UAS Communication Systems and Data Links

Question 1

What frequency band is most commonly used for UAS command and control (C2) links in consumer and commercial operations?

Accepted Answer

2.4 GHz ISM band

Answer

The 2.4 GHz ISM band is widely used for UAS C2 links because it is license-free, provides adequate range, and is supported by most RC and commercial UAS control systems.

Question 2

What does the term 'C2 link' refer to in UAS operations?

Accepted Answer

Command and Control link between the ground control station and the aircraft

Answer

The C2 (Command and Control) link is the bidirectional radio communication link that allows the remote pilot to send flight commands to the UAS and receive status information back.

Question 3

What is the primary function of a telemetry downlink in a UAS system?

Accepted Answer

Transmitting real-time aircraft status data such as altitude, speed, and battery level to the operator

Answer

The telemetry downlink sends real-time aircraft health and position data — including altitude, airspeed, GPS coordinates, and battery voltage — to the ground control station for operator awareness.

Question 4

Which phenomenon describes the reduction in radio signal strength as the distance between transmitter and receiver increases?

Accepted Answer

Free-space path loss

Answer

Free-space path loss describes how radio signal power decreases with the square of distance, which is the primary factor limiting the range of UAS control links in open environments.

Question 5

What does RSSI measure in a UAS communication system?

Accepted Answer

Received Signal Strength Indicator — the power level of the received radio signal

Answer

RSSI (Received Signal Strength Indicator) is a measurement of the power level of the radio signal being received, allowing operators to assess link quality and determine how close they are to the edge of reliable range.

(UAS) Unmanned Aircraft Systems Certified Practice Test

(UAS) Unmanned Aircraft Systems Certified Practice Test

UAS Communication Systems and Data Links