Practice Test Geeks(GROL) General Radiotelephone Operator License Practice Test
← All GROL Flashcard Decks

Modulation and Signal Types Flashcards

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

Read the first 7 Modulation and Signal Types flashcards as text

  1. In Frequency Shift Keying (FSK), how are binary 1s and 0s represented in the transmitted signal?

    Answer: By shifting between two distinct carrier frequencies

    FSK encodes binary data by switching the carrier between two preset frequencies: one representing a mark (logic 1) and one a space (logic 0).

  2. Which type of pulse modulation conveys information through variations in the duration (width) of each transmitted pulse?

    Answer: Pulse Width Modulation (PWM)

    Pulse Width Modulation (PWM), also called Pulse Duration Modulation (PDM), encodes the analog signal level as the time duration of each pulse.

  3. What ITU emission designator identifies frequency-shift keying used in radioteletype (RTTY) communications?

    Answer: F1B

    F1B designates frequency modulation (F) with a single digital channel and no modulating subcarrier (1) used for telegraphy (B), which describes direct FSK RTTY.

  4. In Quadrature Phase Shift Keying (QPSK), how many bits of data are encoded per transmitted symbol?

    Answer: 2 bits per symbol

    QPSK uses four phase states (0°, 90°, 180°, 270°), each uniquely identifying 2 bits, giving log₂(4) = 2 bits per symbol.

  5. What is the primary operational advantage of spread spectrum transmission techniques?

    Answer: Low probability of interception and high resistance to jamming and interference

    Spread spectrum disperses signal energy across a wide bandwidth, making it hard to detect, intercept, or jam and providing resistance to both intentional and unintentional interference.

  6. Which digital modulation scheme encodes information by simultaneously varying both the amplitude AND the phase of the carrier signal?

    Answer: Quadrature Amplitude Modulation (QAM)

    QAM combines amplitude and phase variations to create a constellation of discrete signal points, allowing multiple bits to be encoded per symbol.

  7. What emission designator identifies on-off keyed (OOK) continuous wave (CW) Morse code telegraphy?

    Answer: A1A

    A1A designates amplitude modulation (A) using a single digital channel without modulating subcarrier (1) for Morse code telegraphy (A), i.e., on-off CW keying.