# Flying Watchdog-Based Guard Patrol with Check Point Data Verification
## 4 Results and Discussion
### Validation and Testing in an Outdoor Environment  
The objective of the outdoor testing phase was to confirm the efficacy of the developed aerial watchdog system for PGP detection, utilizing a unique red dot square pattern. In  
Figure 14: Laser beam divergence according to distance. Figure 13: The effect of laser on a solar panel: (**a**) distance; (**b**) average output voltage. Figure 10, we can observe the system's ability to identify a red LED even at a height of up to 6 m, even when operating in low-light conditions. The method leverages the power of the NVIDIA Jetson platform, offering drone control over three rotational axes: pitch, roll, and yaw angles. Figure 15 provides an overview of the outdoor testing environment, while Figure 7 illustrates sample outcomes during the search mode. Our research reveals that when the target falls within the camera's field of view, the sensing camera exhibits remarkable responsiveness, swiftly detecting and interpreting the LED as a square dot in just 1 millisecond. The findings are illustrated through a binary edge map within the mask frame, where white pixels signify detected edges. The fusion of previously discussed methods, including Gaussian smoothing, gradient computation, non-maximum suppression, and hysteresis thresholding, enhances the robustness of this image detection and classification technique. This rapid detection capability facilitates seamless laser data transmission, allowing for an uninterrupted 8-s window for data transmission. The Arduino-based laser communication system transmits data in 8-bit chunks to the PGP. Initially, it takes each incoming data byte received from the serial interface and splits it into two 4-bit nibbles. These nibbles are encoded into 8-bit integers using Hamming encoding, significantly enhancing the system's error detection and correction capabilities. Following this encoding step, the system introduces modulation by adding start and stop bits to ensure synchronization. During the modulation process, each bit is transformed into two half-bits, each accompanied by a clock pulse. Logical '1's are represented as 'on' states, while '0's are depicted as 'off' states, ensuring a robust and reliable data representation. The reconstructed byte is transmitted seamlessly through the serial interface, completing the communication cycle. Figure 16 illustrates the transmission process of continuous 8-bit data, specifically '101011' and '1101001,' with the start and stop bits represented by a logic '0'. This dedicated transmission method is capable of sending 8 bits of data at a rate of 117 Hz or within 8.5 milliseconds. This transmission speed is well-suited for seamless data reception and interpretation by the microcontroller, thereby ensuring error-free communication. The results of this process can be conveniently monitored through a serial monitor tool. In this study, using LEDs as a marker poses challenges regarding light dispersion, influenced by various factors such as LED size, color, and type. Similarly, regarding vision detectors, the viewing angle and diffusers can significantly impact the reading process. Implementing a kernel function filtering mechanism and an edge detection method to address the issue of light dispersion, particularly in the context of wide-angle LEDs, has proven successful. These findings underscore that even a 5 mm LED with a 0.06 A current and a 5 V power supply can be detected by a vision sensor at distances of up to 20 m, mainly when the LED emits white light. However, in our investigation of the detection of traffic lights, the LEDs utilized are more extensive and equipped with LED reflectors, resulting in  
Figure 15: Flying watchdog outdoor test. (**a**) Flying watchdog; (**b**) PGP; (**c**) detector; (**d**) masking. brighter light emissions. In data transmission via laser technology, we departed from using laser optical communication equipment and opted for a more straightforward system.