Rover With Moving Baseline; Message Latency - u-blox C94-M8P User Manual

4.3.4 Rover with moving baseline

The Rover will switch automatically to moving baseline mode when receiving RTCM message 4072. Refer to Figure
9 for a configuration flowchart for the default mode.
The following Rover NEO-M8P UART settings are required when operating in the moving baseline mode:

Set to RTCM3 Protocol in and No protocol out.

Set to 19200 baud when using the C94 radio modem at 1Hz moving baseline mode.

The Rover UART baud rate must be the same as the Base UART baud rate.
Figure 15: Configuring Rover UART port
The Rover navigation rate, which is set using UBX-CFG-RATE must match the Base navigation rate. The maximum
rates for wireless and wired modes are:-

Wireless RTCM3 (using C94 radio) =

Wired RTCM3 serial connection (without C94 radio) = 4 Hz, UART at 115200 baud
Figure 16: Configuring Navigation rate

4.3.5 Message Latency

The RTCM communications link must be considered with respect to the data throughput requirements for the
enabled RTCM messages at the specified navigation rate. This is critical for moving baseline operation in which the
message latency from Base to Rover must not exceed 700 ms, otherwise parameter propagation is carried out with
a possibility of reduced accuracy. The Rover will drop out of float/fixed mode if the overall message delay extends
beyond 3 s. The radio link capacity and therefore delay in the Rover receiving messages is affected by the amount of
messages selected and navigation rate used.
A wired RTCM3 connection (if the application warrants it) will be less affected by the baud rate and individual
messages selected. However, there are constraints on the minimum baud rate required to minimise latency.
UBX-15031066 - R07
1 Hz, UART at 19200 baud
Early Production Information
C94-M8P - User Guide
Configuration
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