87 lines
3.9 KiB
Markdown
87 lines
3.9 KiB
Markdown
G8A – Carriers and modulation: AM, FM, and single sideband; modulation envelope; digital modulation; overmodulation; link budgets and link margins
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- [[G8A01]] (B)
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How is direct binary FSK modulation generated? #card
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- A. By keying an FM transmitter with a sub-audible tone
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- B. By changing an oscillator’s frequency directly with a digital control signal
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- C. By using a transceiver’s computer data interface protocol to change frequencies
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- D. By reconfiguring the CW keying input to act as a tone generator
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- [[G8A02]] (B)
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What is the name of the process that changes the phase angle of an RF signal to convey information? #card
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- A. Phase convolution
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- B. Phase modulation
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- C. Phase transformation
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- D. Phase inversion
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- [[G8A03]] (D)
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What is the name of the process that changes the instantaneous frequency of an RF wave to convey information? #card
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- A. Frequency convolution
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- B. Frequency transformation
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- C. Frequency conversion
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- D. Frequency modulation
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- [[G8A04]] (B)
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What emission is produced by a reactance modulator connected to a transmitter RF amplifier stage? #card
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- A. Multiplex modulation
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- B. Phase modulation
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- C. Amplitude modulation
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- D. Pulse modulation
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- [[G8A05]] (D)
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What type of modulation varies the instantaneous power level of the RF signal? #card
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- A. Power modulation
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- B. Phase modulation
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- C. Frequency modulation
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- D. Amplitude modulation
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- [[G8A06]] (D)
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Which of the following is characteristic of QPSK31? #card
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- A. It is sideband sensitive
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- B. Its encoding provides error correction
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- C. Its bandwidth is approximately the same as BPSK31
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- D. All these choices are correct
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- [[G8A07]] (A)
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Which of the following phone emissions uses the narrowest bandwidth? #card
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- A. Single sideband
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- B. Vestigial sideband
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- C. Phase modulation
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- D. Frequency modulation
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- [[G8A08]] (D)
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Which of the following is an effect of overmodulation? #card
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- A. Insufficient audio
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- B. Insufficient bandwidth
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- C. Frequency drift
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- D. Excessive bandwidth
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- [[G8A09]] (A)
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What type of modulation is used by FT8? #card
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- A. 8-tone frequency shift keying
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- B. Vestigial sideband
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- C. Amplitude compressed AM
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- D. 8-bit direct sequence spread spectrum
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- [[G8A10]] (C)
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What is meant by the term “flat-topping,” when referring to an amplitude-modulated phone signal? #card
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- A. Signal distortion caused by insufficient collector current
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- B. The transmitter’s automatic level control (ALC) is properly adjusted
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- C. Signal distortion caused by excessive drive or speech levels
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- D. The transmitter’s carrier is properly suppressed
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- [[G8A11]] (A)
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What is the modulation envelope of an AM signal? #card
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- A. The waveform created by connecting the peak values of the modulated signal
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- B. The carrier frequency that contains the signal
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- C. Spurious signals that envelop nearby frequencies
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- D. The bandwidth of the modulated signal
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- [[G8A12]] (D)
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What is QPSK modulation? #card
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- A. Modulation using quasi-parallel to serial conversion to reduce bandwidth
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- B. Modulation using quadra-pole sideband keying to generate spread spectrum signals
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- 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
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- 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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- [[G8A13]] (C)
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What is a link budget? #card
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- A. The financial costs associated with operating a radio link
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- B. The sum of antenna gains minus system losses
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- C. The sum of transmit power and antenna gains minus system losses as seen at the receiver
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- D. The difference between transmit power and receiver sensitivity
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- [[G8A14]] (B)
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What is link margin? #card
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- A. The opposite of fade margin
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- B. The difference between received power level and minimum required signal level at the input to the receiver
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- C. Transmit power minus receiver sensitivity
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- D. Receiver sensitivity plus 3 dB
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