## 2 Materials and Methods
### GNSS Data Collections, Pre-Processing, and Quality Check  
The methodology adopted is outlined in Figure 3. GNSS Data was collected through a campaign survey at 11 locations (Figure 4 and Table 3) located in an urban growth area. The survey was carried out in different environments that degrade the GNSS signal, i.e.,  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Station Name** & **Receiver Type** & **Convergence Time** & **Sensitivity** & **Supported Signal** & **Antenna** \\ \hline \multirow{4}{*}{LCDF} & \multirow{4}{*}{ZED-P9P} & RTK \textless{} 10 s acquisition of cold start (24 s), reaction (2 s) & Track \& Nav 167 dBm, Cold Start \(-148\) dBm, Hot Start \(-157\) dBm, Reaction 160 dBm & \begin{tabular}{c} GANN-MB: GPS + \\ GICNASS + GAILLEO \\ + BEIDOU \\ \end{tabular} \\  & & & & & \\ \hline \multirow{4}{*}{LCSF} & \multirow{4}{*}{NV08C-CSM} & \multirow{4}{*}{\
\begin{tabular}{c} Reaction time \textless{} 1 s, hot \\ start \textless{} 3 s, cold start 30 s \\ \end{tabular} } & Tracking and & GPS, GLONASS, Acquisition \(-160\) dBm, cold start \(-143\) dBm & GAILLEO, BEIDOU, SBAS &
\begin{tabular}{c} Tallyman TW4721: \\ GPS + GLONASS + \\ GALILEO + BEIDOU \\ \end{tabular} \\  & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characteristics of the low-cost receivers.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Station Name** & **Receiver Type** & **Convergence Time** & **Sensitivity** & **Supported Signal** & **Antenna** \\ \hline \multirow{4}{*}{EST1-6} & GEOMAX & \multirow{4}{*}{RTK \textless{} 8 s acquisition of cold start (30 s), reaction (8 s)} & Track Acquisitions \(-140\) to \(-  
dense tree cover, buildings, ravines, etc., in the City of Culiacan Sinaloa, Mexico. The main characteristics of the observations are presented in Table 3. Only the GPS constellation is considered because the GC10 geodetic receiver only captures GPS signal. The static relative method needs at least 30/20 min of occupation time for data collections. As a thumb rule, for first 20 km of distance from the continuously operating reference station, 20 min of occupation is required followed by 2 min of additional occupancy for each km. In our analysis, we considered 2 h observations for low cost GNSS receiver and 30 min plus 3 min/km in case of single frequency receivers.  
Figure 4: (**a**,**b**) Example of 3D location of the low cost GNSS Antenna. (**c**) Location GNSS stations occupied in the observation campaigns, located in Culiacán Sinaloa, Mexico.  
Figure 3: Flowchart depicting Methodology adopted.  
The collected GNSS data was analyzed for Quality Check using TEQC program (similar results can be obtained with G-Nut/Anubis software [37; 38]) to determine the degree of affectation of the signal [1; 37; 38], in the urban area [1]. The mean value of the quality checks parameters from TEQC was derived following a standard statistical method. As per IGS guidelines, the multipath effect average (MP) was calculated by the linear combination of carrier phase and pseudorange in L\({}_{1}\) and L\({}_{2}\) in m with recommended values not above 0.30 m in L\({}_{1}\) and L\({}_{2}\)[39]. The integrity (INT) is theoretically calculated considering the complete observations, and the recommended value is \(>\)95% [1]. Cycle slips were calculated from the carrier phase as per the relationship CSR = \(1000/(\text{o}/\text{slips})\)[40; 41]; where \"o/slps\" is the number of observations between cycle slips. Theoretically, the recommended value must be less than 1 per 1000 observations [42]. The signal-to-noise ratio average (SNR) values were considered as \(\geq\)36 dB Hz in L\({}_{1}\) and L\({}_{2}\)[36].