## 2 Materials and Methods
### MMS POS/LV and GNSS Receivers Used in the Study  
The antennas of the receivers were located at various positions on the iron shaft mounted on the roof and axial to the vehicle, thus making it easy to measure the horizontal distances between them. They served as a reference for the evaluation positioning results (Figures 2 and 3). Figure 1: (**a**) The MMS of the GeoSnav Lab vehicle, University of Trieste, with the GNSS antennas mounted on the roof; (**b**) the setup of the instruments inside the vehicle. Figure 3: The setup of the Trimble antennas of the MMS (at the front and rear of the vehicle), Septentrio PolaNt-x MF multi-frequency GNSS antenna, Xiaomi Mi8 smartphone and low-cost antennas ANN-MB-00 from ZED-F9P and ZED-F9R with the horizontal distances. Figure 2: The setup of GNSS antennas, u-bloves and smartphone on the roof of the vehicle. As shown in Figure 2, the central element of the Applanix system, the PCS (POS Computer System), which can process data from various sensors for real-time positioning and stores the data for post-processing analyses (as in the case in the current study), is in the vehicle. The integrated inertial system is a Littton LN-200 Inertial Measurements Unit (IMU) with three accelerometers and three solid-state fibre-optic gyros (Northrop Grumman, Falls Church, VA, USA). Two Trimble Zephyr GPS antennas are mounted on the car roof and connected to two different BD950 GPS cards in the PCS of the Applanix system. The rear antenna is GPS L1/L2 and is used for positioning; the front is GPS L1 and is used for attitude determination. Trimble's geodetic receivers send positioning and heading data to the PCS, the latter using GAMS (GPS Azimuth Measurement Subsystem). By using a carrier-phase double-difference algorithm to measure the relative position vector between the two antennas, GAMS calibrates IMU and ensures that the azimuth does not drift (when GPS/GNSS coverage exists). During the survey, data from the GPS receivers had an acquisition rate of 1 Hz, while the inertial system sent data to the CPU system at a rate of 200 Hz. The integrated measurements from each sensor were processed using the Kalman filter. In addition to the Applanix professional system, two SimpleRTK2B boards (Ardusimple, Lleida, Spain) were used for this research, one with a ZED-F9P receiver and the other with a ZED-F9R. The boards were connected to a laptop to provide power to both panels and to store the kinematic observations. The reason for storing the observations directly on the computer with the installed open-source programme from U-Center [44] rather than on the SD card was that based on previous experiments, the memory unit was often overloaded when performing measurements in multi-constellations, thus resulting in gaps in the measurements. The two boards and the laptop were inside the vehicle next to the Applanix system components. Two low-cost antennas ANN-MB-00 were mounted on the roof of the vehicle on a special iron structure already used for GPS Trimble antennas and the Septentrio PolaNt-x antenna (Figure 3). Another device, the Xiaomi Mi8 smartphone, was mounted parallel to the roof of the vehicle (Figure 1) in the direction of travel. The smart device was in a specially made plastic box so that it was safe, protected and fixed during the measurements. The duty cycle mode was turned off in the smartphone settings because it determines the time the GNSS chip is actively tracking signals and can affect the quality of the GNSS data. This is because the longer the duty cycle, the better the quality of the GNSS observation. ### MMS POS/LV and GNSS Receivers Used in the Study  
The kinematic tests were conducted on 11 February 2022 in the city centre of Trieste, Italy, and on the outskirts of the nearby region. The measurements in the city were performed only a few metres above sea level, while for the non-urban area, the measurements were taken on a Karst plateau at an altitude of about 350 metres (Figure 4).