General Detecting Question.....very curious about this!

[DavefromCt]

I have the v3 and have had many other detectors for 40 years....I know PI goes deep but not usually recommended for land because you need some discrimination of junk. Now...I notice that many detectorists use the 'nulling of the threshold tone' to pick up deep objects. I've never done this but from what I understand, if it nulls out, that means it's probably junk or it could be a good target. I would be constantly digging if I used this method, and if people do prefer this, then they might as well detect in all metal or use a PI on land right?....I'm very interested in a discussion about this because I may have my facts wrong, but every time I read the manual on a new detector they say that if the tone nulls out it's junk. Thanks for any input! -Dave

 

[BHNugget]

Last weekend I dug up a bunch of shallow targets that were nulling (blanking) the threshold just to get them out of the way in an area Ive found some nice coins.My concern was the nulling of the threshold (because of so many junk targets) was blocking good signals.I spent about three hours getting junk out of the way pinpointing the nulling targets, only to find I hadn't missed anything as far as I could tell.A short while later in the same area I got a 70s VDI blip (it was repeatable doing the coil wiggle,not swing)right right where a target was nulling the threshold.I dug the hole and pulled out a slightly corroded nail,then stuck the DX1 probe in the hole and got my 70s VDI reading.About an inch deeper was my second 1917 wheat from this site.The ground at this site is very hard and dry (comparable to a road that has been chip sealed with rollers).Ive found that with a high recovery setting and the filter setting at 5,the coil can be moved VERY slowly and still pick up a target.I wouldnt even consider the way Im moving the coil a swing.This same method has gotten me very deep and high 80-90s VDI blips at near a foot deep which so far have turned out to be very corroded nails.I believe, but havent tried setting the recovery lower and filter higher that these settings would null the threshold.I also have to believe that if I do get my coil over some silver with the settings Im running I'll know it.I cant imagine picking up these corroded nails at that depth and not having the V signal a good target.I dont dig nulled signals generally,I just tried it to clean up a surface area for an experiment.Finding that wheat in close proximity to the nail gave me the confidence that I can pick up a good target in close proximity to a nulled target.If a person was interested in digging deep nulled targets I would have to think they would have better luck and get more information (maybe) learning thier program in mixed mode.Something I havent been able to do yet.

 

[cloudbuster]

Hi Dave... if the V3 is set in discriniation mode (which most programs are!!!) the VDI numbers that are discriminated against will indeed make the threshold null. This will give the indication that there is a metal object present but you have chosen to discriminate it out. this function will only work in the discrimination mode as if mixed mode or all metal is chosen all vdi numbers will give an audio output according to your audio setup. I dont know where you are but here in the Uk the Non discriminated VDI numbers i would recommend for general use are -25 to +94. Hope this helps.

regards rob

 

[Neil in West Jersey]

Mixed mode will give you the low "hum" of discriminated out targets. This is helpful for a number of reasons. Number one is that it will eliminate nulling. Number two is that you can get an idea of the ID of the target by the pitch and duration of the hum. (VCO must be ON).