## 4 Results and Analysis of the Flight Test
### Test Objects and Technical Indicators  
The flight test also verifies whether the performance of ground observation systems and wireless communication systems meets the needs of real-time monitoring of natural disasters. In flight tests, the ground observation system suitable for natural disaster monitoring is a combination of orthographic stabilization platform and visible light cameras loaded on it, while the wireless communication system is composed of airborne communication equipment. The orthographic stabilization platform and airborne communication equipment are non-standard-design equipment, and their performance during the flight test to a certain extent reflects their ability to complete tasks. Therefore, this test mainly analyzes the performance of the orthographic stabilization platform and its optical load as well as the transmission capacity of the airborne communication equipment in the flight environment.  
The flight system includes aircraft, communication equipment, and orthographic stabilization platform (Figure 5b). The technical indicators of the communication equipment and the orthographic stabilization platform in flight tests are the same as those of the ground test mentioned above. Due to the differences between the aircraft used in flight tests and the typical aircraft expected during ground testing, the key indicators of the stabilization platform vary due to changes in flight altitude, speed, and other parameters. Considering the index condition of Camel 500 (flight altitude of 200-500 m, speed less than 100 km/h, fuselage roll of \(\pm\)10\({}^{\circ}\), and cycle of 7 s) in flight tests, in order to meet the task of detecting ground targets and effectively splicing the photos taken by the camera, the optical axis must be limited to a certain range of fluctuations to ensure that the overlapping area of adjacent two frames of images is not less than 1/4. Considering the aircraft's speed and photography frequency of 1 s, the aircraft's travel per second is \(\sim\)28 m. If the overlap area  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Transmission Bandwidths** & **Number of Sent Packets** & \multicolumn{2}{c}{**Eb/No**} & \multicolumn{2}{c}{**Number of Received Packets**} & \multicolumn{2}{c}{**Number of Lost Packets**} & \multicolumn{2}{c}{**Packet Lost Rate (\%)**} \\ \cline{3-10}  & **Satellite** & **Dynamic** & **Static** & **Dynamic** & **Static** & **Dynamic** & **Static** & **Dynamic** \\ \hline
256 Kbps & 1000 & 11.0 & 11.1 & 999 & 997 & 1 & 3 & 0.1 & 0.3 \\
512 Kbps & 1000 & 10.1 & 9.8 & 1000 & 998 & 0 & 2 & 0 & 0.2 \\
1024 Kbps & 1000 & 7.2 & 7.1 & 1000 & 996 & 0 & 4 & 0 & 0.4 \\
2048 Kbps & 1000 & 4.3 & 4.2 & 998 & 995 & 2 & 10 & 0.2 & 0.5 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Static and dynamic test data of the airborne communication system.  
of the two frames of images is not less than 1/4, the coverage distance of each frame of images in the flight direction is ~37 m. When the target distance is 500 m, the corresponding FOV angle is calculated by Formula (1) to be 4.23\({}^{\circ}\). According to Formula (2), if the stable accuracy is less than 1.05\({}^{\circ}\), the effectiveness of image stitching can be ensured.