Drone and Defense Technology Glossary: Terms You Need to Know

As drone technology continues to transform mission-critical operations across defense, security, and industry, it's essential to understand the key terms shaping this evolving field. From autonomous navigation to BVLOS flight, the capabilities of both untethered and tethered drones are expanding rapidly. In particular, tethered drone systems—which provide continuous power and data through a secure cable connection—are becoming indispensable for long-endurance ISR, persistent surveillance, and communications relay. Whether you're integrating drones into your operations or seeking a deeper grasp of unmanned aerial systems, this guide breaks down essential terminology, including the distinct advantages of a tethered drone setup in high-stakes environments.

1. Autonomous Drone: A drone that operates without human intervention, guided by onboard systems and pre-programmed instructions. Autonomous drones are often integrated into both untethered and tethered drone systems to maximize efficiency. 

   
   

2. BVLOS (Beyond Visual Line of Sight): Drone operations conducted beyond the pilot's direct line of sight. Tethered drones only operate BVLOS when deployed independently of the pilot. Untethered drones require advanced communications, geolocation, and sense & avoid systems for BVLOS operations. 

   
   

3. C2 (Command and Control): Systems and protocols used to manage and control drones during missions, including flight commands and data transmission. Tethered drone systems often utilize high-speed wired connections for reliable C2 functions, which eliminates RF or other wireless signals. 

   
   

4. EO/IR (Electro-Optical/Infrared): Sensors that capture visual and thermal imagery, commonly mounted on tethered drones for continuous surveillance and on untethered drones for agile reconnaissance. 

   
   

5. Flight Endurance: The maximum time a drone can remain airborne without a battery change or fuel refill. Tethered drone systems offer unlimited flight endurance by drawing continuous power from the ground, while untethered drones are limited by battery life or fuel capacity. 

   
   

6. GPS Denied Navigation: Drone navigation in locations where GPS signals are unavailable or blocked. Tethered drones can operate in GPS-denied environments by maintaining a fixed position, while untethered drones may require advanced algorithms for positioning. 

   
   

7. ISR (Intelligence, Surveillance, Reconnaissance): Gathering data and monitoring activities through aerial platforms and various payloads (e.g., cameras, sensors, RADAR). Tethered drones are particularly valuable for ISR due to their ability to maintain a fixed, elevated position for long periods. 

   
   

8. Loiter Time: The duration a drone can remain airborne over a target area. Tethered drone systems excel in loiter time because they receive uninterrupted power from ground units, while untethered drones must return to base to recharge or refuel. 

   
   

9. Multi-Rotor Drone: A drone with multiple propellers (typically 4, 6, or 8), offering greater maneuverability and stability. Tethered multi-rotor drones are often used for ISR and communications, while untethered multi-rotors offer flexible, dynamic movement. 

   
   

10. Payload Capacity: The amount of weight a drone can carry, e.g., cameras, sensors, and other mission-critical equipment. Tethered drone systems have greater payload capacity than untethered drones since tethered drones do not need heavy batteries, have access to high power through the tether, and are often larger drones. The payload capacity of untethered drones varies based on their size, battery capacity, and design. 

    
    

11. Persistent Surveillance: Continuous ISR monitoring of a specific area or target. Tethered drones are ideal for persistent surveillance missions as they can remain airborne indefinitely, providing uninterrupted ISR, data collection, and live feeds. 

    
    

12. RPA (Remotely Piloted Aircraft): A drone piloted remotely by an operator. Both tethered and untethered drones usually can be controlled from a nearby ground station or a pilot remote from the flight area. 

    
    

13. RF (Radio Frequency) Communication: The transmission of data and control signals via radio waves, which can be interfered with or tracked by bad actors. Tethered drones can be flown and transmit their payload data without RF signals. Untethered drones must rely on vulnerable RF links for data transmission and control. 

    
    

14. Situational Awareness: The real-time understanding of an operational environment, often enhanced by aerial drone data and imagery. Tethered drones provide consistent situational awareness from a fixed vantage point, while untethered drones can quickly reposition as needed. 

    
    

15. Tethered Drone: A drone connected to a ground station via a cable, providing continuous power and data transmission. Tethered drones are commonly used for long-duration missions that require stable and consistent data flow, such as surveillance or communications relay. 

    
    

16. Tethered Drone System: A tethered drone and all related equipment needed for a mission. This often includes the tethered drone, the tether, a ground power unit, and a ground control station. If the collected data and signals need to be sent to a network or offsite location, backhaul equipment (e.g., satellite, microwave, MANET radio) will also be needed. These systems are designed for missions requiring extended loiter time and reliable data connectivity, making them perfect for military and defense applications. 

    
    

17. UAS (Unmanned Aerial System): A combination of an unmanned aircraft (drone) and its supporting components, including ground control systems and communication links.

    
    

18. UCAV (Unmanned Combat Aerial Vehicle): An armed drone designed for strike missions and offensive operations. While most UCAVs are untethered for mobility, there is growing interest in using tethered drones for overwatch, support and even kinetic uses during combat scenarios. 

    
    

19. VTOL (Vertical Takeoff and Landing): Drones capable of launching and landing vertically without the need for a runway. Many tethered drone systems feature VTOL capabilities to simplify deployment and

    
    
    
    

    recovery, especially in urban or rugged environments.