FASTRAK MANUAL
Rev. G
D-6
JUNE 2012
reference axis. Elevation is a rotation of the receiver’s
x
axis about the Y reference axis. Roll is a
rotation of the receiver’s
y
(or
z
) axis about its
x
axis.
In order to measure the orientation Static Accuracy in the same manner that the positional
accuracy was obtained, the aforementioned precise gimbal test fixture is required to allow input
of precise and simultaneously different attitudes. As with the positional measurements, azimuth,
elevation, and roll measurements of the receiver are taken in a statistically valid number of
known attitudes in fixed and known locations throughout the same specified motion box as used
for the positional measurements. The azimuth, elevation, and roll error terms are recorded and
the RMS values calculated for each term. The resulting error values (one for azimuth, one for
elevation, and one for roll) are the instrument’s orientational Static Accuracy. As for the
positional Static Accuracy, the overall orientational Static Accuracy for azimuth, elevation, and
roll may be obtained by calculating the RMS value for all orientational Static Accuracy points
taken within the specified field-of-regard.
CONCLUSION
It can be seen from the above discussions that accuracy and resolution for
electromagnetic, 6DOF instruments conform to the classical definitions of these terms. Accuracy
is indeed the fractional error obtained in making a measurement and Resolution is the granularity
of the measurement or the smallest amount of the quantity being measured that the instrument
will detect. It can also be seen that numerical values of accuracy and resolution may be obtained
from careful and precise measurements of the system’s output data with respect to surveyed and
known receiver positions and orientations.