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Communication Systems and Data Links Flashcards

7 cards from real UAS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Communication Systems and Data Links flashcards as text

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

    Answer: 2.4 GHz ISM band

    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.

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

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

    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.

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

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

    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.

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

    Answer: Free-space path loss

    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.

  5. What does RSSI measure in a UAS communication system?

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

    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.

  6. Why is Frequency Hopping Spread Spectrum (FHSS) used in some UAS control systems?

    Answer: To improve resistance to radio frequency interference and unauthorized signal interception

    FHSS rapidly switches the transmission across many frequencies in a pseudorandom sequence, making the control signal harder to jam, intercept, or disrupt by interference sources on a fixed frequency.

  7. What primarily limits the effective range of a standard UAS radio control link?

    Answer: Line-of-sight conditions and antenna gain characteristics

    Radio control link range is primarily limited by line-of-sight propagation conditions and antenna gain, since terrain, obstacles, and antenna directivity directly affect how well the signal travels between ground station and aircraft.