# Data Collection in Areas without Infrastructure Using LoRa Technology and a Quadrotor
## 4 Instrumentation and Construction
### Construction  
Concerning the construction of the prototype, this work does not address the design and structural assembly of the monitoring station or the aircraft; it only focuses on the interconnection of the devices to carry out the data collection and transmission process, which is achieved by flying the UAV at a height of 30 m and a radius of less than 690 m from direct LoS to the custer (monitoring station) [27]. To do this, we divided the system into two modules: the first focuses on assembling devices in the stations, while the second focuses on connecting components required for data collection with the UAV.  
The construction process of the stations is as follows:  
* A container was selected to place the sensors, ensuring that the electronics were kept isolated from water.
* The conductivity and dissolved oxygen sensors were calibrated, as indicated in the product specification manuals.
* The sensors were installed to be in direct contact with the water.
* The additional components (Raspberry Pi 4, transmission module, and battery) were placed, taking care that they were kept isolated from water.
* The corresponding connection was made on the embedded board of the communication buses with their respective modules and sensors. The dissolved oxygen, conductivity, and turbidity sensors require an ADC converter and a logic converter to connect with the Raspberry Pi 4 through I2C protocol; the temperature sensor requires one-wire communication and the data transfer with the transceiver is performed with the serial protocol (see Figure 5b).  
Similarly, the devices were assembled and connected to the UAV for data collection.
* The devices shown in Figure 4b were placed on top of the UAV structure.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Designator** & **Component** & **Number** \\ \hline Raspberry & RPI4-MODBP & 2 \\ Pi 4 & 8 GB & \\ Raspberry & RPI ZERO- & 1 \\ Pi Zero & W-V2 & \\ Mavic & Mavic Air & 1 \\ Air 2 & 2 & \\ REYAX & REYAX & 2 \\ RYLR896 & RYLR896 & \\ Temperature & DS18B20 & 2 \\ Sensor & & \\ Turbidity & SEN0189 & 2 \\ Sensor & & \\ Conductivity & SEN0451 & 2 \\ Sensor & & \\ Dissolved & SEN0237 & 2 \\ Oxygen & -A & \\ Sensor & & \\ Logic & BSS138 & 2 \\ Converter & & \\ ADC & ADS1015 & 2 \\ converter & & \\ L7805 & L7805 & 1 \\ regulator & & \\ LiPo & Turnigy & \\ Battery & Nano-Tech & 1 \\  & 500 mAh & \\  & 2S & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Bill of materials.  
* The required connections were made between the embedded board, the communication buses, and the modules (see Figure 4b).
* The required connection was made to power the embedded board with the battery through the L7805 regulator.  
It is worth mentioning that the data collection system used is independent of the UAV navigation system; that is, the manufacturing electronics of the UAV are not modified. The collection system continually waits for a signal indicating the information's feasibility. Finally, the assembled systems are shown in Figure 5a,b.  
Note: It is important to mention that monitoring stations are mainly used to validate measurement, packaging, and data transmission, and only the sensors are immersed in water. This system could be improved with future implementation on a real buoy.  
Figure 5: Monitoring system prototype. (**a**) Monitoring system connection. (**b**) Monitoring system connection diagram.