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SUBELEMENT G8 -- SIGNALS AND EMISSIONS
[2 Exam Questions -- 2 Groups]

G8A Signal information; AM; FM; single and double sideband and carrier; bandwidth; modulation envelope; deviation; overmodulation

G8A01
What type of modulation system changes the amplitude of an RF wave for the purpose of conveying information?
A. Frequency modulation
B. Phase modulation
C. Amplitude-rectification modulation
D. Amplitude modulation

G8A02 (B)
What type of modulation system changes the phase of an RF 
wave for the purpose of conveying information?
A.   Pulse modulation
B.   Phase modulation
C.   Phase-rectification modulation
D.   Amplitude modulation

G8A03 (D)
What type of modulation system changes the frequency of an 
RF wave for the purpose of conveying information?
A.   Phase-rectification modulation
B.   Frequency-rectification modulation
C.   Amplitude modulation
D.   Frequency modulation

G8A04 (B)
What emission is produced by a reactance modulator 
connected to an RF power amplifier?
A.   Multiplex modulation
B.   Phase modulation
C.   Amplitude modulation
D.   Pulse modulation

G8A05 (D)
In what emission type does the instantaneous amplitude 
(envelope) of the RF signal vary in accordance with the 
modulating audio?
A.   Frequency shift keying
B.   Pulse modulation
C.   Frequency modulation
D.   Amplitude modulation

[G8A06 - This question has been formally withdrawn by the QPC. It will not be used on tests.]
G8A06 (C)
How much should the carrier be suppressed below peak output 
power in a properly designed single-sideband (SSB) 
transmitter?
A.   No more than 20 dB
B.   No more than 30 dB
C.   At least 40 dB
D.   At least 60 dB

G8A07 (C)
What is one advantage of carrier suppression in a double-
sideband phone transmission?
A.   Only half the bandwidth is required for the same 
information content
B.   Greater modulation percentage is obtainable with lower 
distortion
C.   More power can be put into the sidebands
D.   Simpler equipment can be used to receive a double-
sideband suppressed-carrier signal

G8A08 (A)
Which popular phone emission uses the narrowest frequency 
bandwidth?
A.   Single-sideband
B.   Double-sideband
C.   Phase-modulated
D.   Frequency-modulated

G8A09 (D)
What happens to the signal of an overmodulated single-
sideband or double-sideband phone transmitter?
A.   It becomes louder with no other effects
B.   It occupies less bandwidth with poor high-frequency 
response
C.   It has higher fidelity and improved signal-to-noise 
ratio
D.   It becomes distorted and occupies more bandwidth

G8A10 (B)
How should the microphone gain control be adjusted on a 
single-sideband phone transmitter?
A.   For full deflection of the ALC meter on modulation 
peaks
B.   For slight movement of the ALC meter on modulation 
peaks
C.   For 100% frequency deviation on modulation peaks
D.   For a dip in plate current

G8A11 (C)
What is meant by flattopping in a single-sideband phone 
transmission?
A.   Signal distortion caused by insufficient collector 
current
B.   The transmitter's automatic level control is properly 
adjusted
C.   Signal distortion caused by excessive drive
D.   The transmitter's carrier is properly suppressed

G8A12 (A)
What happens to the RF carrier signal when a modulating 
audio signal is applied to an FM transmitter?
A.   The carrier frequency changes proportionally to the 
instantaneous amplitude of the modulating signal
B.   The carrier frequency changes proportionally to the 
amplitude and frequency of the modulating signal
C.   The carrier amplitude changes proportionally to the 
instantaneous frequency of the modulating signal
D.   The carrier phase changes proportionally to the 
instantaneous amplitude of the modulating signal

G8A13 (A)
What signal(s) would be found at the output of a properly 
adjusted balanced modulator?
A.   Both upper and lower sidebands
B.   Either upper or lower sideband, but not both
C.   Both upper and lower sidebands and the carrier
D.   The modulating signal and the unmodulated carrier

G8B Frequency mixing; multiplication; bandwidths; HF data communications
G8B01 (A) What receiver stage combines a 14.25-MHz input signal with a 13.795-MHz oscillator signal to produce a 455-kHz intermediate frequency (IF) signal? A. Mixer B. BFO C. VFO D. Multiplier G8B02 (B) If a receiver mixes a 13.800-MHz VFO with a 14.255-MHz received signal to produce a 455-kHz intermediate frequency (IF) signal, what type of interference will a 13.345-MHz signal produce in the receiver? A. Local oscillator B. Image response C. Mixer interference D. Intermediate interference G8B03 (A) What stage in a transmitter would change a 5.3-MHz input signal to 14.3 MHz? A. A mixer B. A beat frequency oscillator C. A frequency multiplier D. A linear translator G8B04 (D) What is the name of the stage in a VHF FM transmitter that selects a harmonic of an HF signal to reach the desired operating frequency? A. Mixer B. Reactance modulator C. Preemphasis network D. Multiplier G8B05 (C) Why isn't frequency modulated (FM) phone used below 29.5 MHz? A. The transmitter efficiency for this mode is low B. Harmonics could not be attenuated to practical levels C. The bandwidth would exceed FCC limits D. The frequency stability would not be adequate G8B06 (D) What is the total bandwidth of an FM-phone transmission having a 5-kHz deviation and a 3-kHz modulating frequency? A. 3 kHz B. link=5 kHz C. 8 kHz D. 16 kHz G8B07 (B) 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. 41.67 Hz B. 416.7 Hz C. 5 kHz D. 12 kHz G8B08 (C) How is frequency shift related to keying speed in an FSK signal? A. The frequency shift in hertz must be at least four times the keying speed in WPM B. The frequency shift must not exceed 15 Hz per WPM of keying speed C. Greater keying speeds require greater frequency shifts D. Greater keying speeds require smaller frequency shifts G8B09 (B) What do RTTY, Morse code, PSK31 and packet communications have in common? A. They are multipath communications B. They are digital communications C. They are analog communications D. They are only for emergency communications G8B10 (B) When sending data modes, why is it important to know the duty cycle of the mode you are using? A. Your connectors, feed line or antenna may be rated for intermittent amateur service B. To prevent damage to your transmitter's final output stage due to its inability to dissipate excess heat C. To prevent blowing your power supply's fuse due to its inability to dissipate excess heat D. All of these choices are correct G8B11 (D) In what segment of the 20-meter band are most PSK31 operations found? A. At the bottom of the slow-scan TV segment, near 14.230 MHz B. At the top of the SSB phone segment, near 14.325 MHz C. In the middle of the CW segment, near 14.100 MHz D. Below the RTTY segment, near 14.070 MHz G8B12 (A) [97.303s] What is the maximum bandwidth permitted by FCC rules for amateur radio stations when operating on USB frequencies in the 60-meter band? A. 2.8 kHz B. 5.6 kHz C. +/- 2.8 kHz D. 3 kHz G8B13 (A) What is another term for the mixing of two RF signals? A. Heterodyning B. Synthesizing C. Cancellation D. Multiplying

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