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GLONASS x x
Note: only RTCM V3 format differential corrections are supported in gx/ix mode.
The Recovery tab controls how the RT will accept or reject GNSS measurements. The
RT will automatically reject GNSS updates that it believes are not correct. However,
there is a limit on the number of GNSS measurements the RT will reject. Once this limit
has passed the RT will accept the GNSS update since it is possible the GNSS is correct
and the inertial measurements are not. The GNSS control determines how long the RT
should wait before forcing the GNSS to be accepted. Both the velocity and the position
can be controlled separately.
In the default state the RT will reject up to 20 GNSS measurements before it forces the
GNSS to be accepted. However, in high multipath environments, and when wheel speed
is used, it may be desirable to reject more GNSS measurements. Select the Start
believing measurements after option and enter the number of GNSS measurements to
reject before the system starts believing it again.
The RT families have different GNSS receivers in which have different update rates for
position and velocity. Table 35 shows the update rates of the RTs.
Table 35. GNSS update rates
Product family Position Velocity
RT2000 2 Hz 4 Hz
RT3000 2 Hz 10 Hz
RT4000 2 Hz 10 Hz
This means for example, that if you wish an RT3000 to start believing both position and
velocity GNSS measurements after 30 s, the device it should be configured to start
believing measurements after 60 position updates and 300 velocity updates.
Surface tilt
Adjustment: click … button to open properties window.
The surface tilt settings are used to compute the roll, pitch (and heading) compared to a
flat inclined surface. The roll and pitch from the RT products are measured compared to
gravity. Most test tracks are built at an angle so rain water runs off and the track dries
faster. As the vehicle drives up the incline, the pitch shows a positive value; as the vehicle
drives down the incline the pitch shows a negative value; the value changes with a
sinusoidal pattern as you drive round a circle. The roll angle shows a similar effect.
Using the surface tilt option, the roll and pitch compared to the inclined surface can be
output as well. The NAVdisplay software contains a tool for working out the surface
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