Green. Power applied to system
Orange. Trafc present on Ethernet
Red ash. The operating system has
booted but the GNSS receiver has
not yet output a valid time, position,
or velocity
Orange. The INS has initialised and
data is being output, but the system
is not yet real-time
Green. The INS is running and the
system is real-time
Red and green ash. The system is
asleep. Contact OxTS support for
further information
Red. The GNSS receiver has a
differential heading lock
Orange. The GNSS receiver has a
oating (poor) calibrated heading
lock
Green. The GNSS receiver has an
integer (good calibrated heading
lock
Red ash. The GNSS receiver is
active but has not yet determined
heading
LED states
Power
Status
GNSS
Red.The GNSS receiver has locked-
on to satellites and has adjusted
it’s clock to valid (1 PPS output now
valid). The INS is ready to initialise
Key PointsKey Points
Key considerations
/Excitation of the IMU sensors is the essential
requirement of a warm-up. To encourage optimum
performance, the warm-up should be performed in a
similar style as the survey but with more manoeuvres
(without saturating). This is needed for the Kalman lter
to make the correct decisions for scaling the sensor
output during the survey.
/If the Kalman lter has not experienced dynamics of
a certain type before, the output is likely to be scaled
incorrectly as it estimates what the scaling should be. It
is unlikely to estimate perfectly at the
rst attempt.
Why warm up?
/ Georeferencing requires accurate time, position
and orientation.
/ To achieve accurate output of these measurements, the
xNAV Kalman lter monitors states of:
1. GNSS antenna position
2. GNSS antenna orientation (dual antenna)
3. IMU sensor scale factor and biases
4. Live position and velocity errors
/ As a result, the raw data provided by the GNSS receiver
and IMU needs to provide a varied range of data to give
the best opportunity to improve all those states.
