The Course interface is used to get the GPS course.
org.freedesktop.Gypsy.Course
Description: Get the GPS course.
Bit mask, gives fields validity.
i: tstampThis is the seconds elapsed since epoch.
d: speedSpeed in knots.
d: headingDirection in decimal degree.
d: climbRate of ascent or descent in knots. The device is descending if value is positive.