A Tethered Drone Power Supply (TDPS) is a revolutionary system that fundamentally solves the primary limitation of conventional drones—short flight endurance—by providing continuous power and data through a specialized cable, or tether, connecting the drone to a ground-based source. This system acts as an "umbilical cord," transforming the drone from a short-range tool into a persistent aerial platform capable of remaining aloft for dozens of hours, or even indefinitely, far surpassing the 20-45 minute limit of battery-powered flight. The core components of a TDPS include the ground power source, which can be a generator, mains electricity, or a vehicle's power system; the tether cable itself, a lightweight yet robust engineered marvel containing high-voltage power conductors for efficient energy transmission over long distances and fiber optics for secure, high-bandwidth data transfer; and an onboard power management module on the drone that converts and regulates the incoming power for the flight controllers, motors, and mission payloads. The paramount advantage of this technology is the creation of a persistent aerial presence, enabling 24/7 operations for applications such as permanent surveillance during critical infrastructure security, major event monitoring, and emergency response command and control. Furthermore, the secure fiber-optic link within the tether guarantees a stable, low-latency, and jam-resistant connection for real-time high-definition video and sensor data, which is crucial for situational awareness. This makes TDPS ideal for serving as a rapid-deployment communications relay to restore cellular or radio networks in disaster zones where ground infrastructure is compromised. While the system does trade the free-flight mobility of untethered drones for a limited operational radius defined by the tether's length and introduces greater deployment complexity and initial cost, its ability to provide unwavering power and reliable data link establishes it as an indispensable technology for missions where endurance, stability, and security are paramount.