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