Discrimination and loss of depth

I have always read that discrimination results in less depth. Although I am sure this is true I do have some questions on this issue.

1. Why does a detector loose depth. I can understand it missing targets because they are discriminated but do not understand why you would also loose depth on a non discriminated target.

2. Do all detectors loose depth or only some. Does discrimination change the depth of a Etrac, how about a CZ, or does it only effect single freq machines.

3. If I have a detector with a discrimination mode and a motion all metal mode will the depths be the same if I have my discrimination on zero as the motion all metal mode?

4. I hear so many people warn against discrimination so you do not miss targets. If your machine has different tones for iron through high conductors does it makes sense to discriminate with anything other then your ears?

5. What about PI machines I know some now have some level of Iron discrimination does that impact depth as well?

Quick answers...

choose what you wnat to know more about..And I or someone will devote a better answer..

question 1. Why does a detector loose depth. I can understand it missing targets because they are discriminated but do not understand why you would also loose depth on a non discriminated target.

For the simplest of explanations is it looses sensitivity the more disc is us turned up..Put a machine on nail rejct and the highest sens right at the edge of instability then turn the disc up and eventually it will loose the instability.. the sens gets detuned to all metal's the more you become biased towards lower conductor's...The more of the signal you disc out the more of a good target signal it will take to signal..

A quarter is a quarter and airtest say 10 inches in nail disc....you are very biased to the high conductor's like this...turn the disc up to pulltab and you are very biased to rejecting lower conductor's...now the quarter will only be heard at 7 inches.. the quarter has not changed conductance but the machine has become more biased to rejecting conductance than accepting it...so now the quarter need's to be bigger to gain the depth back to 10 inches more like a 50 cent piece size..

Sort of like looking at a star with naked eyes .. very easy to see.. put on sunglasses and the star get's dim put on 2 pair of sunglasses and the star can disappear...your covering up the light...with a discriminator you are covering up the conductance...
this is in simple terms ...LOL...

Question 2. Do all detectors loose depth or only some. Does discrimination change the depth of a Etrac, how about a CZ, or does it only effect single freq machines.

Not all machine's loose depth...the etrac and cz do not they use a audio disc circuit more like notching .. instead of an electrical circuit...Single freq machines can do the same as the multi freq's...

But remember just becasue you dont loose depth you will still loose target's if too much disc is used..Object's can read lower into area's you have choosen to reject and be nulled...

Question 3. If I have a detector with a discrimination mode and a motion all metal mode will the depths be the same if I have my discrimination on zero as the motion all metal mode?

I answered this last week in a more detailed post...A motion all metal mode threshold based is completely different from motion discriminate mode..and as a general rule the all metal wll be deeper...Just by the very nature of the design on in ground target's..

Question 4. I hear so many people warn against discrimination so you do not miss targets. If your machine has different tones for iron through high conductors does it makes sense to discriminate with anything other then your ears?

Thats the best way to hunt...I prefer 2 tone one for iron one for all other's..and allow the iron tone to break where I set disc at ...multi tone is still a form of disc I.D. and while allright for cherry picking it will still misplace items in the wrong tone ...if you are seriously wanting to work a site of all but the bothersome nails then 2 tones with user defined tone break is optimum and a must...2 tone is a form Of I.D. also but helps alot.

Question5. What about PI machines I know some now have some level of Iron discrimination does that impact depth as well?

Minelab is the only one with an iron disc circuit...and it only really works to a certain depth somewhat then all is heard beyond that..

the TDI's and Infiniums have 2 tone's but they are not iron disc circuit's they are size circuits for the most part...large iron sounds good small iron sound's good the tones just switch form low to high by the decay rate coupled with a ground bal.. and the ground bal tone circuit does effect depth over a straight P.I. but allows it to work in very bad ground....the tones is more or less a by product of the ground balance system..and can be used on site's with certain size bothersome iron like nails ..but it's complicated...

but P.i.s will get to target's Vlfs can not see if the dirt is very bad...thats there forte...maybe one day a disc circuit will be developed..

I know these are simple answer's..Tom or someone else might explain things better..

Keith

You answered the questions very well. The rule to remember is to use as little discrimination as your brain can handle. Every site will be different because of the trash.

From detectors I have used and used a few a CZ looses little or no depth and same goes for the old Wilson Coin and Relic with high disc.

Not all units are created equal but most will lose depth with high disc to varying degrees

Any other takers rel the depth and high disc issue if so hop in...

Thanks Keith - great answers that helped me understand better about discrimination and it's affect on depth. This is the reason I love this sight so many intelligent people that help us all understand the sport better.

Thanks

Bryanna

I asked Dave J. (lead engineer @ Fisher/Teknetics) whether my Omega would lose any depth with an increase in discrimination. The answer was 'No'.
As Dan-PA points out, loss of depth..if any.....is machine dependent. Years ago the older machines would definitely lose depth with disc increase. Don't know if digital technology now allows this loss to be circumvented/minimized. Anyone know the answer?

Clearly there are different schemes to dealing with disc. I like how Keith said some use what appears to be a notch like system on the audio. The V3i (with disc value audio tones set to zero), E-Trac and now my Jupiter are like this. I don't see a drop off with disc. The jupiter only goes up to the pull tab range on disc but I tested this with both high and low conductors and no change at all in depth. The Jupiter seems very near the speed of the Deus however and...

The Deus had a HUGE difference in depth from just adjusting the disc in the iron range. Clearly they are doing something quite different with the Deus as it is a relatively new and top of the line machine. But, since it's designed to work in heavy iron, I think they made some sacrifices.

Remember too that there are other issues out there that are just as important as depth ......As powerful as the E Trac is , using too many filters will spoil and otherwise good hunt too, much like Keith was talking about with the sun glasses ....I tend to think of it like running a car in the Summer time .....Runs great until you turn on the air conditioner ......The motor bogs down and you need more power to run the car at the same speed ..... Same goes for the E Trac ...... The beauty of the E Trac is that it has a matrix system made up of tiny squares which represent coductive and Ferrous numbers .....Each target has a Conductive and Ferrous number .....You can zero in on each target and descrimnate it , or keep it .......This way you don't have to choose to discriminate from a Nickel on down thru Iron .... Or Pull Tabs down thru Iron ..... I pick and choose EXACTLY what targets I want to discriminate and leave the rest alone ......Jim

From personal experiences with the E-trac, coins and jewelry can have high ferrous values at depth in heavily mineralized wet saltw@ter beach sands. Small gold rings and small gold pendants generally have a 30+ ferrous readings at the beach where I hunt. At some areas on the beach, they read a constant 35 ferrous at depth. The black sands, high levels of iron and iron rust, and wet sands all contribute to this condition. Most of the small, very low conductive targets that have high ferrous readings that I have dug have been non ferrous. Dectectorist in the past may not have been aware of this and missed most of the small gold jewelry at this beach.

Using any discrimination on very low conductive targets at depth on this beach might cause the E-trac to lose sensitivity to such targets. This works very well with very low conductive targets because the mass majority of iron targets have high conductive values on the E-trac. Stainless steel is the main exception.

Detecting since Feb, 2010
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