Dig Every Target. No.

[Tec]

Discrimination using response shape.

[Carl-NC]

IMO, 18-33us is too narrow of a range for this concept. It's like multifrequency, where you want to space the frequencies farther apart to get distinguishing results. I would suggest something like 10,20,40,80, & 160us. This is exactly what I was looking to do with AMX.

[Tec]

Attached are scans 0 to 150uSec in 1uSec increments.

The Target-scans are taken by first scanning without a target (reference scan) and then scanning with a target and subtracting the reference scan.

Note the coil is slightly under damped so there is a hump, The hump doesn't really affect the target signal.

[Carl-NC]

Plot these on a log-linear graph for more interesting results.

[Old cart]

Thanks for the data. These look like they could provide useful results. I specifically like the ratio data. A couple of points.
The underdamped coil could be hurting your data at very short delays, I suggest fixing that. Drop the horseshoe and add a 1cm square of folded tin foil to simulate a small gold ring. Smooth the data over a 5 uS window to eliminate trace “ noise”.

Question, is the data in the text files taken at a 1uS interval? It would be very cool if the detector could take input about the nature of each target as it was dug up. That way, with the right code, it might be able to “ train itself” to be more accurate as it was used.

[Tec]

Ok I will adjust the damping. The data in the file is at 1uSec resolution. 50 samples are averaged. I am also making a 5 inch coil and a 12 inch coil. The 5 inch will be around 300uH and the 12inch will be 420uH unless there is some other ideal value to aim for ..

[Tec]

A small fast (?) coil for fine targets, tested with Aluminium-foil squares.
Shows the effect of damping resistor adjustment