Network Real-Time Kinematic Performance Analysis Using Rtcm 3.0 and the Southern Alberta Network

The RTCM 3.0 data transmission format is introduced and described as it applies to multiple reference station real-time kinematic differential GPS positioning, or network RTK. The new format provides a more modern and flexible message structure that accommodates network RTK data transmission, while requiring up to 80% less bandwidth for the transmission of RTK correction messages. Based on this reduced bandwidth, we investigated moving the correction interpolation step of the network RTK procedure from the network to the rover user. The RTCM 3.0 format is implemented and tested in both network and user software. Three interpolation methods are implemented and compared with single baseline processing using real data collected using reference stations from the Southern Alberta Network. Under moderate ionospheric conditions, the network RTK solution outperforms the single baseline approach in both the observation and position domains. The three interpolation methods are found to be comparable. Under severe ionospheric conditions, network ambiguity resolution becomes difficult, making the network corrections unreliable. It is recommended that a network ambiguity resolution status flag be added to the RTCM 3.0 network correction message format to alert users when network corrections are unreliable.