3.8 KiB
3.8 KiB
G8A – Carriers and modulation: AM, FM, and single sideband; modulation envelope; digital modulation; overmodulation; link budgets and link margins
- G8A01 (B)
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
- G8A02 (B)
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
- G8A03 (D)
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
- G8A04 (B)
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
- G8A05 (D)
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
- G8A06 (D)
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
- G8A07 (A)
Which of the following phone emissions uses the narrowest bandwidth?
- A. Single sideband
- B. Vestigial sideband
- C. Phase modulation
- D. Frequency modulation
- G8A08 (D)
Which of the following is an effect of overmodulation?
- A. Insufficient audio
- B. Insufficient bandwidth
- C. Frequency drift
- D. Excessive bandwidth
- G8A09 (A)
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
- G8A10 (C)
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
- G8A11 (A)
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
- G8A12 (D)
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
- G8A13 (C)
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
- G8A14 (B)
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