Do you think your detector loses depth when you apply discrimination????.....Please explain clearly, what you mean.....MattR.UK

[MattR]

I have been reading some earlier posts, and noticed that hackneyed phrase being used, "loosing depth by discrimination"


Do they mean that their detector isn't DETECTING AS DEEPLY AS IT WAS prior to applying discrimination?????????

If that is the understanding, then I respectfully suggest they are mistaken.....

In which case they need to re-phrase that age old 'chestnut'.

It is about time that phrase was buried forever, and replaced with one that conveys what is actually happening.

The only thing that you can normally do through available adjustments to make your detector lose detection depth, is to reduce your sensitivity.

ALL OTHER ADJUSTMENTS THAT APPARENTLY AFFECT DEPTH, ARE IN REALITY, THOSE THAT LIMIT YOUR AWARENESS of what IS STILL BEING sensed by your unit........i.e. NOT being actually lossed ( Not being detected)

I offer a replacement phrase for "Discrimination looses depth".

It is, " Discrimination audibly restricts those detected targets which I CHOOSE NOT TO HEAR".


[size=large]NOT, " DISCRIMINATION LOOSES DEPTH"[/size].......................MattR.UK.

p.s. I've got my helmet on, and the sand-bags are in place, so fire away.......

 

[bfodnes]

You are in a way correct Matt but you are also wrong.

If You apply discrimination to your explorer you will still find a Silver 10 pound bar at the same depth as before.

What You lose out depth at is the lower conductive targets close to the disc upper setting.

It is like looking through a huge hole in a concrete fence out on a highway, you clearly see both small cars and motorbikes, even what brand they are.

now,, try looking through a smaller hole, you will now only see the trucks clearly, the small cars and motorbikes you cant tell what it was and maybe not even the color. Forget about brands and makes.

?????

hehehehe

 

[Rigit]

On ET and EX detectors, discrimination has no effect on depth at all it just inhibits the audio tone and cuts the threshold or what we call a null.

 

[MattR]

Thanks for your thoughts on the subject, B., but I don't think the analogy quite fits the case.

The size of the hole doesn't inhibit the contents in the view, only the brightness and resolution of the scene.

So there is no 'discrimination' involved as you surmise.

I give you a parallel to your 'Hole in a concrete fence' theory. i.e. Blinkers on a race horse.

You are in wrongly attributing the function the iris of the horses eyes, to that of any blinkers fitted.

Whereas blinkers primarily restrict the field of view..(Discriminating what the horse can see, off axis).

Reducing the size of the iris is comparable to reducing the sensitivity of the optical system. (making the hole in the wall smaller)

Imagine your 'hole in a fence. was replicated by a 'camera obscure' set up.

i.e. A light-proof tent with a small hole in the side.

An inverted image of the exterior scene, would be produced on the opposite internal wall of the tent.

Reducing the size of the hole would reduce the brightness of the image, but its actual definition (focus) would be improved.

Nothing in the original scene would be 'discriminated out', as claimed in your analogy.

Any truck. motor bike etc., would still be visible visible, albeit at a lower light level.

To achieve your desired effect of removing some items from view, you would need to erect a fence a few feet in front of the hole, and leave a narrow gap.

That then would act as the discriminator for the 'peripheral' contents of the view.......

No........?


p.s. I think you saw something naughty through that hole you made in the concrete fence.....Confess....What's the He he-he for then?

Matt.

 

[mattockman]

n/t

 

[Tom_in_CA]

The old days of ascending/descending discrimination knobs are gone. In those days (TR disc.) you would indeed loose depth when you went to knock out nails, foil, tabs, etc.... But nowadays, it's just allowing what "numbers" you edit in or edit out", They never cease to be just as strong of a hit in those areas of your screen or TID scale, whether or not you had them heard or not heard.

But here's where the old-addage continues to be true: By allowing more of the TID scale in (lowering the disc, yet seeing the bounces/TID on your screen) allows the user to hear the bounces and of the cursor or needle or readout or whatever. And we all know that deeeep targets don't always bounce consistently, right? So for example, a shallow dime may hit 100% of the time right on "dime". But a deeep old dime might bounce low, then bounce high, and back & forth, depending on how well centered over the target you are, the swing speed, etc... right? So by having the disc. low, you are subconsciously drawn to random hits, even if low, causing you to subconsciously "check" those signals closer, x-marking the spot, fiddling with the swing speed, etc... seeing if you can "bring it in". Naturally if it continues to always hit low, no matter what you do, you may elect to move on. But if you can find that it's "trying" to come in high, you may check it out, right?

But get this: even though random swings may come in at the higher conductive point, you would NEVER have known to have double-triple checked the spot, to begin with, had you not been in low disc. to begin with. That is, you'd merely have had a null, that would never have drawn your attention to the spot, to begin with. For that reason, it just "feels" like you are getting more depth in disc.

It's no different than the double-tone mode of the XLT or Eagle: People felt they were getting more depth when they elected to hear the rejected targets in the low tone. But truth be told, the accepted tones never actually got stronger or deeper. So why were people feeling like they got more depth? Because when you're swinging about the field, fringe targets at the edge of the coil's field would be heard in the reject tone, causing you to subconsciously double-check and center over any suspected targets, allowing you to have a grasp and feel for what you wanted to "eventually" hear better. So the user felt like he was getting more depth. Am I making any sense?

 

[Dang]

I wish I had a established test garden then I'd just go out and see for myself. I would have a target that can barely gets through in All Metal, Then set some Disc making sure said target is still within the accepted zone....If I still can hear it, then I would assume that Disc has little or no effect on depth. If one had a detector where the tid still responded over rejected items, then one can see the if Disc can cause a good target to be rejected.In other words still being detected but now being rejected. (Does that make sense?)

 

[bfodnes]

No, the analogy is not wrong,,,,,,,

The less disc u got the better will a detector see a small target.

Any detector...

You can test that by discing out all but a 5 by 5 pixel window on a small hammered and bury it....

 

[digitrich]

First off, what some are forgetting or never knew is that when a target, a "deepy", is just barely at the edge of your coil's maximum detection depth you don't get a tonal response from it. Instead your threshold blanks. Now if you have the machine set up with any discrimination whatsoever, you could never hear that blank amongst your discrimination blanking and judge it as a possible deep target. These are the "expert" targets that others pass over and the reason most people buy a ML, because it is the deepest, most accurate coin ID'ing detector on the planet (entire Explorer series). If someone knows of one better, let me know, as I WILL buy two tomorrow. The whole purpose of setting a threshold level barely audible is to be able to hear these type of responses.

Des Dunne's paper on the ETrac mentions several problems with using discrimination and yes that pertains to deeper targets especially. You can find that paper under FAQ on the ML website and I posted a link to it in a previous post. As a target gets deeper, further away from the coil, it's signal gets weaker and weaker and it's ID gets less and less accurate, and the detector is dealing with larger and larger quantities of soil mineralisation signal to get through to even pick up the desired target signal, which can be hundreds of times smaller than the soil signals. So your discrimination may mistakenly identify the good target as a disced out target and blank. This again will happen with your deepest, weakest signals. It does not matter if magically this detector gets 10 times the depth of the previous Explorer models, it doesn't matter if they invent the finest most perfect see through capabilities. At the edge of accurate ID detection, where ever that is, no programming is going to help. It is a matter of physics, a math problem, and that math does not change with the advent of software. Any metal detector, including the ETrac will achieve better depth with less discrimination and always will.

As for the Heavy Trash setting on the ETrac, it is reporting the non-disced target's response instead of the disced null; even if its signal is weaker than the surrounding disced trash. It only does that on solid repeating signals, which ID in the non disced portion of the screen. 90% of: in trash, deep targets will not be clean ID's as the targets both blend with one another and the soil, again, especially as you go deeper. You see Matt, if this really worked as well as we wished and could pick up coin after coin that previously was masked by surrounding trash at depth, no one who owns an ETrac would be on here posting, we would all be out digging up 40 and 50 silver coins a day. It only seems to work on fairly shallow targets for me so far. This NEW technology is in it's infancy and it would be foolish to assume it has already been perfected the first shot out of the box. Hopefully it will get better and even more effective on the next ETrac, in fact, I am expecting it to. But if you believe that ML has just invented the only machine on the planet that does not loose depth while using discrimination, well, I can't help you with that. That's something you will have to figure out for yourself.

 

[digitrich]

n/t

 

[Mike Bearden]

Like a lot of old timers here, I've used many name brand detector over the years and can think of one or two that doesn't seem to have the depth affected by disc whatsoever verses all metal.

How about the X-Terra 70 ... the Fisher F-75 ... if there is ANY difference .... you'd have to PROVE it to me and I've ran them in some of the absolute worst dirt and iron imaginable.

Now I don't know about the E-Trac ( haven't got one yet ) but it sure looks to share the new digital processing look of the X-Terra .. anybody know for sure ?

I agree that disc will in-fact hurt depth on some units, hell .... most units for that matter ... but quite a few new models with digital technology don't seem to suffer at all in disc from my experience
.
I've dug some very deep tiny non'-ferrous targets while using quite a bit of disc with these units and sometimes the ears need a break from all that crap in the ground, especially with powerful higher end detectors.
Granted I like to run the SE in wide open iron mask MOST of the time and feel more comfortable that I won't miss anything that way including those faint threshold only drop sounds.

 

[bfodnes]

Absolutely correct.

Even if the technology are made not to suffer from high disc levels you will lose depth.

Cause your first hit on the coin may be inside the disced out pattern or notch on your detector.

Bigger window, more hits.

 

[dewcon4414]

You have a AC and DC side to the coil the AC induces the DC and sensitivity is reduced when nulled by a disc target. Any time you loose sensitivity you are looseing depth. Recovery is slower on nulled targets than on targets producing a sound which means you could also pass over good targets if you are "taking you detector for a walk" instead of even slow swings. Also when you disc you loose sensitivity to some targets close to the disciminated targets number.

 

[jbow]

you still can't beat a Sovereign running in AM?

Just asking...

Also, is blanking the same as a null?

Thanks,

Julien

 

[jbow]

I have an established, about 6 years, garden over at my old house... luckily my daughter bought it! I'll try to get over there next week and check some targets with AM and Disc using both the SE and the E-TRAC. I am curious to compare them.

I have a lot of coins and trash buried there, 70+ targets.

Julien

 

[king-ghidorah]

I have an established, about 6 years, garden over at my old house... luckily my daughter bought it! I'll try to get over there next week and check some targets with AM and Disc using both the SE and the E-TRAC. I am curious to compare them.

I have a lot of coins and trash buried there, 70+ targets.

Julien

Keep us posted.

 

[Captain Kirk]

Matt,

I agree with you completely. The issue reminds me of the oft heard question (rephrased) "If a tree falls in the forest and your hearing aid is turned off, then does it make any sound?".

HH,
Glenn

 

[bfodnes]

Does it make any difference.

A tree in head might be worse then no signal on a coin but its just the same.

It doesnt matter to us if the detector goes just as deep with no disc or a tight pattern.

Now another view at this.

Are You saying that all of us who use open screen or minimal iron mask does it for no reason.

We should have just the same coin finds with a tight pattern optimised for coins. ????? I know that is bull.

With a tight coin pattern You can easily lose a coin at 2" that you may have dug at 7" with an open screen.

I call that loss of depth due to too much applyed discrimination.

 

[Captain Kirk]

I think that what Matt is saying is that the detector still sees everything (albiet obscurred by depth and/or other close by targets) regardless of the discrimination setting. But, after analyzing the target, the detector then recognizes that the operator has requested that the detector not tell the operataor about every thing it sees. In other words, when you increase discrimination it does not change what the detector sees. In only changes what the detector tells you it saw.

HH,
Glenn

 

[Captain Kirk]

We have to be really careful about the semantics here.

I agree with your point that the end result is that you do not find as many of the "iffy" targets as the discrimination is increased. In reality, this is what is really important. But, we should not confuse that with the detector performance. The detector still sees the target the same regardless of the discrimination level. The descrimination setting only alters what the detector tells you about what it sees and not what it actually sees.

HH,
Glenn