The video explains how Minelab uses real soil conditions to maximize their detector's performance.
https://www.youtube.com/watch?v=YeCkhUt9ukM
And a bit more explanation from Minelab. http://www.minelab.com/go-minelabbing/treasure-talk/in-the-ground-is-where-detecting-really-counts
https://www.youtube.com/watch?v=YeCkhUt9ukM
And a bit more explanation from Minelab. http://www.minelab.com/go-minelabbing/treasure-talk/in-the-ground-is-where-detecting-really-counts