ZED-F9P-Integration Manual
UBX-18010802 - R02
3 Getting started Page 16 of 114
Advance Information
3.5.1.3 Survey-in
Survey-in is the procedure that is carried out prior to using Time Mode. It determines a stationary
receiver's position by building a weighted mean of all valid 3D position solutions.
Two requirements for stopping the procedure must be specified:
• The minimum observation time defines a minimum amount of observation time regardless of the
actual number of valid fixes that were used for the position calculation. Reasonable values range
from one day for high accuracy requirements to a few minutes for coarse position determination.
• The required 3D position standard deviation defines a limit on the spread of positions that
contribute to the calculated mean.
Survey-in ends, when both requirements are met. After Survey-in has finished successfully, the
receiver will automatically enter fixed position Time Mode.
The Survey-in status can be queried using the UBX-NAV-SVIN message:
• The "Standard Deviation" parameter defines uncertainty of the manually provided "True Position"
set of parameters. This uncertainty directly affects the rover absolute position accuracy. This is
to prevent an error that would otherwise be present in the rover absolute position because of the
initially inaccurate position (assumed to be correct by the receiver) without users being aware
of it. The "3D accuracy" parameter in "Fixed Position" as well as the "Position accuracy limit" in
"Survey-in" affect the produced rover absolute position accuracy in the same way. Note that the
availability of the position accuracy does not mitigate the error in the rover position, but only
accounts for it when calculating the resulting positioning accuracy.
3.5.2 Required configuration of the base and rover
This section describes how to configure the base station and the rover in detail.
3.5.2.1 Base station configuration
Base Station receiver mode is where the receiver makes measurements of all available satellites to
broadcast corrections. Configuring a stationary base station is done in two steps:
• The receiver must be set in Time Mode using the configuration steps described in the Time Mode
Configuration section (CFG-TMODE-MODE).
• The RTCM 3x correction stream must be configured following the rules detailed in the Base
station: RTCM output configuration section. Each RTCM message must be individually enabled
using CFG-MSGOUT-* configuration group.
By default the base station will begin operation in standard GNSS mode without any RTCM output.
Messages for observations will be streamed as soon as they are configured for output. However
messages for the base station position will only be output when both the base station is in
fixed position mode, and the message is configured for output. As explained in the Time Mode
Configuration section, this mode can be directly configured or reached at the end of a successful
survey-in.
The rover will need to have received both base station observation messages and base station
position messages in order to attempt ambiguity fixes.
3.5.2.2 Rover configuration
The RTK rover can be configured to work in either of these two differential modes using
configuration item CFG-NAVHPG-DGNSSMODE:
• RTK fixed: In this mode, the rover will attempt to fix ambiguities whenever possible.
• RTK float: In this mode, the rover will estimate the ambiguities as float but will make no attempts
at fixing them.
To Next Page
Loading...
Need help?
General
