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Depth test results reveal sensitivity and gain settings do not increase depth.:clapping::clapping::clapping:

M

Mr-depthtester

New member
Some tests i did today on buried coins revealed something amazing .

INCREASING SENSITIVITY OR INCREASING GAIN HAS NO EFFECT AT INCREASING DEPTH ON BURIED TARGETS.
 
about 2 weeks they have been buried. All i am saying here is that gain and sensitivity settings do not alter the electro magnetic fields strength. You can turn the sensitivity right down and turn the gain down but the field from the coil still goes down to the same depths. It appears that we are not actually getting extra depth by cranking up gain and sensitivity , i believe we imagine it in our heads that we are getting deeper if you know what i mean. All we are doing by cranking up sensitivity is causing instabilty of the amplifiers inside the detector!
 
No sir what you mean is you cannot hear the signal , your detector will still be reading this deep coin and thedetectors electronics will be responding , all you are doing by turning down gain and sensitivity is like turning down the volume so to speak.
 
n/t
 
If you have a target that sound weak....Increasing the Gain enhances the target volume. Target at 5 inch's or at max depth have the same target preseption of depth in Volume at max gain.

At the setting of 6 or 7 you still are able to tell the depth of the target by the volume of the target.
 
you may have buried the targets you have tested in soil that may have very little effect on the Explorer. It also seems that these targets are being detected in a way that would probably be no different to a simple air test.

The Explorer's abilities in detecting deeper will occur in soil that most other detectors will end up losing depth in when trying to detect the same targets. The ability to hear a target that has been detected deeper can be increased by increasing the volume of that good signal through the GAIN control.....and PROVIDED it is NOT being totally or partially masked by another not so desirable ferrous or non ferrous target and/or adverse soil type, you will hear it on it's own as a good target IF it is in range BUT maybe you may hear a good target as a crap target that could sit just out of the Explorers depth range. This is one reason why you would use your depth gauge as to determine whether you may want to or not to wnat to dig and investigate such deep targets. This is a wild card option. Again your choice.

Also be prepared for mixed audio signals with jumping cursors. A good target will not always sound or seem that way until it is separated from what ever else is being detected around under or over it.

This increase or decrease of the sound volume of the GAIN on good targets(along with those really annoying spurious signal intrusions of the not so good targets or stray frequencies) is there to give a dynamic to the detected depth of the target and mostly if it is required. It's a user friendly input. You make your choice. The GAIN setting could have been set on FULL from the word go but fortunately that user function has been made flexible with user adjustably .

So yes, there is NO increase in the Explorer's ability to find a target deeper simply by upping the GAIN. It will allow one to hear or get an audible idea of the that target, better or if needed louder, if that's what the individual using the detector needs to do in there style of detecting.

The SENSITIVITY control in all of this needs to be adjusted for the flexible set up parameters that Explorer offers.

This MAY equate in an increase in depth in certain soil conditions and when using differing size coils with the way the Explorer behave and in the way it be can be set up.

Have you tried the differing variants of the way the Explorer can be set up and seeing what an increase in SENSITIVITY does when you set the RESPONSE at it
 
There are two persistent myths that need busting.

Myth 1 - Running the sensitivity too high in bad ground puts too much power to the ground overloading the machine.

Myth 2 - Lowering the sensitivity in bad ground reduces power to the ground thereby improving depth by not overloading the machine.

If you connect the Explorer transmit winding to an oscilloscope and adjust your sensitivity up and down you will notice that the transmist signal strength does not vary. While building custom coils for my Explorer I have had my sens at 1 all the way to 28 and the transmit signal is always the same.

Therefore the Explorer transmits at 100% power regardless of user settings. Therefore one cannot overpower the ground or put less power to the ground via user settings.

That said what really happens when you adjust sensitivity? Only the Minelab engineers know for sure, we can only guess.

I have had deep targets with my sens at 28 manual that gave a not great but decent signal. I then began lowering my sens and as I did the signal became weaker and weaker until at one point the signal was no longer there and I had a steady threshold when sweeping the target. The same is often true for switching to semi-auto sens. Often the signal vanished when switching to semi-auto.

This is why some camps say the higher the sens the better, but wait! The trouble is this does not hold true 100% of the time. Sometimes when I have had a deep target with my sens at 28 lowering my sens resulted in the signal improving, crikey!

This suggests that things are not as simple as we would like them to be. It suggests that targets (this includes the ground) do not increase and decrease in signal strength at the same rate when you raise or lower the sens. For example lets say you have a deep coin with a nearby rusty nail and some semi-bad ground. Lets say with the sens at 22 the coin is the stronger of the three targets (coin, nail, ground). As you increase the sens the ground or nail may overtake the coin and drown it out.

What aboug gain? The only thing I'm pretty sure of is that gain is processed after sensitivity. Therefore if you adjust your sensitivity lower to a point that the target is no longer there, boosting your gain to 10 won't amplify a target that is no longer there.

But again things are not quite that simple. There are two general camps, those who run a high gain and lower sens (sometimes semi-auto) and those who run lower gain and higher sens. Both will make finds the others cannot. Which method produces more finds in a given area depends on the soil and site conditions.

The guys running lower sens and high gain WILL make some deep finds the high sens camp will miss. This is because higher sens results in more faint high pitched signals from the ground. Was that last faint high pitched chirp a deep silver coin or one of the half dozen high pitched ground chirps you get per swing from running your sens hot? You can't see the forest for the trees.

On the other hand there are clearly deep signals that simple vanish with the sens at lower settings so the high gain camp will miss those.

At the end of the day there is no one approach that is better than the other 100% of the time. In fact if a given site has stopped producing using one approach it makes sense to adjust your settings and try another, you may make a few more finds.

This can be true for discrimination also. I often run all metal but with rusty crowncaps notched out. I have dug many silver coins that were hiding underneath more shallow rusty crowncaps. The odd thing I noticed is this, with the crowncaps notched out the machine locked onto the silver pretty good. But when I switched to true all metal with no discrimination (I do that as a rule when pinpointing targets) the machine instead locked onto the rusty crowncap solid and pulled the cursor down to the rusty crowncap area. Had I not been running with the crowncaps notched out I would have walked over that coin in all metal.

But again its not 100%, sometimes the oposite is true, I'll get a signal on the coin in all metal but with the crowncaps notched out I get only a null. Arrrgh!

Charles
 
At some sites I experience the same thing - lowering the sensitivity improves the signal. But for the most part in most of the soil conditions increasing the sensitivity allows for me to pick up those deeper targets. When I have to lower my sensitivity I get a little nervous like I'm going to miss the deep stuff.

BTW -
You still hitting those hunted out parks? Anything left for me?

Bob
 
Charles, All that being said, what do you "Generally" run your machine at. (Lower sensitivity / High Gain), or (Higher Sensitivity / Low Gain)? I normally set my machine at (25) Sensitivity and (7) gain, with great results. I also back the threshold tone back to (3).And always DEEP.
 
Having plundered NY for many years I up and moved to New Hampshire a month ago so now I have a whole state of new parks and beaches to begin hunting! :D
 
Nearly the same as you, Sens 26 Gain 7 Deep ON Fast OFF, all metal most of the time but will notch rusty crowncaps out if I'm seeing a lot of them.

Exceptions:

If the soil is mild and I'm not getting a lot of soil falsing I'll bump up my gain.

If I'm in heavy trash with limited time to hunt or just in the mood for a more relaxing hunt I'll run my trash program which is the bottom half of the screen blacked out with windows for nickels and gold coins. Top half open allowing in both iron and coins.
 
I do not know how accurate my theory on how the sensitivity circuit works actually is but here it is anyway.
I think of it as a noise gate for the receive circuit. I also think that Charles hit the nail on the head so to speak in that the Explorer transmits at 100% all of the time.

Highly mineralized ground returns a stronger signal to the detector than milder ground, but a weaker signal than strong targets.
By lowering the sensitivity I think that you are cutting off the weaker return signals in much the same way that a noise gate works with audio amplification circuit.
If a return signal is not strong enough to make it through the noise gate it is simply ignored.

When you raise the sensitivity you are lowering the noise gate so to speak so that weaker return signals make it through including those generated by highly mineralized ground or other EM interferance.

According to this way of thinking it seems logical to me that since deeper/smaller targets return a weaker signal than shallower/larger targets, if you reduce the sensitivity (raise the noise gate) to eliminate bad ground or EM interferance you could lose the weaker deep/small targets return signal as well.

If the soil is mild and you can raise the sensitivity (lower the noise gate) the weaker deep/small targets return signal will make it through the noise gate and you will hear them, but, signals from bad ground or EM interferance will make it through as well resulting in "chatter", false signals and instability.

I think the Gain circuit is just a hearing aid. The deep/small targets that generate a weak signal are much lower in volume than a shallow/large target. This is great and gives you an "audio depth meter" providing that you can hear it. The Gain merely amplifies the audio signal generated by the detector when it finds a target that returns a weak signal so that you can hear it.

I would appreciate your opinions on this theory. Remember though, it is just that, a theory. I am not saying that this IS the way it works, merely that this is the way that I THINK it works.

HH
 
Thats a good post and pretty sccurate too charles. I think what people need to know though is this simple fact = Increasing sensitivity gives no extra depth all it does is enhance a signal that is already there. I think a lot of detector users think that turning up the sensitivity gives inches extra depth when in fact it gives micro changes in detection depth. . We are talking about maybe 1 cm "extra depth" by increasing or decreasing the sensitivity from the manufacturers pre set turn on and go settings. I think 1cm is all you can expect to gain over minelabs factory settings no matter how much you play about with sensitivity or gain or any other setting like recovery speed for instance. When you turn your explorer on and detect in say manual sensitivity 22 then you are detecting extremely close to the maximum possible detection depth and either increasing or decreasing the sensitivity by a few numbers will do very close to NOTHING at getting better depth , ok you may get a very small gain in depth but you are talking 1 cm maximum!.
 
, which I know might not be absolutley correct at all times.....
I think it's pretty close in this case and maybe a partial answer to this "mystery" about what part SENSITIVITY plays....


Sensitivity is the detector
 
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