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Amateur Radio 2024 - General > G8 – SIGNALS AND EMISSIONS [3 Exam Questions – 3 Groups] 43 Questions > Flashcards

G8 – SIGNALS AND EMISSIONS [3 Exam Questions – 3 Groups] 43 Questions Flashcards

1
Q

“How is direct binary FSK modulation generated?”

A. By keying an FM transmitter with a sub-audible tone
B. By changing an oscillator’s frequency directly with a digital control signal
C. By using a transceiver’s computer data interface protocol to change frequencies
D. By reconfiguring the CW keying input to act as a tone generator

A

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

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2
Q

“What is the name of the process that changes the phase angle of an RF signal to convey information?”

A. Phase convolution
B. Phase modulation
C. Phase transformation
D. Phase inversion

A

B. Phase modulation

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3
Q

“What is the name of the process that changes the instantaneous frequency of an RF wave to convey information?”

A. Frequency convolution
B. Frequency transformation
C. Frequency conversion
D. Frequency modulation

A

D. Frequency modulation

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4
Q

“What emission is produced by a reactance modulator connected to a transmitter RF amplifier stage?”

A. Multiplex modulation
B. Phase modulation
C. Amplitude modulation
D. Pulse modulation

A

B. Phase modulation

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5
Q

“What type of modulation varies the instantaneous power level of the RF signal?”

A. Power modulation
B. Phase modulation
C. Frequency modulation
D. Amplitude modulation

A

D. Amplitude modulation

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6
Q

“Which of the following is characteristic of QPSK31?”

A. It is sideband sensitive
B. Its encoding provides error correction
C. Its bandwidth is approximately the same as BPSK31
D. All these choices are correct

A

D. All these choices are correct

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7
Q

“Which of the following phone emissions uses the narrowest bandwidth?”

A. Single sideband
B. Vestigial sideband
C. Phase modulation
D. Frequency modulation

A

A. Single sideband

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8
Q

“Which of the following is an effect of overmodulation?”

A. Insufficient audio
B. Insufficient bandwidth
C. Frequency drift
D. Excessive bandwidth

A

D. Excessive bandwidth

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9
Q

“What type of modulation is used by FT8?”

A. 8-tone frequency shift keying
B. Vestigial sideband
C. Amplitude compressed AM
D. 8-bit direct sequence spread spectrum

A

A. 8-tone frequency shift keying

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10
Q

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

A. Signal distortion caused by insufficient collector current
B. The transmitter’s automatic level control (ALC) is properly adjusted
C. Signal distortion caused by excessive drive or speech levels
D. The transmitter’s carrier is properly suppressed

A

C. Signal distortion caused by excessive drive or speech levels

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11
Q

“What is the modulation envelope of an AM signal?”

A. The waveform created by connecting the peak values of the modulated signal
B. The carrier frequency that contains the signal
C. Spurious signals that envelop nearby frequencies
D. The bandwidth of the modulated signal

A

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

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12
Q

“What is QPSK modulation?”

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

A

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

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13
Q

“What is a link budget?”

A. The financial costs associated with operating a radio link
B. The sum of antenna gains minus system losses
C. The sum of transmit power and antenna gains minus system losses as seen at the receiver
D. The difference between transmit power and receiver sensitivity

A

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

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14
Q

“What is link margin?”

A. The opposite of fade margin
B. The difference between received power level and minimum required signal level at the input to the receiver
C. Transmit power minus receiver sensitivity
D. Receiver sensitivity plus 3 dB

A

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

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15
Q

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

A. Image frequency
B. Local oscillator
C. RF input
D. Beat frequency oscillator

A

B. Local oscillator

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16
Q

“What is the term for interference from a signal at twice the IF frequency from the desired signal?”

A. Quadrature response
B. Image response
C. Mixer interference
D. Intermediate interference

A

B. Image response

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17
Q

“What is another term for the mixing of two RF signals?”

A. Heterodyning
B. Synthesizing
C. Frequency inversion
D. Phase inversion

A

A. Heterodyning

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18
Q

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

A. Mixer
B. Reactance modulator
C. Balanced converter
D. Multiplier

A

D. Multiplier

19
Q

“Which intermodulation products are closest to the original signal frequencies?”

A. Second harmonics
B. Even-order
C. Odd-order
D. Intercept point

A

C. Odd-order

20
Q

“What is the total bandwidth of an FM phone transmission having 5 kHz deviation and 3 kHz modulating frequency?”

A. 3 kHz
B. 5 kHz
C. 8 kHz
D. 16 kHz

A

D. 16 kHz

21
Q

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

A. 101.75 Hz
B. 416.7 Hz
C. 5 kHz
D. 60 kHz

A

B. 416.7 Hz

22
Q

“Why is it important to know the duty cycle of the mode you are using when transmitting?”

A. To aid in tuning your transmitter
B. Some modes have high duty cycles that could exceed the transmitter’s average power rating
C. To allow time for the other station to break in during a transmission
D. To prevent overmodulation

A

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

23
Q

“Why is it good to match receiver bandwidth to the bandwidth of the operating mode?”

A. It is required by FCC rules
B. It minimizes power consumption in the receiver
C. It improves impedance matching of the antenna
D. It results in the best signal-to-noise ratio

A

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

24
Q

“What is the relationship between transmitted symbol rate and bandwidth?”

A. Symbol rate and bandwidth are not related
B. Higher symbol rates require wider bandwidth
C. Lower symbol rates require wider bandwidth
D. Bandwidth is half the symbol rate

A

B. Higher symbol rates require wider bandwidth

25
Q

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

A. The ratio
B. The average
C. The sum and difference
D. The arithmetic product

A

C. The sum and difference

26
Q

“What process combines two signals in a non-linear circuit to produce unwanted spurious outputs?”

A. Intermodulation
B. Heterodyning
C. Detection
D. Rolloff

A

A. Intermodulation

27
Q

“Which of the following is an odd-order intermodulation product of frequencies F1 and F2?”

A. 5F1-3F2
B. 3F1-F2
C. 2F1-F2
D. All these choices are correct

A

C. 2F1-F2

28
Q

“On what band do amateurs share channels with the unlicensed Wi-Fi service?”

A. 432 MHz
B. 902 MHz
C. 2.4 GHz
D. 10.7 GHz

A

C. 2.4 GHz

29
Q

“Which digital mode is used as a low-power beacon for assessing HF propagation?”

A. WSPR
B. MFSK16
C. PSK31
D. SSB-SC

A

A. WSPR

30
Q

“What part of a packet radio frame contains the routing and handling information?”

A. Directory
B. Preamble
C. Header
D. Trailer

A

C. Header

31
Q

“Which of the following describes Baudot code?”

A. A 7-bit code with start, stop, and parity bits
B. A code using error detection and correction
C. A 5-bit code with additional start and stop bits
D. A code using SELCAL and LISTEN

A

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

32
Q

“In an ARQ mode, what is meant by a NAK response to a transmitted packet?”

A. Request retransmission of the packet
B. Packet was received without error
C. Receiving station connected and ready for transmissions
D. Entire file received correctly

A

A. Request retransmission of the packet

33
Q

“What action results from a failure to exchange information due to excessive transmission attempts when using an ARQ mode?”

A. The checksum overflows
B. The connection is dropped
C. Packets will be routed incorrectly
D. Encoding reverts to the default character set

A

B. The connection is dropped

34
Q

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

A. MSK144
B. FT8
C. AMTOR
D. MFSK32

A

B. FT8

35
Q

“Which of the following statements is true about PSK31?”

A. Upper case letters are sent with more power
B. Upper case letters use longer Varicode bit sequences and thus slow down transmission
C. Error correction is used to ensure accurate message reception
D. Higher power is needed as compared to RTTY for similar error rates

A

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

36
Q

“Which is true of mesh network microwave nodes?”

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

A

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

37
Q

“How does forward error correction (FEC) allow the receiver to correct data errors?”

A. By controlling transmitter output power for optimum signal strength
B. By using the Varicode character set
C. By transmitting redundant information with the data
D. By using a parity bit with each character

A

C. By transmitting redundant information with the data

38
Q

“How are the two separate frequencies of a Frequency Shift Keyed (FSK) signal identified?”

A. Dot and dash
B. On and off
C. High and low
D. Mark and space

A

D. Mark and space

39
Q

“Which type of code is used for sending characters in a PSK31 signal?”

A. Varicode
B. Viterbi
C. Volumetric
D. Binary

A

A. Varicode

40
Q

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

A. Long path propagation
B. Backscatter propagation
C. Insufficient modulation
D. Overmodulation

A

D. Overmodulation

41
Q

“Which of the following describes a waterfall display?”

A. Frequency is horizontal, signal strength is vertical, time is intensity
B. Frequency is vertical, signal strength is intensity, time is horizontal
C. Frequency is horizontal, signal strength is intensity, time is vertical
D. Frequency is vertical, signal strength is horizontal, time is intensity

A

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

42
Q

“What does an FT8 signal report of +3 mean?”

A. The signal is 3 times the noise level of an equivalent SSB signal
B. The signal is S3 (weak signals)
C. The signal-to-noise ratio is equivalent to +3dB in a 2.5 kHz bandwidth
D. The signal is 3 dB over S9

A

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

43
Q

“Which of the following provide digital voice modes?”

A. WSPR, MFSK16, and EasyPAL
B. FT8, FT4, and FST4
C. Winlink, PACTOR II, and PACTOR III
D. DMR, D-STAR, and SystemFusion

A

D. DMR, D-STAR, and SystemFusion

Amateur Radio 2024 - General (10 decks)

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