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General exam G8: Signals and Emissions

All 42 questions in subelement G8. The exam asks 3 of them, one from each group (G8A, G8B, G8C). Answers are hidden until you open them.

Drill these 42 questions Full practice exam

G8A

  1. G8A01 How is direct binary FSK modulation generated?

    1. By keying an FM transmitter with a sub-audible tone
    2. By changing an oscillator’s frequency directly with a digital control signal
    3. By using a transceiver’s computer data interface protocol to change frequencies
    4. By reconfiguring the CW keying input to act as a tone generator
    Show answer

    B. By changing an oscillator’s frequency directly with a digital control signal

  2. G8A02 What is the name of the process that changes the phase angle of an RF signal to convey information?

    1. Phase convolution
    2. Phase modulation
    3. Phase transformation
    4. Phase inversion
    Show answer

    B. Phase modulation

  3. G8A03 What is the name of the process that changes the instantaneous frequency of an RF wave to convey information?

    1. Frequency convolution
    2. Frequency transformation
    3. Frequency conversion
    4. Frequency modulation
    Show answer

    D. Frequency modulation

  4. G8A04 What emission is produced by a reactance modulator connected to a transmitter RF amplifier stage?

    1. Multiplex modulation
    2. Phase modulation
    3. Amplitude modulation
    4. Pulse modulation
    Show answer

    B. Phase modulation

  5. G8A05 What type of modulation varies the instantaneous power level of the RF signal?

    1. Power modulation
    2. Phase modulation
    3. Frequency modulation
    4. Amplitude modulation
    Show answer

    D. Amplitude modulation

  6. G8A06 Which of the following is characteristic of QPSK31?

    1. It is sideband sensitive
    2. Its encoding provides error correction
    3. Its bandwidth is approximately the same as BPSK31
    4. All these choices are correct
    Show answer

    D. All these choices are correct

  7. G8A07 Which of the following phone emissions uses the narrowest bandwidth?

    1. Single sideband
    2. Vestigial sideband
    3. Phase modulation
    4. Frequency modulation
    Show answer

    A. Single sideband

  8. G8A08 Which of the following is an effect of overmodulation?

    1. Insufficient audio
    2. Insufficient bandwidth
    3. Frequency drift
    4. Excessive bandwidth
    Show answer

    D. Excessive bandwidth

  9. G8A09 What type of modulation is used by FT8?

    1. 8-tone frequency shift keying
    2. Vestigial sideband
    3. Amplitude compressed AM
    4. 8-bit direct sequence spread spectrum
    Show answer

    A. 8-tone frequency shift keying

  10. G8A10 What is meant by the term “flat-topping,” when referring to an amplitude-modulated phone signal?

    1. Signal distortion caused by insufficient collector current
    2. The transmitter’s automatic level control (ALC) is properly adjusted
    3. Signal distortion caused by excessive drive or speech levels
    4. The transmitter’s carrier is properly suppressed
    Show answer

    C. Signal distortion caused by excessive drive or speech levels

  11. G8A11 What is the modulation envelope of an AM signal?

    1. The waveform created by connecting the peak values of the modulated signal
    2. The carrier frequency that contains the signal
    3. Spurious signals that envelop nearby frequencies
    4. The bandwidth of the modulated signal
    Show answer

    A. The waveform created by connecting the peak values of the modulated signal

  12. G8A12 What is QPSK modulation?

    1. Modulation using quasi-parallel to serial conversion to reduce bandwidth
    2. Modulation using quadra-pole sideband keying to generate spread spectrum signals
    3. Modulation using Fast Fourier Transforms to generate frequencies at the first, second, third, and fourth harmonics of the carrier frequency to improve noise immunity
    4. Modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits
    Show answer

    D. Modulation in which digital data is transmitted using 0-, 90-, 180- and 270-degrees phase shift to represent pairs of bits

  13. G8A13 What is a link budget?

    1. The financial costs associated with operating a radio link
    2. The sum of antenna gains minus system losses
    3. The sum of transmit power and antenna gains minus system losses as seen at the receiver
    4. The difference between transmit power and receiver sensitivity
    Show answer

    C. The sum of transmit power and antenna gains minus system losses as seen at the receiver

  14. G8A14 What is link margin?

    1. The opposite of fade margin
    2. The difference between received power level and minimum required signal level at the input to the receiver
    3. Transmit power minus receiver sensitivity
    4. Receiver sensitivity plus 3 dB
    Show answer

    B. The difference between received power level and minimum required signal level at the input to the receiver

G8B

  1. G8B01 Which mixer input is varied or tuned to convert signals of different frequencies to an intermediate frequency (IF)?

    1. Image frequency
    2. Local oscillator
    3. RF input
    4. Beat frequency oscillator
    Show answer

    B. Local oscillator

  2. G8B02 What is the term for interference from a signal at twice the IF frequency from the desired signal?

    1. Quadrature response
    2. Image response
    3. Mixer interference
    4. Intermediate interference
    Show answer

    B. Image response

  3. G8B03 What is another term for the mixing of two RF signals?

    1. Heterodyning
    2. Synthesizing
    3. Frequency inversion
    4. Phase inversion
    Show answer

    A. Heterodyning

  4. G8B04 What is the stage in a VHF FM transmitter that generates a harmonic of a lower frequency signal to reach the desired operating frequency?

    1. Mixer
    2. Reactance modulator
    3. Balanced converter
    4. Multiplier
    Show answer

    D. Multiplier

  5. G8B05 Which intermodulation products are closest to the original signal frequencies?

    1. Second harmonics
    2. Even-order
    3. Odd-order
    4. Intercept point
    Show answer

    C. Odd-order

  6. G8B06 What is the total bandwidth of an FM phone transmission having 5 kHz deviation and 3 kHz modulating frequency?

    1. 3 kHz
    2. 5 kHz
    3. 8 kHz
    4. 16 kHz
    Show answer

    D. 16 kHz

  7. G8B07 What is the frequency deviation for a 12.21 MHz reactance modulated oscillator in a 5 kHz deviation, 146.52 MHz FM phone transmitter?

    1. 101.75 Hz
    2. 416.7 Hz
    3. 5 kHz
    4. 60 kHz
    Show answer

    B. 416.7 Hz

  8. G8B08 Why is it important to know the duty cycle of the mode you are using when transmitting?

    1. To aid in tuning your transmitter
    2. Some modes have high duty cycles that could exceed the transmitter’s average power rating
    3. To allow time for the other station to break in during a transmission
    4. To prevent overmodulation
    Show answer

    B. Some modes have high duty cycles that could exceed the transmitter’s average power rating

  9. G8B09 Why is it good to match receiver bandwidth to the bandwidth of the operating mode?

    1. It is required by FCC rules
    2. It minimizes power consumption in the receiver
    3. It improves impedance matching of the antenna
    4. It results in the best signal-to-noise ratio
    Show answer

    D. It results in the best signal-to-noise ratio

  10. G8B10 What is the relationship between transmitted symbol rate and bandwidth?

    1. Symbol rate and bandwidth are not related
    2. Higher symbol rates require wider bandwidth
    3. Lower symbol rates require wider bandwidth
    4. Bandwidth is half the symbol rate
    Show answer

    B. Higher symbol rates require wider bandwidth

  11. G8B11 What combination of a mixer’s Local Oscillator (LO) and RF input frequencies is found in the output?

    1. The ratio
    2. The average
    3. The sum and difference
    4. The arithmetic product
    Show answer

    C. The sum and difference

  12. G8B12 What process combines two signals in a non-linear circuit to produce unwanted spurious outputs?

    1. Intermodulation
    2. Heterodyning
    3. Detection
    4. Rolloff
    Show answer

    A. Intermodulation

  13. G8B13 Which of the following is an odd-order intermodulation product of frequencies F1 and F2?

    1. 5F1-3F2
    2. 3F1-F2
    3. 2F1-F2
    4. All these choices are correct
    Show answer

    C. 2F1-F2

G8C

  1. G8C02 Which digital mode is used as a low-power beacon for assessing HF propagation?

    1. WSPR
    2. MFSK16
    3. PSK31
    4. SSB-SC
    Show answer

    A. WSPR

  2. G8C03 What part of a packet radio frame contains the routing and handling information?

    1. Directory
    2. Preamble
    3. Header
    4. Trailer
    Show answer

    C. Header

  3. G8C04 Which of the following describes Baudot code?

    1. A 7-bit code with start, stop, and parity bits
    2. A code using error detection and correction
    3. A 5-bit code with additional start and stop bits
    4. A code using SELCAL and LISTEN
    Show answer

    C. A 5-bit code with additional start and stop bits

  4. G8C05 In an ARQ mode, what is meant by a NAK response to a transmitted packet?

    1. Request retransmission of the packet
    2. Packet was received without error
    3. Receiving station connected and ready for transmissions
    4. Entire file received correctly
    Show answer

    A. Request retransmission of the packet

  5. G8C06 What action results from a failure to exchange information due to excessive transmission attempts when using an ARQ mode?

    1. The checksum overflows
    2. The connection is dropped
    3. Packets will be routed incorrectly
    4. Encoding reverts to the default character set
    Show answer

    B. The connection is dropped

  6. G8C07 Which of the following narrow-band digital modes can receive signals with very low signal-to-noise ratios?

    1. MSK144
    2. FT8
    3. AMTOR
    4. MFSK32
    Show answer

    B. FT8

  7. G8C08 Which of the following statements is true about PSK31?

    1. Upper case letters are sent with more power
    2. Upper case letters use longer Varicode bit sequences and thus slow down transmission
    3. Error correction is used to ensure accurate message reception
    4. Higher power is needed as compared to RTTY for similar error rates
    Show answer

    B. Upper case letters use longer Varicode bit sequences and thus slow down transmission

  8. G8C09 Which is true of mesh network microwave nodes?

    1. Having more nodes increases signal strengths
    2. If one node fails, a packet may still reach its target station via an alternate node
    3. Links between two nodes in a network may have different frequencies and bandwidths
    4. More nodes reduce overall microwave out of band interference
    Show answer

    B. If one node fails, a packet may still reach its target station via an alternate node

  9. G8C10 How does forward error correction (FEC) allow the receiver to correct data errors?

    1. By controlling transmitter output power for optimum signal strength
    2. By using the Varicode character set
    3. By transmitting redundant information with the data
    4. By using a parity bit with each character
    Show answer

    C. By transmitting redundant information with the data

  10. G8C11 How are the two separate frequencies of a Frequency Shift Keyed (FSK) signal identified?

    1. Dot and dash
    2. On and off
    3. High and low
    4. Mark and space
    Show answer

    D. Mark and space

  11. G8C12 Which type of code is used for sending characters in a PSK31 signal?

    1. Varicode
    2. Viterbi
    3. Volumetric
    4. Binary
    Show answer

    A. Varicode

  12. G8C13 What is indicated on a waterfall display by one or more vertical lines on either side of a data mode or RTTY signal?

    1. Long path propagation
    2. Backscatter propagation
    3. Insufficient modulation
    4. Overmodulation
    Show answer

    D. Overmodulation

  13. G8C14 Which of the following describes a waterfall display?

    1. Frequency is horizontal, signal strength is vertical, time is intensity
    2. Frequency is vertical, signal strength is intensity, time is horizontal
    3. Frequency is horizontal, signal strength is intensity, time is vertical
    4. Frequency is vertical, signal strength is horizontal, time is intensity
    Show answer

    C. Frequency is horizontal, signal strength is intensity, time is vertical

  14. G8C15 What does an FT8 signal report of +3 mean?

    1. The signal is 3 times the noise level of an equivalent SSB signal
    2. The signal is S3 (weak signals)
    3. The signal-to-noise ratio is equivalent to +3dB in a 2.5 kHz bandwidth
    4. The signal is 3 dB over S9
    Show answer

    C. The signal-to-noise ratio is equivalent to +3dB in a 2.5 kHz bandwidth

  15. G8C16 Which of the following provide digital voice modes?

    1. WSPR, MFSK16, and EasyPAL
    2. FT8, FT4, and FST4
    3. Winlink, PACTOR II, and PACTOR III
    4. DMR, D-STAR, and SystemFusion
    Show answer

    D. DMR, D-STAR, and SystemFusion

Questions: NCVEC Question Pool Committee (public domain). Pool valid July 1, 2023 – June 30, 2027.