RCB-F9T - Integration manual
The internal filter gain is computed as a function of speed. Therefore, the level as defined in
the CFG-ODO-VELLPGAIN configuration item defines the nominal filtering level for speeds
below 5 m/s.
3.1.8.3.2 Course over ground low-pass filter
The CFG-ODO-OUTLPCOG configuration item offers the possibility to activate a course over ground
low-pass filter when the speed is below 8 m/s. The output of the course over ground (also named
heading of motion 2D) low-pass filter is published in the UBX-NAV-PVT message (
headMot
field),
UBX-NAV-VELNED message (
heading
field), NMEA-RMC message (
cog
field) and NMEA-VTG
message (
cogt
field). The filtering level can be set via the CFG-ODO-COGLPGAIN configuration item
and must be comprised between 0 (heavy low-pass filtering) and 255 (weak low-pass filtering).
The filtering level as defined in the CFG-ODO-COGLPGAIN configuration item defines the
filter gain for speeds below 8 m/s. If the speed is higher than 8 m/s, no course over ground
low-pass filtering is performed.
3.1.8.3.3 Low-speed course over ground filter
The CFG-ODO-USE_COG activates this feature and the CFG-ODO-COGMAXSPEED, CFG-ODO-
COGMAXPOSACC configuration items offer the possibility to configure a low-speed course over
ground filter (also named heading of motion 2D). This filter derives the course over ground from
position at very low speed. The output of the low-speed course over ground filter is published in the
UBX-NAV-PVT message (
headMot
field), UBX-NAV-VELNED message (
heading
field), NMEA-RMC
message (
cog
field) and NMEA-VTG message (
cogt
field). If the low-speed course over ground filter
is not configured, then the course over ground is computed as described in section
.
3.1.8.4 Static hold
Static hold mode allows the navigation algorithms to decrease the noise in the position output when
the velocity is below a pre-defined "Static Hold Threshold". This reduces the position wander caused
by environmental factors such as multi-path and improves position accuracy especially in stationary
applications. By default, static hold mode is disabled.
If the speed drops below the defined "Static Hold Threshold", the static hold mode will be activated.
Once static hold mode has been entered, the position output is kept static and the velocity is set to
zero until there is evidence of movement again. Such evidence can be velocity, acceleration, changes
of the valid flag (e.g. position accuracy estimate exceeding the position accuracy mask, see also
section
), position displacement, etc.
The CFG-MOT-GNSSDIST_THRS configuration item additionally allows for configuration of
distance threshold. If the estimated position is farther away from the static hold position than this
threshold, static mode will be quit. The CFG-MOT-GNSSSPEED_THRS configuration item allows you
to set a speed that the static hold will release.
UBX-22004121 - R01
3 Receiver functionality
Page 17 of 64
C1-Public
Early production information
