C94-M8P - User Guide
UBX-15031066 - R06
Advance Information
Getting
started
Page 10 of 29
3.4.2
Base Station configuration
The board that is selected to operate as Base needs to be configured as described below.
Setting up RTCM messages
A Base device needs to allow RTCM messages 1005 (Station coordinates), 1077 (GPS observations), 1087
(GLONASS observations) and 1230 (GLONASS code-phase biases) to go through the UART1 port on the receiver
module. UART1 refers to the connection between the NEO-M8P-2 GNSS module and the UHF radio module on
the application board. To do this, use the UBX-CFG-MSG messages as shown in
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.
RTCM messages should be configured to be output at 1 Hz. The output rate must be the same as the
Navigation Rate of Base station, which is 1 Hz by default.
RTCM messages do not need to be configured differently even if the Navigation Rate of the Rover is
configured differently, e.g. to have a higher output rate than the default 1 Hz.
Individual RTCM messages should be configured at the same rate.
The throughput of the RTCM communications link must be considered with respect to the amount of
bytes required for the enabled RTCM messages and message rates.
RTCM 1230 is required to make GLONASS ambiguity fixing possible.
If BeiDou is used, RTCM message 1127 needs to be used instead of 1087 (GLONASS), and RTCM 1230 can
be omitted.
MSM4 observation messages (i.e. 1074 for GPS, 1084 for GLONASS, and 1124 for BeiDou) can be used
instead of MSM7 to reduce the communication bandwidth requirements.
Figure 2: For a GPS+GLONASS setup, enable the RTCM messages 1005, 1077, 1087 and 1230 on UART1 port
