Angelic Storm said:
So, let me get this right..... of the 1750 possible FE / CO combinations, the CTX parameters assign FE / CO numbers to what would otherwise be different numbers if it were not for the parameters? Simply put..... Something like titanium would be assigned 12-48/1-48 (not that I have tested it) when otherwise it would have been assigned something like 3-34/4-36/5-35 (just a hypothetical idea of numbers it might read as without the parameters) or did you mean there would have to be more FE / CO numbers to individualize the representation of the metals?
What I meant is...... there are 1750 possible FE/CO combinations available for TID on the CTX. This is due to having 35 different FE numbers, and 50 different CO numbers. The total possible combination would be 35 X 50 = 1750. The more ferrous the target, the larger the first number will be. The more CO (inductance and conductivity) the target has, the larger the second number will be.
In actuality, the CTX processes the response signal coming back from each target using algorithms. Then, through software, each target value is placed on an electronic graph. To help make this more clear, think of the SmartScreen as that graph. Then think of the numbering system used for assigning TID values as individual boxes on that graph. 35 rows up and down......50 rows across. The placement of a target signal on that graph now has a direct correlation to a set of numbers. And we call those numbers the FE and CO values. As the FE properties increase, so does the FE number. As CO properties increase, so does the CO number. But only due to being placed in a different location on the "graph".
With that in mind......the numbering system for the CTX, as well as every other detector out there, are "made up" numbers. By that I mean they represent a scale of numbers, developed by engineering, to help the user sort out and identify targets for that specific model of detector. They could have named them anything. But using numbers give more flexibility and are more easily "translated" by the user. Andy Sabisch explains this very well in his Explorer and E-TRAC Handbook. If you have an opportunity to read the book, even though it isn't written for the CTX, you will have a better understanding of how Minelab engineered the TID functionality in their FBS units.
As far as one number representing a specific target.... nope! Here is an old chart that I've "borrowed" from one of my favorite books....."Taking a Closer Look at Metal Detector Discrimination" by Robert C. Brockett. If you can still find this book anywhere, buy a copy. The chart is based on an old analog meter that reads CO numbers from 1 - 100, instead of 1 - 50 like the CTX. Even though we are now dealing with digital numbers instead of a meter, the theory is the same. The point is, note how many different types of targets are within the same range of CO numbers. You could get a target that read 12 / 35, and expect to dig an Indian penny. But with those FE and CO numbers, you might just pull out a $10 gold piece or a silver half dime. Again, the detector doesn't know what the target is. It can only assess the FE and CO values, and spot the target on the graph. Then that placement correlates to a set of FE and CO numbers. Targets on edge, varying levels of mineralization, too much Sensitivity, soil conditions, adjacent target interference, EMF / RFI......all of these can skew the information provided by the target, thus skew the numbers.
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I might check that book out. Nothing wrong with gaining a little more helpful knowledge. Completely understanding a detector such as the CTX 3030 or rather any other will more than likely help produce better results and give one ideas for improvement although this is an excellent detector. 