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2015 > MOD 17 1,2,3 > Flashcards

MOD 17 1,2,3 Flashcards

1
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A
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2
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Q1. What are the two types of electrical communications?

A

A1. Radio and wire.

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3
Q

Q2. What is the main advantage of radiotelegraph communications?

A

Reliability

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4
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Q3. Why is radiotelephone one of the most useful methods of military communications?

A

A3. It is direct, convenient and easy to use.

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5
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Q4. What are the disadvantages of radiotelephone communications?

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A4. Static, enemy interference or a high local noise level.

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6
Q

Q5. What is the main use of a radio teletypewriter?

A

A5. High speed automatic communications across ocean areas.

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7
Q

Q6. What is facsimile?

A

A6. The process used to transmit photographs, charts and other graphic information electronically.

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8
Q

Q7. A system is subdivided into what levels?

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A7. Set, group, unit, assembly, subassembly, and part.

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9
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Q8. In the example 1A6CR3, what is the assembly designator?

A

A6

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10
Q

Q9. he majority of vlf transmitters are used for what purpose?

A

A9. Fleet communications or navigation.

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11
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Q10. Today the Navy uses lf communications as a segment of what operational system?

A

A10. Fleet Multichannel Broadcast System.

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12
Q

Q11. Why does the Navy only use the upper and lower ends of the mf band?

A

A11. Due to the commercial broadcast (AM) band.

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13
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Q12. What are the four general types of communications services in the hf band?

A

A12. Point-to-point, ship-to-shore, ground-to-air, and fleet broadcast.

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14
Q

A message transmitted on several frequencies at the same time is an example of what type of transmission?

A

A13. Frequency-diversity.

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15
Q

Q14. Physically separating receive antennas is an example of what technique?

A

A14. Space-diversity.

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16
Q

Q15. When using frequencies above 30 megahertz, you are normally limited to using what range?

A

A15. Line of sight.

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17
Q

Q16. The naval communications system is made up of what two groups of communications?

A

A16. Strategic and tactical.

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18
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Q17. What are the five most prominent communications modes of operation?

A

A17. Simplex, half-duplex, semiduplex, duplex, and broadcast.

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19
Q

Q18. What four switched networks are part of the defense communications system?

A

A18. AUTOVON, AUTOSEVOCOM, AUTODIN, and DSSCS.

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20
Q

Q19. What two elements support only designated Navy requirements?

A

A19. HICOM and NORATS.

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21
Q

Q1. What are the four basic transmitter types?

A

A1. Am, fm, cw, ssb.

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22
Q

Q2. What is the function of the oscillator in a cw transmitter?

A

A2. It generates an rf carrier at a given frequency within required limits.

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23
Q

Q3. What is the final stage of a transmitter?

A

A3. Power amplifier.

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24
Q

Q4. What purpose does a microphone perform in an AM transmitter?

A

A4. It converts audio (sound) into electrical energy.

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25
Q

Q5. In an fm transmitter, when does an oscillator generate only a steady frequency?

A

A5. When no modulation is present.

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26
Q

Q6. What is a harmonic?

A

A6. It is an exact multiple of the basic or fundamental frequency.

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27
Q

Q7. If the fundamental frequency is 200 megahertz, what is the third harmonic?

A

A7. 600 megahertz.

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28
Q

Q8. Why are frequency multipliers used?

A

A8. To obtain higher carrier frequencies.

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29
Q

Q9. What are two advantages of ssb transmission?

A

A9. It saves power and frequency bandwidth.

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30
Q

Q10. What is the purpose of an order-wire circuit?

A

A10. For operator-to-operator service messages and frequency changes.

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31
Q

Q11. What four basic functions must a receiver perform?

A

A11. Reception, selection, detection, and reproduction.

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32
Q

Q12. What are the four basic receiver characteristics?

A

A12. Sensitivity, noise, selectivity, and fidelity.

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33
Q

Q13. What frequency conversion principle is used to develop the IF?

A

A13. Heterodyning.

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34
Q

Q14. What is the function of the detector?

A

A14. To extract the modulating audio signal.

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35
Q

Q15. What is the major disadvantage of an fm signal as compared to an AM signal?

A

A15. Wide bandpass.

36
Q

Q16. What two components give a ssb receiver its advantages over an AM superheterodyne receiver?

A

A16. A special type of detector and a carrier reinsertion oscillator.

37
Q

Q17. What does manual gain control do to strong and weak signals, respectively?

A

A17. Attenuates the strong and amplifies the weak.

38
Q

Q18. What is the purpose of agc/avc in a receiver?

A

A18. To limit unwanted variations in the output.

39
Q

Q19. What is a disadvantage of agc?

A

A19. Weak signals produce bias, which could result in no usable receiver output.

40
Q

Q20. What is the main difference between agc and dagc?

A

A20. Dagc does not attenuate weak signals.

41
Q

Q21. What is the function of the bfo?

A

A21. It is heterodyned with the rf to produce an audio frequency.

42
Q

Q22. What is the purpose of a squelch circuit?

A

A22. It eliminates noise when no signal is being received.

43
Q

Q23. What does a tone control circuit in a receiver do to the audio signal?

A

A23. It controls the amount of bass and treble response.

44
Q

Q24. What is the function of a crystal filter in a receiver?

A

A24. It is used to achieve maximum selectivity.

45
Q

Q25. What is the primary function of an afc circuit?

A

A25. It is used to accurately control the frequency of the oscillator.

46
Q

Q26. What is frequency synthesis?

A

A26. The process of selecting and/or heterodyning frequencies to produce a signal frequency.

47
Q

Q1. What are the basic functions of a handset?

A

To convert energy electrical/acoustic to acoustic/electrical and to key/unkey a transmitter. Also it mutes a receiver when transmitting

48
Q

Q2. What capability does a transmitter transfer switchboard provide?

A

A2. Transferring remote control functions and signals to transmitters.

49
Q

Q3. What function does a receiver transfer switchboard perform?

A

A3. Transfers receiver audio outputs to remote control stations.

50
Q

Q4. If the rf amplifier discussed has an 80 milliwatt input, what would be the maximum output?

A

A4. 800 watts.

51
Q

Q5. What are the tuning modes for the coupler group discussed?

A

A5. Automatic, semiautomatic, and manual.

52
Q

Q6. What is the purpose of an antenna coupler?

A

A6. It matches the impedance of an antenna to that of a transmission line at any desired frequency.

53
Q

Q7. Why is the coupler pressurized with nitrogen?

A

A7. To aid in heat transfer and prevent corona and arcing.

54
Q

Q8. What are the transmitter operating modes?

A

A8. Lsb, usb, isb, AM, cw, fsk.

55
Q

Q9. What type of tuning does the receiver use?

A

Digital

56
Q

Q10. What is the function of an antenna patch panel?

A

A10. To connect an antenna/transmission line to a receiver/transmitter.

57
Q

Q11. What are the functions of a multicoupler?

A

. Patching and filtering and permits the multiple use of receivers and/or transmitters on a single antenna.

58
Q

Q12. What are the terms used to describe an open or closed telegraph circuit?

A

A12. Space and mark.

59
Q

Q13. How many units are in a tty signal and what are they?

A

A13. Intelligence (5), start (1), stop (1).

60
Q

There are not enough combinations of the five-unit code to handle the alphabet, symbols and so forth. What is used to increase the number of available code combinations?

A

A14. Shift signals.

61
Q

Q15. What are the two teletypewriter modes of operation?

A

A15. Synchronous and nonsynchronous.

62
Q

Q16. Define baud.

A

A16. A unit of modulation rate.

63
Q

Q17. Define bit.

A

A17. Binary digit.

64
Q

Q18. What are the two types of dc operations used to represent mark and space conditions?

A

A18. Neutral and polar.

65
Q

Q19. What is the function of a keyer?

A

A19. Converts dc to corresponding mark and space modulation.

66
Q

Q20. What is the function of a converter?

A

A20. Converts the audio signal to dc pulses.

67
Q

Q21. Basically describe an afts system.

A

A21. Uses AM to change dc to audio.

68
Q

Q22. Basically describe an rfcs system.

A

A22. A keyer provides rf excitation, which can be shifted above or below the assigned frequency.

69
Q

Q23. Most Navy tty sets operate at what speeds?

A

A23. 60, 75, or 100 wpm.

70
Q

Q24. A receive tty set provides outputs in what formats?

A

A24. Page-size copy paper and perforated tape.

71
Q

Q25. What does the color red indicate on a tty patch panel?

A

A25. It handles classified information.

72
Q

Q26. What are the functions of cryptographic equipment?

A

A26. To code or decode messages.

73
Q

Q27. What are the functions of a converter-comparator group?

A

The comparator compares the signal strengths from the receivers and the converter converts the frequency-shift rf signal into a tty set dc loop control signal.

74
Q

Q28. What is the function of a tone terminal set?

A

A28. It converts dc to audio or vice versa.

75
Q

Q29. What are the two types of multiplexing?

A

A29. Time-division and frequency-division.

76
Q

Q30. What is the purpose of multiplexing?

A

A30. It allows simultaneous transmission of multiple signals on a single transmission path.

77
Q

Q31. The transmission of still images over an electrical communications system is known as what?

A

Facsimile

78
Q

Q32. The term TEMPEST refers to what?

A

A32. Compromising emanations.

79
Q

Q33. What are the three fundamental requirements of a military communications system?

A

A33. Reliability, security, and speed.

80
Q

Q34. Which of the above requirements is most important?

A

Reliability

81
Q

Q35. What is the purpose of QMCS?

A

A35. To ensure continuous, optimum performance of communications systems.

82
Q

Q36. What is emi?

A

A36. Electromagnetic interference.

83
Q

Q37. What are the two emi transmission methods?

A

A37. Conduction and radiation.

84
Q

Q38. Electromagnetic radiation is hazardous to personnel in what two ways?

A

A38. Rf burns and biological, thermal, and neurological effects.

85
Q

Q39. What is the most useful and widespread technique to reduce rf burn hazards?

A

A39. Proper bonding and grounding.

2015 (12 decks)

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