If I hold the AT pro with the coil pointing down and twist the detector back and forth it will false with the bell tone in STD mode. If I raise the coil (not straight up but with the detecotor parallel to the ground) while twisting it back and forth the falsing will just about completely quit the higher i go. With the coil pointing up towards the sky it will hardly false at all. This dont make sense. Any ideas why it would not false with the coil pointing upwards. I know its not falsing on something in the ground or near by.