u-blox C94-M8P User Manual

Also see for C94-M8P: User guide

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C94-M8P - User GuideUBX-15031066 - R07 Early Production Information ConfigurationPage 23 of 474.3.4 Rover with moving baselineThe Rover will switch automatically to moving baseline mode when receiving RTCM message 4072. Refer to Figure9 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 portThe Rover navigation rate, which is set using UBX-CFG-RATE must match the Base navigation rate. The maximumrates for wireless and wired modes are:- Wireless RTCM3 (using C94 radio) = 1 Hz, UART at 19200 baud Wired RTCM3 serial connection (without C94 radio) = 4 Hz, UART at 115200 baudFigure 16: Configuring Navigation rate4.3.5 Message LatencyThe RTCM communications link must be considered with respect to the data throughput requirements for theenabled RTCM messages at the specified navigation rate. This is critical for moving baseline operation in which themessage latency from Base to Rover must not exceed 700 ms, otherwise parameter propagation is carried out witha possibility of reduced accuracy. The Rover will drop out of float/fixed mode if the overall message delay extendsbeyond 3 s. The radio link capacity and therefore delay in the Rover receiving messages is affected by the amount ofmessages selected and navigation rate used.A wired RTCM3 connection (if the application warrants it) will be less affected by the baud rate and individualmessages selected. However, there are constraints on the minimum baud rate required to minimise latency.