discrimination

[tometusns]

How do you determine how many segments a machine that gives you a numerical readout has. The more segments the more diversity you have (two objects could have the same readout in 14 segment but in 28 segments they are now identified as two different objects. On a 0 to 99 scale do all objects read different or are they still lumped together like the segments. Just wondering a little about how things work. Thanks!

 

[mrwilburino]

Operating frequency would play a big part on where a particular object would read on the VDI. Of course it would also depend on how the manufacturer has the machine set up. Here's a good example using the four different frequencies of the Deus:

 

[WV62]

I have only used Fisher, White's and Tesoro machines, so I don't know about disc on on other brands. But the none of the machines I have ever used have the disc divided up in to segments. Maybe I am not understanding your question, the chart above looks to be giving a range of numbers that a object may give on the ID screen. When I think of a segment that sounds like if you set the disc to a number it will take in several other numbers. All the machines I have ever used with ID numbers the disc is always up to that number. For example if I set the disc to 51 everything below 51 and 51 is disc out.

Now if you were talking notches they will take in several numbers (segment) when set. So my machine if I set a notch it will be 5 numbers.

Sorry if I am off track to your question. Maybe if you posted what machine you are talking about somebody could jump right in with a good answer.

Ron in WV

 

[Elton]

Discrimination range


OBJECT TARGET I.D.
Most iron objects 4-12
foil from gum wrapper 16-25
U.S. nickel (5

 

[MarkCZ]

Well the more segments on the graft the more refined the ID should be! (I'm thinking of like a bar graft with segmented bars) the same thing applies to a numbered system. if the detector only has a range of 0-50 and that includes all iron then each object (target) has to be defined within that range, but if the unit uses 0-99 then the range should be more refined. Its very rare for a target in the ground to hit solid on only one number, they almost always have a range they jump a little, so a US quarter's ID maybe be 30, but in the ground it may jump from a 28 to 32, closer to the coil and out of the ground that range will tighten up to a more solid reading of 30. That number isn't universal between models or brands, its just one that I took from one of my units.

So, no! a copper penny may hit at 28, but a nicked one or one that has a bit of it clipped off from maybe a lawnmower would drop to a slightly lower number, like maybe 25 or 26, two pennies together would raise the penny ID somewhat to maybe 29-30 but it wouldn't double it.
A numbered ID system doesn't use a "Block" ID system, now if the unit has a "Notch" feature then each notch is more of a "Block" or range as Elton's chart above shows, but the target ID number still scales number by number through each notch. (Notch is an added feature besides the target ID scale)

Mark

 

[tometusns]

I had a 705 and it had 28 segments verses a smaller amount on the 505 and 305. So I figured more objects would fall in a segment of a machine with fewer segments. Just thinking that you could get the same numbers for two different targets when with more segments the machine might be able to separate the targets better. So a machine that has a 0 to 99 readout...does it have the ability to read all targets differently or is there something in the discriminating ability of even machines that have a higher vdi scale. Will a less expensive machine 0 to 99 be able to separate like a higher end 0 to 99 scale machine and if not then are there not segments or notches in the discrimination of these machines as well. I just really want to learn more about the hows and whys of metal detecting. Thanks, Tom

 

[MarkCZ]

I had a 705 and it had 28 segments verses a smaller amount on the 505 and 305. So I figured more objects would fall in a segment of a machine with fewer segments. Just thinking that you could get the same numbers for two different targets when with more segments the machine might be able to separate the targets better. So a machine that has a 0 to 99 readout...does it have the ability to read all targets differently or is there something in the discriminating ability of even machines that have a higher vdi scale. Will a less expensive machine 0 to 99 be able to separate like a higher end 0 to 99 scale machine and if not then are there not segments or notches in the discrimination of these machines as well. I just really want to learn more about the hows and whys of metal detecting. Thanks, Tom

Your correct! if the machine only has two segments (none have that few I know) then all targets would have to fall into those two segments, up that to 50 segments, or 99 and the ID range per target increases.

The better the machine the better it should ID, in other words, a $100.00 dollar machine that has a VDI range of 0-99 may not ID as well as a $1000.00 machine with the same ID range (in theory anyway).

Different machines will do things a little differently, take my Fisher Coinstrike, the target ID system is all metal! it reads everything all the time regardless of any settings, so in that case the discrimination control is only functioning on the audio response. But on others as you run the discrimination up, the target ID will stop displaying information below the disc set value. Now, with a unit that has a notch function you can run the discrimination up to max, then go back and disc in any one of the notches (blocks) back in. Something like this,
Run the discrimination up to just below pennies,
then go back and notch in the nickel range.
What happens here is the ID meter will not display anything up to below the nickel range,
then it will display all targets in the nickel range,
then it will skip everything between nickels and copper pennies and then it will display everything above the pennies.

Now with most units that has the notch feature you can work the reverse of the above and notch out the different blocks, so you can notch in, or notch out the blocks.

Now, keep in mind that these ID meters get fooled a lot! most of them work near perfect doing air test, but in the field they are not as reliable, many times its those hints to a good target that will cause us to dig them and the deeper the target the ID reliability tends to drop. Its these times when it takes knowing your machine and what its trying to tell you do really get the best out of any detector.

Mark

 

[tometusns]

Thanks for the replys,Tom

 

[Spider-F5]

very good information guys. certainly helped clear a few things up for me. thanks a million.