How does surface calibration work?

These words are from Logitech support:
"minthreshold or pixelthreshold affects tracking/scrolling. this means the minimum pixel needed to be traveled by the laser for the cursor to trigger movement. simply put, it affects mouse sensitivity. minsqual affects LOD/lift off distance. this is the distance you can lift the mouse until it stops tracking. these are some advanced settings within the mouse configuration that is not recommended to be changed for the normal user."

Anyway, I still dont know what leddrive variable means (can be set to 0 and to 1, at 1 mouse tracks better on my glass mousepad). And I still dont understand why I can set minsqual (LOD) higher only when I set pixelthreshold (sensitivity) lower and keep tracking. From my understanding LOD (minsqual) and sensivity (pixelthreshold) they seems be unrelated, but they are obviously related somehow.

Actually I think Hero sensor lacks of surface calibration in compare with 3366 just because it is done on the fly at Hero sensor, but maybe I am wrong.