Thanks for the speedy reply. That's why I was asking, as the MARS coils have only the two windings (one Transmit and one Receive). I couldn't see how they could do the imaging with that setup.
The Garrett coils have the three windings (one Transmit, and two Receives). The two Receive coils have different diameters. In effect, we have two "cones" of signals in the ground, of two sizes and depths, coming back to the detector. By comparing the two signals, the GTI gets the target's size as well as its depth and shows that in the imaging.
I looked at the MARS coil advertisements, and didn't see any mention at all of the "imaging" -- either having it or not having it. I think they should have had a statement about that in their ad, as that's one of the main benefits of the GTI. To be fair to them, maybe I missed it.
Let us know how you're getting along with the MARS -- more depth and target accuracy? Is it better in the field, even without target imaging?
Cheers,
Joe