending the unit back to minelab to be checked out when the ground freezes. I did that with my bounty hunter and they were able to improve it significantly.
Thanks again Cody!

 

[Anonymous]

Are there any really deep coins where you are hunting? Settings vary from area along with multiple ways of setting up so we won't get into that.In my neck of the woods many silver coins are in the 6 inch depth area, but many are 10 inches plus and an Explorer has the ability to go deep. I hope you are swinging slowly as that equates to superior depth with an Explorer.Recently buried coins and above all air tests do not give good results relative depth comparisons..If your buddies are digging them deep might want to try out one of their settings and above all go slow. Heck my first time out using quickstart got 6 wheaties a walking half and an old merc.( 6-10 inches) and all I did was use quickstart..adjust the threshold to my ears amd beef up the sensitivity into the low twenties..In addendum would go out with one of your buddies using the same settings and when he gets a deepie...see what it sounds like on your unit.Nothing like hearing the sound of the real thing...Patience my friend as when it all falls into place going to have a suprior unit in your hands..

 

[Anonymous]

Dan, good points and suggestions. I was going to add that Minelabs suggest using TONE at Audio 1 for increased depth in trash areas if one is good at hearing the differences in tones. It looks to me like Audio 2 and 3 increase the filtering so can decrease depth. I would be sure an noise cancel as that change the search channel and then try the Tone at Audio 1. After sleeping on this I would also be sure the variability and threshold tone is set in a way that he can hear the differences in tones clearly.
HH, Cody

 

[Anonymous]

Cody,
What I am about to say are only my personal feelings based upon my experience.
GROUND MINERALIZATION DOES EFFECT THE PICKUP SIGNAL SEEN BY THE DETECTOR ELECTRONICS
#1 The automatic ground balancing feature of the Explorer examines and qualifies the ground mineralization. Thereafter, the detector ignores the ground mineralization signal if there is no target present under the coil.
#2 If there is a target present under the coil, then the detection circuit sees the composite signal of the target plus the ground mineralization.
#2.1 A target responses is given if the composite signal exceeds the threshold setting (as set by the Sensitivity setting)and the target falls in white part of the screen. Otherwise a null (or no response) is generated.
#2.2 The deeper (and fainter) the target portion of the composite signal, then the greater the effect of the ground mineralization.
#2.3 I believe that is why (that in the areas that I hunt) almost all of the good targets found below a few inches are shifted considerably to the left on the smart screen (as compared to air testing).
What are your thoughts on this.
HH,
Glenn

 

[Anonymous]

Todd,
You wrote <span style="background-color:#ffff00;">maby I should learn on quarters and then move up to dimes so to speak.</span> Why not bury both in your coin garden? You might also bury some coins a different depths to see how the signal changes as a function of depth.
HH,
Glenn

 

[Anonymous]

Glenn, this is a basic explanation of how I understand that Explorer deals with soil minerals. The first is to Noise cancel and select the best spectrum. While the explorer is a time domain rectangular pulse detector it does demodulate the received signals to produce instantaneous and historical signals to use for ground balance and the best of the 28 frequencies for time domain processing. If one looks at the cycle of two pluses the first is the pulse for ground compensation. Only when the eddy currents in the soil have decayed to zero do they look for target signals. The demodulators' select the best signal of the 28 based on the frequency of the metal. <span style="background-color:#ffff00;">So, at least in theory the ground minerals would be a non-problem </span>if the detector operates below 100khz with the method they use. The bottom and top frequency are set and the spectrum is shifted based on Noise cancel to compensate for the soil and other noises.
In all metal the minerals should be almost eliminated in theory. <span style="background-color:#ffff00;">The problem as you know with theory is that no electronics is perfect and does age so the reality is there is some problems with minerals</span> but they should be very small. <STRONG>I tried to indicate that the problem should be very small.</STRONG> The method of ground balance is a major factor in the design of the Explorer and why it is pulsed time domain instead of frequency domain, which requires more exact circuits and is more costly.
Once the signals, instantaneous, historical and targets are demodulated then we have essentially one signal to process which is in the time domain for identification. At this point I don't believe it is a ground mineral problem but discrimination.
I have been testing some of this and the most important control I have found if I follow the correct procedures in the User Manual is the use of FAST/DEEP in conjunction with the audio sound. Also correctly setting the limitations, variability and threshold tone really makes a difference on my test coin what I hear. It is cold today so I only got to the test site for about 10 minutes.
The bottom line is I don't have problems with ground minerals but think it is ground contamination that is often confused as ground minerals. However, at IM-16 this should be easy to catch as small bits of trash or deep trash targets and iron.
I know this is involved by no one has to read it.
How does this sound? I will look at the patents closer over the next few days so this a first blush at what I thik they are saying.
Cody

 

[Anonymous]

Cody,
I have not studied the patents in great detail, so I can not speak with any real authority. Nevertheless, here are my thoughts.
#1 NOISE CANCELLATION EFFECT ON GROUND BALANCE
I was intrigued with the thought that the first pulse was for purposes of ground balancing. Does that come from the patent or is it your conclusion? It is hard for me to see that the noise cancellation process has much to do with rejecting ground mineralization. I always thought that noise cancelling was for external electrical signals rejection (which can be transmitted through the gournd as well as the air).
#2 WHAT IS LOOKED FOR IN EACH OF CYCLES OF THE RETURN SIGNAL
It is my thought that each of the return signals from the pulse cycles is examined for both ground mineralization and target information.
#3 THERE IS MUCH MORE TO GROUND MINERALIZATION EFFECTS THAN EDDY CURRENTS.
Eddy currents in the ground are only half of the total story. It is possible to have severe ground mineralization problems with zero ground eddy currents.
I believe that ground eddy currents result from ionization of the water in the ground and/or small pieces of conductive material in the ground. If both of these factors are absent, then there is not much mechanism for eddy currents to flow.
But, if there are ferrous granuals (such that the conductivity is very low) in the ground, then the effect on the magnetic field can be very great even though the eddy currents are essentially zero.
I would not be terrible surprised to find that I am wrong on any or all of the above points.
Regards,
Glenn

 

[Anonymous]

Change one facet and it may affect another, we can theorize, some much better than others due to backgrounds in electronics etc...mix in ground mineralization and a horseshoe in the immediate area and theories may change. I really feel time in the field and experimentation is the name of the game. After a while you will know what works for you and you will be posting nice finds...As far as sending into Minelab might be a plan, talking to tech's they will tell you in lab enviroments 7 or 8 inches of depth is tops. In field conditions I have gotten 10 inch plus silver dimes so indeed hang in there and have patience..I speak from experience as I have hunted areas beat for years and have come up with deep silver and many of the forum member have also.

 

[Anonymous]

If you have deep black dirt 12" deep then you should get more than 7", unless you have a mineralization issue (I sometimes cannot get past 8" near floodplains for some reason or another). However, if the clay starts at 8" or less then you might have a problem with the clay layer. Sometimes this layer has lots of mineralization trapped in it (especially if you are near a river), or heavier trash like nails and lead and you might not be able to get 8" on a dime. (Nothing gets much deeper than the clay layer, also).

 

[Anonymous]

the finds are out there and burying new finds aint gonna help ya find the real deal <img src="/metal/html/shrug.gif" border=0 width=37 height=15 alt=":shrug">
go out and look for real targets and no test finds at all... do it for a few moths you will get the hang of everything by useing it not testing it <img src="/metal/html/biggrin.gif" border=0 width=15 height=15 alt=""> good luck

 

[Anonymous]

Glenn this is where I am at this point in time and as I indicated after a first read that anything that was more than a casual glance. I will now go back and answer many of the questions the survey of the material raised.
There are two pulses as you have observed of which one has a very shot period and the other a fairly long one. If I hold that thought and think now of the soil matrix and targets. There is a great difference in iron minerals and salts when compared to magnetic metals and nonferrous ones. If I combine this and consider a first pulse with a very short period the magnetic domains in the iron mineral will align with the flux field. When that field is removed the most of the iron minerals magnetic domain will flip back to their original state. If the receiver coil is sampled just after the short period pulses then the current in the TX coil is zero and the receiver coils has signal that is negative in sign. This is ground noise and also becomes historical data if followed by a pulse with a long duration. The second pulse of a long duration also has ground noise which provided a second signal with a negative sign but also due to the long period has significant target signal due to the much slower decay of current in magnetic and nonferrous targets.
The demodulators are in pairs and have negative sine data and positive signal data that is averaged in the output by summing resistors and filtered for any noise that got through. One pair of demodulators is for the low frequency component of the received composite signal, one pair for the middle frequencies, and none pair for the high frequencies. Each of the outputs are averaged, filtered, and fed to the microprocessor to be "worked over" to be presented to the user.
I don't believe the first pulse period is of much value other than to collect soil matrix data mostly about soil minerals and salts for historical data for the second longer period pulse. It needs to be short and not sufficient to cause the magnetic domains in the iron minerals to stay fixed but rather to return to the state they were in when the detector's flux field aligned them.
I am fairly sure that eddy current flow is very different in the soil but not really sure how. I believe Minelab uses that their technical data so just went with it. In reality the soil and target act the same was as a core between the primary and secondary of a transformer.
It is my opinion that Noise cancel is for both soil mineral noise and other noise but right now I cannot say for sure that it is. This is why I say this. The soil minerals respond to different frequencies which is why some detectors seem to work so much better in different areas based on the selected frequency. A higher frequency is attenuated more so has less depth due to the sensitivity to the iron minerals. A low one has less sensitivity and therefore more depth but is not as sensitive to small targets. Noise cancel works by changing the pulse periods, I think, and therefore the frequency spectrum. If only to reject noise other than ground noise from soil minerals then it sure seems like a difficult and complicated way to reject other noises when filters would do the jog and be much more simple to implement and design.
I think when you place the coil on the ground and noise cancel you reject noise and establish a base line, or channel, frequency spectrum to start detecting. The standard spectrum is channel 5 pretty much like auto ground balance detector has a preset. I have played around with this control and set it in manual and then gone to auto to see how the channels change. I set the noise cancel with manual and think I do better and will give each channel a minute at least. I almost always can find a channel that is better than channel 5. I think this is a very important function but have stayed away from this on the forums. I find some very interesting operating changes when used in conjunction with DEEP/FAST and Response from normal to audio 1. I am reluctant to mention how strong and deep a target sounds if these are set properly.........in my opinion.
HH, Cody