The combination, separation, and management of these wavelengths are achieved using various optical filters and multiplexing technologies, including interference-based coatings, integrated planar waveguide devices, in-fiber gratings, and tunable switching elements. Unlike the old traditional methods, the advantages of wavelet transform in singular signal detection and signal filtering are used to analyze the Optical Time Domain Reflec-tometer curve signal and the fault detection method of fiber communication links with no relay and a large span in a high. Unlike the old traditional methods, the advantages of wavelet transform in singular signal detection and signal filtering are used to analyze the Optical Time Domain Reflectometer curve signal and the fault detection method of fiber communication links with no relay and a large span in a high. The advantages of wavelet transform in singular signal detection and signal filtering are used to analyze Optical Time Domain Reflectometer (OTDR) curve signal and the fault detection method of fiber communication link with no relay and large span in high altitude area is given, which realizes the. Wavelength Frequency Filtering (WFF) emerges as a critical solution, enabling the integration of fiber optic systems without compromising the shielding integrity of enclosures. Patton's FiberPlex WGF series exemplifies this technology, offering innovative waveguide filters that facilitate the. High-altitude UAVs often fly at altitudes above 60,000 feet (≈ 18,300 meters), encountering pressures below 5 kPa and temperatures ranging from -60 °C to +85 °C. In this harsh stratospheric environment, every cable assembly must maintain power, control, and data integrity. Fiber-optics is an ideal medium for transporting various signals fr m inside a containment area to the outside world. Optical fibers are particularly well suited because the fiber, as well as the typical protective jackets, are non conductive and h.