u-blox C94-M8P Series User Manual page 12

C94-M8P - User Guide
Survey-in mode
If the coordinates of the Base Station antenna are not known with very good accuracy, the Base Station should
be configured to operate in Survey-in mode. When working in Survey-in mode the Base Station will determine its
own position by building a weighted mean of all valid 3D position solutions.
The UBX-CFG-TMODE3 message has two fields to fill in for survey-in mode, as shown in Figure 5. The first field,
"Minimum Observation Time", defines a minimum amount of observation time regardless of the actual number
of valid fixes that were used for position calculation. Reasonable values range from one day for applications that
require high absolute accuracy, to a few minutes for applications that only require high relative accuracy.
The second field, "Required Position Accuracy", forces the calculated Base station position to be of at least the
given 3D position accuracy.
Navigation Rate (UBX-CFB-RATE) should be 1 Hz during Survey-in.
Figure 5: Configure to Survey-in Mode for a Base Station
In operation, after both requirements are fulfilled, the Base station finishes the Survey-in mode and enters Fixed
mode automatically. Through the UBX-NAV-SVIN message, the Base operation status from Survey-in to Fixed can
be monitored, as shown in Figure 6.
started
UBX-15031066 - R06 Advance Information Getting
Page 12 of 29