## 2 Materials and Methods  
In the first quarter of 2019, a new generation of GNSS receivers entered the market, offering approximately 10 times lower costs compared to geodetic GNSS receivers and antennas. These new devices are multi-frequency (L1 and L2) and multi-system (supporting GPS, GLONASS, Galileo, and BeiDou) GNSS receivers. In this study, the u-Blox ZED-F9P low-cost GNSS receiver and AS-ANT2 BCAL antenna from ArduSimple were employed. The technical features of the receiver and antenna are listed in Table 1 and Table 2, respectively, and Figure 1 displays the U-Blox GNSS receiver and antenna provided by Ardusimple. The calibration parameters of AS-ANT2 BCAL antenna are published by the National Geodetic Survey (NGS) [34]. \begin{table}
\begin{tabular}{l c} \hline \hline
**Technical Features** & **U-Blox GNSS Receiver** \\ \hline GNSS chip & ZED-F9P \\ Constellations & GPS, GLONASS, Galileo, and BeiDou \\ Frequencies & L1/L2 \\ Signals & L1C/A, L1 OF, E1, B1I, L2C, L2 OF, E5b, and B2I \\ Channels & 184 \\ Weight & 19.5 g \\ Size & 69 mm 53 mm \\ Ports & 5 \\ Messages & UBX, NMEA, and RTCM3 \\ Supply voltage range & 4.5–5.5 V \\ Supply current & 80 mA \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical features of U-Blox GNSS receiver. The data collection with the Ublox GNSS receiver was conducted using the u-center software (v22.02) developed by Ublox. The receiver was connected to the laptop, where the USB port was used for power supply as well as for data storage. The u-center software was installed on a laptop computer, which remained connected to the GNSS receiver throughout this study. GNSS data are collected in UBX format using the GNSS receivers. The GNSS data in UBX format can be converted to Rinex format using RTKCONV, a module of the RTKLIB software (2.4.2) [35]. Throughout this study, raw GNSS data in UBX format was converted to Rinex format using the RTKCONV software (2.4.2), resulting in 24 h data files. In the scope of this study, test measurements were conducted on the rooftop of the Faculty of Civil Engineering at Yildiz Technical University, specifically at the pillar named UZEL (Figure 2). At the UZEL GNSS station, there is an electrical panel that can be powered from the city power grid, and at the same time, with the help of solar panels, batteries, and other equipment, the system can operate uninterrupted with its own generated energy when it cannot receive electricity from the city power grid. The AS-ANT2 BCAL low-cost GNSS antenna was mounted on the Zeiss BRT 006 basis-reduktionstachymeter, and GNSS measurements were carried out over a period of 10 days (Figure 3). \begin{table}
\begin{tabular}{l c} \hline
**Technical Features** & **AS-ANT2 BCAL Antenna** \\ \hline \multirow{7}{*}{Supported positioning signal bands} & GPS: L1, L2 \\  & GLONASS: G1, G2 \\  & BeiDou: B1, B2 \\  & Galileo: E1, E5b \\  & QZSS: L1, L2 \\  & SBAS: WAAS, EGNOS, MSAS, and GAGAN \\ Polarization & RHCP \\ Peak gain & 5 dBi \\ Axial Ratio @ zenith & \textless{}3 dB \\ Azimuth coverage & 360 degrees \\ Impedance & 50 ohm \\ Phase center error & \(\pm 1\) mm \\ Maximum length & 152 nm \\ Weight & 400 g \\ Mounting style & Magnetic base or \(5/8^{\prime\prime}\times 11\)TPI thread \\ Connector & TNC female \\ \hline \end{tabular}
\end{table} 
Table 2: Technical features of AS-ANT2 BCAL antenna. Figure 1: Low-cost GNSS receiver (U-Blox ZED-F9P and AS-ANT2 BCAL antenna). The Zeiss BRT 006 basis-reuktionstachymeter allows for the measurement of horizontal directions, zenith distances, and lengths, as illustrated in Figure 4. Notably, it features optical distance measurement capabilities. The parallactic triangle, characterized by a fixed parallactic angle and a variable base at the station point, is rectangular. The prism, ensuring a constant angle, moves along the metal guide through a division. In the eyepiece, observers see a double image of the target point, one direct and the other provided by the moving prism. The prism is adjusted until the two images coincide.