RTK Feasibility Analysis for GNSS Snapshot Positioning

With snapshot positioning becoming popular for various applications, the present contribution focuses on the feasibility of achieving Real Time Kinematics (RTK) positioning using snapshot data, i.e. a very brief interval of the received satellite signal. This method is termed as Snapshot RTK (SRTK). We first introduce the general workflow of snapshot positioning and the SRTK engine functioning blocks. Their differences from traditional receivers and challenges brought by the short duration of data are explained. Since a major difference of this positioning method is the generation of code and carrier-phase GNSS observables, we go through this procedure in details. In order to explore the feasibility of achieving RTK under different scenarios, the rate of Integer Ambiguity Resolution (IAR) is assessed by using snapshot measurements generated with different integration times and signal bandwidths under zero-baseline configuration. Under these assumptions, the key factor that influences the RTK fix rate is the code measurement noise. Double Difference (DD) code measurement errors are evaluated and plotted together with the resulting IAR fix rates in order to find the relationship between them. The performance of using multi-constellation and multi-frequency signals is tested as well. The fix rate can reach 100% when multiple constellations are used. The achieved positioning accuracy is shown to be less than 5 mm in horizontal domain when IAR is achieved successfully. Finally, some conclusions and thoughts about future research steps on SRTK are given.