Critterhunter
New member
In the past I've always loved reading (or doing my own) pretty extensive testing of coils (or machines) head to head on undug targets in the field. I remember one such way some coils were tested in a thread on undug targets and thought it was the best way to truly contrast the performance aspects of the two coils.
Some people will grid a site with one coil and dig everything they feel worthy of taking a chance on, and then later will come back and grid the same spot using another coil to see if it finds anything more. While that can be informative in certain ways, how are you going to know if the second coil used would have missed what the first one got, or that you missed by accident a target with the first coil that you later found with the second? Even variables like how wet or dry the ground was that day, how high your sensitivity was able to run due to EMI from one day to the next, or something as simple as a slight angle change in your grid pattern or even your attitude for that day could make a difference.
While the above method still can be informative, I feel the best way to compare two coils is to compare them on the same undug targets on the same day. Grid an area with the first coil and lay numbered poker chips on all potentially "good" targets you find and record the response from various angles on a note pad. Next grid the same small area from the same direction using the second coil and once again mark all potential good targets found with numbered poker chips too, recording which coil found which poker chip #, response quality from various angles, and so on.
Then re-check all marked targets with both coils. Note which ones were found first by what coil and to see if the other coil just missed the targets by accident or if that coil simply can't see the target, or perhaps just didn't give a good enough response and so wasn't marked while it did give a good enough hit with the other coil to be deemed worthy to mark for digging. Once all the targets have been cross checked and the responses recorded from each coil from the EXACT same angles, dig'em up and record what each target was and whether it was deep, masked, or on edge.
I wish more people would do this. I see a lot of people have the impression of one coil (or even a machine) doing a better job than an other simply because they went back to a site and found targets with it that they missed the first time. While there is some merit to that, there are just too many variables at play to know for certain. Only head to head testing on undug marked targets found by both coils gridding the same small area are going to illustrate any potential differences in performance, and even then you have to be careful about angles of sweep and doing it on the same day so all ground and EMI conditions are of equal nature. And, that's why it's important to grid the area with both coils and not just re-check targets with the other. There might very well be some coins one coil will see but the other has trouble with, but the reverse of that can also be true for say a coin masked a different way or on edge at a different angle or something. Same deal with depth.
Some people will grid a site with one coil and dig everything they feel worthy of taking a chance on, and then later will come back and grid the same spot using another coil to see if it finds anything more. While that can be informative in certain ways, how are you going to know if the second coil used would have missed what the first one got, or that you missed by accident a target with the first coil that you later found with the second? Even variables like how wet or dry the ground was that day, how high your sensitivity was able to run due to EMI from one day to the next, or something as simple as a slight angle change in your grid pattern or even your attitude for that day could make a difference.
While the above method still can be informative, I feel the best way to compare two coils is to compare them on the same undug targets on the same day. Grid an area with the first coil and lay numbered poker chips on all potentially "good" targets you find and record the response from various angles on a note pad. Next grid the same small area from the same direction using the second coil and once again mark all potential good targets found with numbered poker chips too, recording which coil found which poker chip #, response quality from various angles, and so on.
Then re-check all marked targets with both coils. Note which ones were found first by what coil and to see if the other coil just missed the targets by accident or if that coil simply can't see the target, or perhaps just didn't give a good enough response and so wasn't marked while it did give a good enough hit with the other coil to be deemed worthy to mark for digging. Once all the targets have been cross checked and the responses recorded from each coil from the EXACT same angles, dig'em up and record what each target was and whether it was deep, masked, or on edge.
I wish more people would do this. I see a lot of people have the impression of one coil (or even a machine) doing a better job than an other simply because they went back to a site and found targets with it that they missed the first time. While there is some merit to that, there are just too many variables at play to know for certain. Only head to head testing on undug marked targets found by both coils gridding the same small area are going to illustrate any potential differences in performance, and even then you have to be careful about angles of sweep and doing it on the same day so all ground and EMI conditions are of equal nature. And, that's why it's important to grid the area with both coils and not just re-check targets with the other. There might very well be some coins one coil will see but the other has trouble with, but the reverse of that can also be true for say a coin masked a different way or on edge at a different angle or something. Same deal with depth.