ZED-F9P - Integration manual
The ZED-F9P should receive RTCM corrections matching its GNSS signal configuration to function
optimally. The rover requires both base station observation (MSM4 or MSM7 messages) and
position message (RTCM 1005 or RTCM 1006) in order to attempt ambiguity fixes. The rover will
attempt to provide RTK fixed operation when sufficient number of ambiguities are available. If phase
lock on sufficient number of signals cannot be maintained, the rover will drop back to RTK float
mode. The rover will continue to attempt to resolve carrier ambiguities and revert to RTK fixed mode
once the minimum number of signals has been restored.
The RTK mode that an RTK rover operates in can be configured through the CFG-NAVHPG-
DGNSSMODE configuration item. The two following RTK modes are available:
• RTK fixed: The rover will attempt to fix ambiguities whenever possible.
• RTK float: The rover will estimate the ambiguities as float but will make no attempts at fixing
them.
The time after which RTCM data will be discarded can be configured through the CFG-NAVSPG-
CONSTR_DGNSSTO configuration item.
The received correction messages stream should comply with the following:
• The reference station ID in the reference station message (RTCM 1005 or 1006)) must match
that used in the MSM observation messages. Otherwise, the rover cannot compute its position.
• In order to fix GLONASS ambiguities the correction stream must contain message 1230
or 1033. Otherwise, the carrier ambiguities will be estimated as float even when set to
operate in RTK fixed mode. This will result in degraded performance, especially in challenging
environments.
CFG-RTCM-DF003_IN can be used to configure the desired reference station ID and CFG-RTCM-
DF003_IN_FILTER can be used to configure how strict the filtering should be (RELAXED is the
recommended setting).
3.1.5.4.1 Message output in RTK mode
When operating in RTK rover mode users should take note of the modified information within the
following NMEA and UBX messages:
• NMEA-GGA: The quality field will be 4 for RTK fixed and 5 for RTK float (see NMEA position fix
flags in interface description). The age of differential corrections and base station ID will be set.
• NMEA-GLL, NMEA-VTG: The posMode indicator will be D for RTK float and RTK fixed (see
NMEA position fix flags in interface description).
• NMEA-RMC, NMEA-GNS: The posMode indicator will be F for RTK float and R for RTK fixed (see
NMEA position fix flags in interface description).
• UBX-NAV-PVT: The carrSoln flag will be set to 1 for RTK float and 2 for RTK fixed.
• UBX-NAV-RELPOSNED
• The diffSoln and relPosValid flags will be set
• The carrSoln flag will be set to 1 for RTK float and 2 for RTK fixed
• UBX-NAV-SAT
• The diffCorr flag will be set for satellites with valid RTCM data
• The rtcmCorrUsed, prCorrUsed, and crCorrUsed flags will be set for satellites for which the
RTCM corrections have been applied
• UBX-NAV-SIG
• For signals to which the RTCM corrections have been applied, the correction source will be
set to RTCM3 OSR and the crUsed, prCorrUsed, and crCorrUsed flags will be set
• UBX-NAV-STATUS
• The diffSoln flag and the diffCorr flag will be set
• The carrSoln flag will be set to 1 for RTK float and 2 for RTK fixed
UBX-18010802 - R08
3 Receiver functionality
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Early production information
