## 3 Prototype Description and Implementation
### Prototyping of Hardware Components
Due to the importance of this subsystem, it has been further divided onto four different hardware components:  
1. FPV camera (25 \(\times\) 25 mm 1200 TVL CMOS 3.6 mm) [36]: the FPV camera is a small analog video camera placed on the UAV. Its main function is to offer the pilot a real-time image of the position and the environment where the aircraft is located. The video quality must be good enough to allow the operator to maneuver with and steer the vehicle. This component is directly connected to the video transmitter through a bus that feeds the component with power and in turn transmits the signal of the captured image. 2. Video Transmitter AKK-FX2-Dominator 250 mW [37]: it is a component responsible for transmitting the signal it receives from the FPV camera to the receiving CGS. This video transmitter must broadcast a signal with enough power to be received within the radius of action of the flight plan, thus preventing the operator from losing visual reference to the position of the vehicle. Due to the nature of the proposed system, a long-range analog video transmitter has been chosen (the distances handled in the grazing and monitoring of sheep must be considered here). Specifically, this video transmitter offers a range slightly greater than four kilometers as long as it is used with omnidirectional antennas. Taking into account its characteristics and the fact that the area where it will be used does not have major obstacles that could cause interference, it becomes rather suitable for the purpose of this manuscript. Since it is transmitting significant amounts of data, this component will heat up considerably, so it should be placed in a space where it is ventilated during the flight. This video transmitter works combined with the antenna that will be described in the next subsection, due to the need to transfer the collected images to the module expected to send the data out of the UAV. As it will be explained later, both this video transmitter and the antenna it works with make use of the 802.11 ac wireless standard that transmits data at 5.8 GHz. 3. VTX Antenna AKK 5 dBi 5.8 GHz FPV [38]: this antenna is a component connected to the video transmitter. Its main function is the conversion of the electrical waves of the video signal into electromagnetic waves that the ground station will receive. In this case, an omnidirectional antenna with Right Hand Circular Polarization (RHCP) has been used, which implies that the receiver of the CGS must have an antenna polarized in the same way. An omnidirectional antenna will be used because it is the one that offers the greatest range for the transmission of video signals and therefore allows the operator to take the aircraft further from the ground station. For the usage of the 5.8 GHz band, the standard 802.11 ac has been used, which offers better security capabilities than other transmission systems due to including support for 256 bit AES keys and the Galois Counter Mode Protocol (GCMP) encryption protocol, which is more efficient and performs better when compared to Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP). In addition to that, a) the 5 GHz band is much less cluttered with traffic than the 2.4 GHz one, so data transmissions are more efficient and easier to deal with and b) Protocol Data Units (PDUs) have been further optimized (according to the Amendment 4 of the standard [39] \"_CCMP-128 processing expands the original MPDU size by 16 octets, 8 octets for the CCMP Header field and 8 octets for the MIC field. CCMP-256 processing expands the original MPDU size by 24 octets, 8 octets for the CCMP Header field, and 16 octets for the MIC field.\"_). 4. FPV goggles (Eachine EV800D) [40]: FPV goggles integrate several components that allow the operator to have visual information about what can be watched from the position of the UAV. Firstly, they incorporate a receiver for the video signal transmitted by it. This receiver transforms the received electromagnetic signal into an analog video signal.