Overview
In recent years, the drone industry has developed rapidly, and the application of drones has become increasingly widespread, with the number of drones also showing an increasing trend year by year. However, at the same time, drones also pose serious security threats to various places in society. In recent years, incidents of drones impacting and attacking critical infrastructure have occurred frequently, and there is an urgent need for effective drone countermeasures technology. There are several common drone countermeasures techniques, including:
- Wireless signal interference technology: By transmitting interference radio frequency signals, it interferes with wireless signals such as remote control, image transmission, navigation, etc. of unmanned aerial vehicles to achieve the purpose of driving away, interfering, or forcing landing of drone.
- Wireless signal deception technology: By transmitting deceptive wireless signals to drones, the drones can obtain incorrect information, thereby achievingthe purpose of hijacking drones. There are two main types of wireless signal deception techniques: location signal deception and remote control signal hijacking.
- Directed energy destruction technology: By emitting high-energy laser or electromagnetic signals, it physically destroys unmanned aerial vehicles, mainly through two technical routes: laser destruction and high-energy microwave destruction.
- Physical damage/capture technology: By launching bullets, cruise missiles, or colliding with drones, invading drones can be physically damaged, orshoot capture nets to capture invading drones.
This article mainly discusses wireless signal interference technology.
UAV Communication Protocol
Drones generally use the following four types of radio signals:
Figure 1 Typical wireless signal schematic of unmanned aerial vehicle
- RC：Remote Control：Transmitting instructions from the operator to the drone through remote control signals, allowing the drone to perform corresponding flight actions;
- Videotransmission：The video signal captured by the drone camera is transmitted back to the remote control, and the operator operates the drone based on the transmitted image signal to select the appropriate flight path and avoid hitting obstacles;
Navigation: Drones receive positioning signals from navigation satellites for their own positioning
The navigation signals seen include GPS, Beidou, GLONASS, etc., and the working frequency bands are mainly distributed around 1.2GHz and 1.6GHz.
- Telemetry：Used to distribute telemetry information such as the location of drones, which will be received by the remote control and nearby monitoring stations.
Among them, remote control signals and image feedback signals are the main targets of radio frequency interference countermeasures, and in some cases, they can also interfere with navigation and positioning signals. When interfering with remote control signals, the drone cannot receive instructions from the operator and will perform hovering or returning actions; When interfering with the image feedback signal, the remote control cannot display the image seen by the drone, which may cause the drone to lose control; When interfering with both remote control signals and navigation positioning signals, the drone cannot obtain accurate positioning information and lands directly, relying on ultrasonic sensors to avoid touching the ground and hovering at a certain height above the ground.
The following table lists some common drone remote control and image transmission protocols. Strong manufacturers such as DJI and AUTEL have developed dedicated remote control image transmission protocols, among which DJI's OcuSync and LightBridge are the most common and perform the best. For manufacturers who do not have self-developed remote control image transmission protocols, Wi Fi protocol is generally chosen. For DIY FPVs, the ELRS protocol and TBSCrossFire have become the actual standards.