https://www.911security.com/learn/airspace-security/drone-fundamentals/drone-communication-data-link

UAV Control (ground to uav)

• Fly: throttle, yaw, pitch, roll
• Settings
• Flight modes and manuevers
• Camera gimbal

Video (uav to ground)

Telemetry (uav to ground)

• Sensor readings: GPS, compass, altimeter, speed, orientation
• Battery charge level

RF radio frequency

• long range, up to 50 miles
• 900MHz to 5.8GHz, controlled by FCC

WiFi

• 100m range, can be extended with Xiaomi Mi Wifi Extender
• 802.11

2.4 GHz

BT Bluetooth

• 60m range
• useful to configure the FC from your phone via the SpeedyBee Android app
• 2.4 GHz

Inverse relationship between frequency and wavelength.

• High frequency ⇒ short wavelength
• Low frequency ⇒ long wavelength

Long wavelength radio waves have ability to get around trees and other obstacles.

Short wavelength signals have longer range.

The most popular data links used in a UAS are 2.4Ghz and 900Mhz.

• 4Ghz – 1 mile range, does not do well in mountainous or wooded areas.
• 900Mhz – 60+ mile range, can be used in mountainous and wooded areas with little to no effect on range.

The most popular data links used in a UAS are 1.3Ghz, 2.4Ghz, and 5.8Ghz

• 3Ghz – Depending on the wattage used, this system can have a range of 40+ miles. The downfall of this system is poor video quality due to minimum data rates. However, since the wavelength is relatively long enabling stronger penetration capabilities.
• 4Ghz – This system can have a range of 15+ miles. The downfall of this system is many of the UAVs use 2.4Ghz for control. If 2.4Ghz is used for video, it cannot be used for control or this will cause interference.
• 8Ghz – This is the most popular frequency used for video transmission due to its short wavelength and large data rate transfer capability. This results in a clear video compared to the other options available. However, due to the short wavelength this system is only capable of 5+ miles and has limited penetrating capability.