Validating Drone Performance in Congested and Contested Electromagnetic Environments
Introduction
One of a drone's largest vulnerabilities is its radio signal, which forms a significant part of its mission. Critical information is transmitted and received that includes control, telemetry, pictures, and video.
A remote-control device forms the Ground Control Station (GCS), sending signals to the drone's aerial receiver, which then processes the commands to control the motors and other functions. The control link transmits information, such as altitude, speed, and remaining battery life, as well as feedback from the drone's mission, such as a live video feed from the drone's camera.

Drones can use different frequency bands to optimize performance. The ISM (Industrial Scientific Medical) band is widely used, especially for commercial drones, as it is unlicensed spectrum; however, other frequencies and stealth techniques are used, such as hopping and spread spectrum, to hide the signal from adversaries. A drone can also be autonomous, using only GPS or optical waypoints to complete its mission.
The principles of frequency, range, and bandwidth apply, with bandwidth decreasing as the distance from the GCS increases. However, there tends to be more transmitter congestion at lower frequencies.
For example, an ISM 2.4GHz signal can be used for longer-range control signals, but as discussed, this band is often crowded with other devices like Wi-Fi, Bluetooth, and even microwave ovens, which can cause interference. The 5GHz ISM band can be used for higher-speed video transmission due to its higher bandwidth and lower latency, providing a clearer video feed. This band has more channels and is less congested, but it does not travel as far as 2.4GHz signals and is more easily blocked by objects. Many advanced drones use a dual or multi-band system, dedicating 2.4GHz for control and 5GHz for video to get the best of both worlds.
Some drones can automatically switch between bands or allow the user to manually select the best one for their environment. For example, in a busy urban area, the drone might switch to 5GHz to avoid interference with other signals.