Скачать или смотреть 14. G3B – Maximum Usable Frequency; Lowest Usable Frequency;

G3B – Maximum Usable Frequency; Lowest Usable Frequency; short path and long path propagation;
determining propagation conditions; ionospheric refraction
G3B01 (D)
What is a characteristic of skywave signals arriving at your location by both short-path and long-path
propagation?
A. Periodic fading approximately every 10 seconds
B. Signal strength increased by 3 dB
C. The signal might be cancelled causing severe attenuation
D. A slightly delayed echo might be heard
~~
G3B02 (D)
What factors affect the MUF?
A. Path distance and location
B. Time of day and season
C. Solar radiation and ionospheric disturbances
D. All these choices are correct
~~
G3B03 (A)
Which frequency will have the least attenuation for long-distance skip propagation?
A. Just below the MUF
B. Just above the LUF
C. Just below the critical frequency
D. Just above the critical frequency
~~
G3B04 (A)
Which of the following is a way to determine current propagation on a desired band from your station?
A. Use a network of automated receiving stations on the internet to see where your transmissions are being
received
B. Check the A-index
C. Send a series of dots and listen for echoes
D. All these choices are correct
~~G3B05 (A)
How does the ionosphere affect radio waves with frequencies below the MUF and above the LUF?
A. They are refracted back to Earth
B. They pass through the ionosphere
C. They are amplified by interaction with the ionosphere
D. They are refracted and trapped in the ionosphere to circle Earth
~~
G3B06 (C)
What usually happens to radio waves with frequencies below the LUF?
A. They are refracted back to Earth
B. They pass through the ionosphere
C. They are attenuated before reaching the destination
D. They are refracted and trapped in the ionosphere to circle Earth
~~
G3B07 (A)
What does LUF stand for?
A. The Lowest Usable Frequency for communications between two specific points
B. Lowest Usable Frequency for communications to any point outside a 100-mile radius
C. The Lowest Usable Frequency during a 24-hour period
D. Lowest Usable Frequency during the past 60 minutes
~~
G3B08 (B)
What does MUF stand for?
A. The Minimum Usable Frequency for communications between two points
B. The Maximum Usable Frequency for communications between two points
C. The Minimum Usable Frequency during a 24-hour period
D. The Maximum Usable Frequency during a 24-hour period
~~
G3B09 (C)
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the F2
region?
A. 180 miles
B. 1,200 miles
C. 2,500 miles
D. 12,000 miles
~~
G3B10 (B)
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the E
region?
A. 180 miles
B. 1,200 miles
C. 2,500 miles
D. 12,000 miles~~
G3B11 (A)
What happens to HF propagation when the LUF exceeds the MUF?
A. Propagation via ordinary skywave communications is not possible over that path
B. HF communications over the path are enhanced
C. Double-hop propagation along the path is more common
D. Propagation over the path on all HF frequencies is enhanced
~~
G3B12 (D)
Which of the following is typical of the lower HF frequencies during the summer?
A. Poor propagation at any time of day
B. World-wide propagation during daylight hours
C. Heavy distortion on signals due to photon absorption
D. High levels of atmospheric noise or static
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