How are angular measurements defined with the IDFS paradigm?
Within the IDFS formalism, any virtual instrument may be assumed to be embedded within an inertial spherical coordinate system. This is a standard spherical coordinate system with the azimuthal angle measured in the XY plane, 0 degrees being along the positive X axis and increasing with rotation into the positive Y axis. The polar angle is measured from the Z-axis, with 0 degrees being along the positive Z-axis. The azimuthal angle varies between 0 and 360 degrees and the polar angle varies between 0 and 180 degrees. If the virtual instrument is in a non-rotating environment, then the axes of the inertial coordinate system can be defined to lie along any preferred direction. If, however, the instrument is within a rotating environment, then the inertial Z axis lies along the angular momentum vector (positive Z pointing in the positive vector direction) and the positive X axis points along a direction which can be identified within the telemetry stream. This direction is located by a de
