## 4 Results and Discussion  
This section presents the experimental results obtained with the proposed photonic and wireless monitoring system for knee-referenced gait cycles. The results include both raw and processed data, demonstrating the system's capability to accurately measure knee kinematics in different test conditions. Additionally, the results highlight the system's consistency, versatility, and potential for clinical and sports-related applications, supporting the system's effectiveness for monitoring and analyzing human gait dynamics. The experimental results obtained with the proposed photonic and wireless monitoring system for knee-referenced gait cycles demonstrate the system's capability to deliver high-resolution, accurate, and reliable measurements of knee kinematics. The data collected through both the Fiber Bragg Grating (FBG) sensor and the wireless inertial modules align well with the study's objectives, confirming the system's potential for clinical and sports-related applications. This study's primary highlights include high sensitivity and accuracy, system versatility, and applicability in biomedical and sports contexts. The analysis of the results supports these aspects: (i) High Sensitivity and Accuracy: The FBG sensor, with its 10 p.m. resolution, effectively captured the subtle flexion and extension movements of the knee. The obtained waveforms accurately reflected the stance and swing phases of the gait cycle, validating the system's capability to provide precise kinematic data without the need for complex motion capture systems. (ii) System Versatility: The system was tested on seven volunteers with varied physical attributes, demonstrating consistent performance across different scenarios. The adaptable knee band design, combined with the flexible sensor setup, allowed the system to accommodate different body sizes and ensure accurate measurements in both clinical and athletic settings. (iii) Biomedical and Sports Applications: The monitoring system proved effective in environments that required detailed analysis of limb movements. Its high resolution and reliable data acquisition support its use in physical therapy to monitor rehabilitation progress and in sports training to evaluate performance and tailor exercise programs. To provide a comprehensive understanding of the system's performance and its alignment with the research objectives, the following sections delve into detailed observations from the experimental data, address system limitations, and evaluate how the results support both this study's objectives and potential future advancements. Preliminary measurements using the unmodified FBG prototype showed smooth waveforms at low speeds. However, when speeds exceeded 4 km/h, the elasticity of the knee band and movement-induced slip caused minor shifts in the FBG's position. This shift, even slight, impacted the high-resolution data output, highlighting the need for precise sensor positioning, particularly for leg circumferences differing from the ideal 35-38 cm range. Such variances led to wavelength fluctuations due to leg vibrations during movement, as evidenced by the sharper waveform peaks at 8 km/h. To mitigate these effects, solutions include using knee bands of varying sizes or embedding the sensor within the textile of the elastic knee band. Regarding the wireless sensor modules, fast changes in the data were attributed to the attachment mechanism, which occasionally allowed slight vibrations. A more secure interface between the sensors and the leg could improve measurement stability. While the FBG sensor's placement needs refinement to avoid inaccuracies at higher speeds, the inertial sensors consistently measured the relative angle between the modules, demonstrating robustness regardless of their exact placement on the leg.