Ali Karimidoona, Steffen Schön, Institute für Erdmessung, Leibniz Universität Hannover, Germany

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Abstract:

Network RTK technique provides the most precise absolute solution among any other navigation methods. So, it plays an important role in the increasing world of autonomy. In addition, integrity monitoring is of great importance in autonomous positioning. In this contribution, the performances of different commercial RTK systems are investigated to evaluate the integrity of the N-RTK solution. We conducted a static experiment in a very good sky visibility condition and kinematic experiments in the urban environments of Hannover. Four commercial RTK receivers including a Leica GS18 T, a Trimble R12i, a u-blox ZED-F9P and a Septentrio Altus NR3 were used. For the static part, these receivers were mounted on stationary pillars with very good satellite visibility and gathered N-RTK solution as well as raw observations for half an hour in 10 Hz. These results serve as a reference for more challenging environments in kinematic part. In the next step, the receivers were mounted on the roof top of a van. The van drove, repeating 1 km loop twelve times. In order to understand the positional variations of the N-RTK solutions, some parameters which show the quality of the raw data e.g., number of visible satellites, signal strength, signal continuity and also multipath and Melbourne-Wübbena linear combinations are investigated showing the challenging in urban areas. Also, the highly variable quality of the receiver-internally logged N-RTK solution was assessed using solution type (code, float, fixed), CQ (Coordinate Quality) of the solution calculated by the receiver, horizontal and vertical deviations of the RTK from the reference trajectory obtained from GNSS-IMU highlighting the impact of the variable satellite. The reliability analysis in form of Stanford diagram shows at best around 14% of nominal operation.