The diffusion of smartphones providing multifrequency GNSS measurements, including carrier phase observations, has opened new opportunities for the achievement of high-accuracy position from low-cost devices. This paper showcases the effectiveness of using GNSS observations from the triple-frequency Huawei P40 Mate smartphone for Real Time Kinematic processing under different environments and dynamic conditions.

Since the quality of the GNSS measurements is affected by the low-quality smartphone antenna, we conducted a preliminary analysis to quantify the antenna impact on the measurements. Survey and patch antennas were connected to the smartphone under open sky/static conditions for comparison purposes. Several key performance indicators were analysed: the signal power, the tracked satellite number, the positioning accuracy, and the percentage of fix solutions using bases at different distances (i.e. 5, 10 and 25 km).

The GNSS measurement quality is enhanced using external antennas, and the signal power is increased by about 8 dB-Hz for GPS L1 and L5 exploiting a survey antenna. However, the paper shows that, even using the smartphone's antenna, about 99% of fix solutions and centimetre positioning accuracy can be achieved by ad hoc tuning the RTK algorithm.

Moreover, a dynamic test was conducted fixing the smartphone to the windshield of a tractor (Figure 1) and two automotive tests were performed in a rural environment with the smartphone fixed to the car's windshield and roof. The smartphone and the reference trajectories (in orange and in green) are reported for the test with the tractor (Figure 2) and for a section of the test with the smartphone inside the car (Figure 3). The RTK tuning was crucial for increasing the fix solutions allowing to the smartphone trajectories to closely follow the reference ones.

This paper will discuss the results obtained by the above tests and the tuning of the RTK algorithm for coping with smartphone measurements.