Vol2 URE2 CDC 3D153

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This is a URE #2 for CDC 3D153 and is to be used as a study aid for the RF transmission systems CDC's.

Questions and Answers

1.

(213) Direct waves are radio waves that travel
- A.
  
  Long distances with few interruptions
- B.
  
  From point to point along the earth’s surface
- C.
  
  Through the air in a straight line.
- D.
  
  No more than 20 miles to the receive antenna
Correct Answer
C. Through the air in a straight line.
2.

(213) Radio waves that travel near the earth’s surface are called
- A.
  
  Earth waves
- B.
  
  Global waves
- C.
  
  Ground waves
- D.
  
  Terrestrial waves
Correct Answer
C. Ground waves
3.

(213) Sky wave transmission is used for which type of communications?
- A.
  
  Long distance
- B.
  
  Subterrestrial
- C.
  
  Atmospheric
- D.
  
  Line of sight
Correct Answer
A. Long distance
4.

(214) Which gives sky wave propagation its ability to communicate beyond the optical line-of sight (LOS)?
- A.
  
  Refraction
- B.
  
  Reflection
- C.
  
  Earth's conductivity
- D.
  
  Atmospheric charge
Correct Answer
A. Refraction
5.

(214) Which gives sky wave propagation its ability to communicate beyond the optical line-ofsight (LOS)?
- A.
  
  Refraction
- B.
  
  Reflection
- C.
  
  Earth's conductivity
- D.
  
  Atmospheric change
Correct Answer
A. Refraction
6.

(214) Frequencies higher than the critical frequency are?
- A.
  
  Returned to earth
- B.
  
  Passed into space
- C.
  
  The most desirable
- D.
  
  Refracted by the F2 layer
Correct Answer
B. Passed into space
7.

(214) In high frequency (HF) communications, the lowest frequency that arrives at the distant receiver on 90 percent of the undisturbed days of the month is called the?
- A.
  
  Maximum usable frequency (MUF)
- B.
  
  Lowest usable frequency (LUF)
- C.
  
  Operating frequency
- D.
  
  Critical frequency
Correct Answer
B. Lowest usable frequency (LUF)
8.

(214) The abbreviation FOT is derived from the term?
- A.
  
  Outbound traffic frequency
- B.
  
  Optimum tropospheric frequency
- C.
  
  Frequency of optimum transmission
- D.
  
  Frequency of outbound frequency
Correct Answer
C. Frequency of optimum transmission
9.

(214) Magneton splitting creates two waves called?
- A.
  
  Direct and indirect
- B.
  
  Ordinary and abnormal
- C.
  
  In-phase and out-of-phase
- D.
  
  Ordinary and extraordinary
Correct Answer
D. Ordinary and extraordinary
10.

(214) What occurs when a transmitted signal travels over two or more separate paths during transmission?
- A.
  
  Skip effects
- B.
  
  Modulation
- C.
  
  Multipathing
- D.
  
  Magneton splitting
Correct Answer
C. Multipathing
11.

(215) Which layer of the ionosphere is most important to high frequency (HF) communications?
- A.
  
  D
- B.
  
  E
- C.
  
  F
- D.
  
  Topside
Correct Answer
C. F
12.

(215) During what season do we have the wider range of critical frequencies and less absorption of all frequencies?
- A.
  
  Fall
- B.
  
  Winter
- C.
  
  Spring
- D.
  
  Summer
Correct Answer
B. Winter
13.

(215) What is the recombination process dependent upon?
- A.
  
  Season
- B.
  
  Time of day
- C.
  
  Regular variation
- D.
  
  Irregular variations
Correct Answer
B. Time of day
14.

(215) Sunspots are disturbances?
- A.
  
  In the sun's atmosphere
- B.
  
  On the sun's surface
- C.
  
  In the ionosphere
- D.
  
  Beneath the sun's surface
Correct Answer
B. On the sun's surface
15.

(216) For communications purposes, the usable frequency spectrum ranges from?
- A.
  
  3Hz to 300 GHz+
- B.
  
  300 Hz to 3000 GHz
- C.
  
  3000 Hz to 3000 GHz
- D.
  
  30 MHz to 300 MHz
Correct Answer
A. 3Hz to 300 GHz+
16.

(216) What U.S. government agency divides the radio frequency (RF) spectrum into different bands?
- A.
  
  Federal Aviation Agency
- B.
  
  American National Standard Institute
- C.
  
  Federal Communications Commission
- D.
  
  Institute of Electrical & Electronics Engineers, INC
Correct Answer
C. Federal Communications Commission
17.

(217) Near-vertical-incidence sky (NVIS) wave operations are most effective when you’re using?
- A.
  
  Lower high frequency (HF) frequencies
- B.
  
  Higher HF frequencies
- C.
  
  Medium HF frequencies
- D.
  
  Low takeoff antenna angles
Correct Answer
A. Lower high frequency (HF) frequencies
18.

(217) What frequency band is most susceptible to jamming?
- A.
  
  Low frequency
- B.
  
  Medium frequency
- C.
  
  High Frequency
- D.
  
  Very High Frequency
Correct Answer
C. High Frequency
19.

(217) What frequency bands doe the MILSTAR satellite system use?
- A.
  
  High frequency (HF) and Ultra high Frequency (UHF)
- B.
  
  Super-High Frequency (SHF) and Extremely high frequency (EHF)
- C.
  
  Very high frequency (VHF) and SHF
- D.
  
  VHF and UHF
Correct Answer
B. Super-High Frequency (SHF) and Extremely high frequency (EHF)
20.

(218) The main very high frequency (VHF) Ultra high frequency (UHF) communications emphasis is on?
- A.
  
  Long range deployable communications
- B.
  
  Short range fixed communications
- C.
  
  Emergency communications
- D.
  
  Air-ground communications
Correct Answer
D. Air-ground communications
21.

(219) Super high frequency (SHF)/extremely high frequency (EHF) range is limited to?
- A.
  
  Scattering
- B.
  
  Line-of-sight (LOS)
- C.
  
  Earth's conductivity
- D.
  
  Atmospheric absorption
Correct Answer
B. Line-of-sight (LOS)
22.

(220) In a move to overcome the limited range of forward propagation by tropospheric scatter (FPTS) without requiring many costly relay systems, what was developed?
- A.
  
  Optical horizon radar
- B.
  
  Satellite communications
- C.
  
  Microwave communications
- D.
  
  Line-of-sight (LOS) communication
Correct Answer
B. Satellite communications
23.

(220) Why isn’t very high frequency (VHF) normally used for satellite communications?
- A.
  
  The frequency is too low
- B.
  
  The frequency is too high
- C.
  
  Ionospheric refraction can occur
- D.
  
  The rate of absorption is too great
Correct Answer
A. The frequency is too low
24.

(220) When comparing the radio and optical horizons, which one is farther away and by what percent?
- A.
  
  Optical; 15
- B.
  
  Radio; 15
- C.
  
  Optical; 33
- D.
  
  Radio; 33
Correct Answer
B. Radio; 15
25.

(220) When K is greater than 4/3, the radio horizon will?
- A.
  
  Decrease, then increase.
- B.
  
  Remain the same
- C.
  
  Decrease
- D.
  
  Increase
Correct Answer
D. Increase
26.

(220) A radio wave originated at a center source in free space. If the field strength at one mile from the source has a field strength of 100 microvolts per meter, what is the field strength at two miles?
- A.
  
  25 microvolts per metear
- B.
  
  50 microvolts per meter
- C.
  
  100 microvolts per meter
- D.
  
  200 microvolts per meter
Correct Answer
B. 50 microvolts per meter

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Current Version
Mar 20, 2022

Quiz Edited by
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Aug 20, 2012

Quiz Created by
Jayhuiz23

Vol2 Ure2 CDC 3D153

(213) Direct waves are radio waves that travel

(213) Radio waves that travel near the earth’s surface are called

(213) Sky wave transmission is used for which type of communications?

(214) Which gives sky wave propagation its ability to communicate beyond the optical line-of sight (LOS)?

(214) Which gives sky wave propagation its ability to communicate beyond the optical line-ofsight (LOS)?

(214) Frequencies higher than the critical frequency are?

(214) In high frequency (HF) communications, the lowest frequency that arrives at the distant receiver on 90 percent of the undisturbed days of the month is called the?

(214) The abbreviation FOT is derived from the term?

(214) Magneton splitting creates two waves called?

(214) What occurs when a transmitted signal travels over two or more separate paths during transmission?

(215) Which layer of the ionosphere is most important to high frequency (HF) communications?

(215) During what season do we have the wider range of critical frequencies and less absorption of all frequencies?

(215) What is the recombination process dependent upon?

(215) Sunspots are disturbances?

(216) For communications purposes, the usable frequency spectrum ranges from?

(216) What U.S. government agency divides the radio frequency (RF) spectrum into different bands?

(217) Near-vertical-incidence sky (NVIS) wave operations are most effective when you’re using?

(217) What frequency band is most susceptible to jamming?

(217) What frequency bands doe the MILSTAR satellite system use?

(218) The main very high frequency (VHF) Ultra high frequency (UHF) communications emphasis is on?

(219) Super high frequency (SHF)/extremely high frequency (EHF) range is limited to?

(220) In a move to overcome the limited range of forward propagation by tropospheric scatter (FPTS) without requiring many costly relay systems, what was developed?

(220) Why isn’t very high frequency (VHF) normally used for satellite communications?

(220) When comparing the radio and optical horizons, which one is farther away and by what percent?

(220) When K is greater than 4/3, the radio horizon will?

(220) A radio wave originated at a center source in free space. If the field strength at one mile from the source has a field strength of 100 microvolts per meter, what is the field strength at two miles?