ZED-F9P - Integration manual
• The RTCM 3.3 stream must contain reference station message 4072.0 (position information)
and MSM4 or MSM7 observation messages, otherwise the rover will be unable to operate in MB
rover mode.
• Message 4072.1 (timing information) is no longer necessary for moving base rover and as such
it is no longer used by a moving base rover. To reduce the bandwidth requirements between a
moving base rover and a moving base, it is recommended to disable RTCM 4072.1 output on
the base.
• Message 4072.0 must be sent for each epoch the MB base observations are sent.
• To ensure that the moving base processing works, the MB base and rover must use the same
navigation update rate and measurement rate.
The desired RTCM messages must be selected and configured for the corresponding GNSS
constellations received. The recommended list of RTCM output messages for a base operating in
MB configuration are:
• RTCM 4072.0 Reference station PVT information
• RTCM 1074 GPS MSM4
• RTCM 1084 GLONASS MSM4
• RTCM 1094 Galileo MSM4
• RTCM 1124 BeiDou MSM4
• RTCM 1230 GLONASS code-phase biases
Additionally, while an MB receiver operates as a base, it is able to simultaneously:
• Apply RTCM 3.3 corrections and reach RTK fixed mode.
• Generate an MB correction stream for accompanying MB rover(s).
3.1.5.6.2 Rover operation in MB RTK mode
While the MB RTK solution aims at estimating the relative position with centimeter-level accuracy,
the absolute position of each receiver is expected to be known with a standard GNSS accuracy of a
few meters, unless the base is receiving RTCM 3.3 corrections.
In addition to the rules described in the rover operation section, the following moving base specific
rules apply:
• A moving base receiver typically experiences worse GNSS tracking than a static base receiver in
an open-sky environment and therefore the MB RTK performance may be degraded.
• The MB rover will wait as long as possible to compute a navigation solution, possibly lowering
the navigation rate all the way to 1 Hz while doing so. If not time-matched observations are
received in time, the receiver will flag the relative position as invalid.
• The achievable navigation update rate of the MB RTK solution is limited by the communication
link latency. Latency here refers to the delay we have in getting the RTCM messages on the
rover from the time they are sent from the base station.
• It is a good idea to try and minimize the latency in the communication link, especially if trying to
achieve high navigation update rate. As a rule of thumb, the communication link latency should
be less than the desired navigation update period minus 50 ms.
• If the communication link latency is too high to achieve the configured navigation update rate
the receiver will lower the navigation update rate until it reaches 1 Hz.
• If the communication link latency is too high for 1 Hz rover operation, the receiver will declare
the relative position as invalid.
• To ensure that the moving base processing works, the MB base and rover must use the same
navigation update rate and measurement rate.
In addition to the modified output described in the rover operation section, the following moving
base output message modifications will be observed:
UBX-18010802 - R08
3 Receiver functionality
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Early production information
