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RADar > 3D155 Volume 1 URE > Flashcards

3D155 Volume 1 URE Flashcards

Learn about V1

1
Q

What is the required angle of incidence necessary to get a reflection back to a light source?

A

90 degrees

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2
Q

When a pulse of radio frequency energy is transmitted, it travels at

A

the speed of light.

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3
Q

Approximately how long does it take for radio frequency energy to travel 1 nautical mile to a target and return to the radar?

A

12.36us

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4
Q

You can identify the maximum detection range of a radar by dividing the time of one radar mile into the

A

pulse recurrence time.

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5
Q

What characteristic of frequency does a radar target moving towards the radar exhibit?

A

a higher frequency than the original broadcast.

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6
Q

Which radar subassembly ensures all circuits connected with the radar operate in a definite timed relationship?

A

synchronizer

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7
Q

What radar subassembly allows the radar system to transmit and receive from the same antenna?

A

Duplexer

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8
Q

An antenna is said to be reciprocal if

A

its transmit and receive patterns are identical.

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9
Q

Which feedhorn is used only for receiving?

A

Passive

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10
Q

One use for the beam-lobing switch of the multi-feedhorn system is to

A

Route the received signal from the number one feed horn to a dummy load.

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11
Q

What does the distribution of electromagnetic energy from the antenna over the aperture determine?

A

pattern of the antenna

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12
Q

The shape of the beam of radar energy and its antenna pattern depend on the radar’s

A

purpose.

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13
Q

The scanning method used by the radar system refers to the

A

motion of the antenna axis (of the beam) as the radar looks for an aircraft.

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14
Q

What scan is identified at the electronic countermeasure receiver by its regular intervals between illuminations?

A

Circular

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15
Q

What scan system uses a thin beam to cover a rectangular area by sweeping the area horizontally with the angle of elevation incrementally stepped up or down with each horizontal sweep of the sector?

A

raster

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16
Q

Which scan radar is also used in the acquisition phase by some airborne intercept radars?

A

raster

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17
Q

Which scan radar gets its name from the fact that each echo pulse from the aircraft being tracked yields a new azimuth and elevation correction signal?

A

monopulse

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18
Q

In which scan radar does the antenna rotate on an azimuth sweep, while the elevation angle rises slowly from 0 to 90 degrees?

A

helical

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19
Q

What causes delayed, but separate, pulses?

A

near-simultaneous reception of pulse-type information.

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20
Q

attempts to reduce multipath effects on radar tracking accuracy include the use of

A

frequency agility

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21
Q

What type of radar system uses a B-scan indicator?

A

precision approach

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22
Q

What target information is provided by a plan position indicator?

A

range and azimuth

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23
Q

In a raster scan indicator, how many vertical scan periods does it take to produce one complete picture?

A

2

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24
Q

Which indicator component produces signals that determine the overall operation of what the indicator will do?

A

data processing circuits

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25
Q

In a typical indicator system, where is digital display data from the data processing circuits converted into analog drive signals?

A

deflection circuits

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26
Q

The vacuum in a cathode-ray tube (CRT)

A

prevents collisions between electrons in the beam and air molecules.

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27
Q

What frequency is used for identification friend or foe/selective identification feature (IFF/SIF) interrogations?

A

1030 MHz

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28
Q

An X pulse is present in a selective identification feature code train when

A

the aircraft is a pilotless drone or missile.

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29
Q

Which selective identification feature special response explains a 7500 reply?

A

hijacking

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30
Q

What is the AN/UPM-155 radar test set capable of testing?

A

interrogators and associated components.

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31
Q

What possible input voltages may be supplied to the AN/UPM-155 radar test set for operation?

A

115 Vac or 230 Vac

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32
Q

What element of modulation prevents interference when sharing the same communications path is necessary?

A

channel allocation

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33
Q

What factor determines the spacing of the sidebands in an amplitude modulated signal?

A

frequency of the modulating signal

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34
Q

What is the relationship of the bandwidth required for double-sideband emitted carrier (DSBEC) amplitude modulation (AM) to the bandwidth of the modulating signal of the AM bandwidth alone?

A

twice the modulating bandwidth

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35
Q

in frequency modulation, the amount of oscillator frequency change is

A

directly proportional to the amplitude of the modulating signal.

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36
Q

A 10KHz modulating signal has enough peak voltage to cause a deviation of 30kHz. What is the modulation index?

A

3

37
Q

in phase modulation, the carrier’s

A

phase shifts at the rate of the modulating signal.

38
Q

Information capacity is increased by how many times its normal rate if using 8-phase shift keying (PSK) instead of binary PSK?

A

3

39
Q

What size bit combinations are allowed when using 16-phase shift keying?

A

4 bit

40
Q

What part of the pulse code modulation process converts a continuous time signal into a discrete time signal?

A

sampling

41
Q

By how much does non uniform quantizing and companding decreases the length of a code word?

A

11 to 7 bits

42
Q

How is the parity bit used in asynchronous transmission?

A

by the receiving device to verify that the transmission was received correctly.

43
Q

How does synchronous transmission reduce the overhead costs of data transmission?

A

blocks many characters together for transmission.

44
Q

During a vertical redundancy check, what significance does the amount of 1’s have in a data bit pattern?

A

determines parity.

45
Q

using the longitudinal redundancy check method of error correction, what does the receiver compare with the transmitter to ensure an accurate transmission of data?

A

block check character

46
Q

When used together, what two error detection methods are 98 percent effective in detecting errors?

A

vertical redundancy check and longitudinal redundancy check

47
Q

What error detection method is used for checking a data block greater than 512 and is about 99 percent effective in most applications?

A

cyclic redundancy

48
Q

when using forward error control as a method of error correction, where does error correction take place?

A

receiving end.

49
Q

which statement describes an advantage of using fiber optic cable?

A

electromagnetic fields do not affect fiber optic cables.

50
Q

which statement describes a security feature of using fiber optic cable?

A

virtually impossible to tap a fiber optic cable unnoticed.

51
Q

what type of buffer allows the fiber optic cable to be twisted or pulled with little stress on the fiber?

A

loose tube

52
Q

most fiber optic links use infrared light and consist of what frequency range?

A

750 to 1500 nm

53
Q

When considering light wave propagation, what is the name of the angle between the normal in the first material and the ray that is bounced back in the first material?

A

angle of reflection

54
Q

what is the principle on which fiber optics work?

A

total internal reflection

55
Q

what occurs because of imperfections in an optical fiber’s basic structure?

A

scattering

56
Q

what is reduced through the use of index matching fluids on fiber optic connectors?

A

fresnal reflection

57
Q

what is the most useful way to classify fiber optic cable?

A

refractive index profile and number of modes.

58
Q

what type of fiber is the least efficient, with the highest dispersion and has a core diameter range of 30um to over 800um?

A

multimode step-index

59
Q

what type of fiber has a core diameter of 50-125 micrometers (um) and consists of numerous concentric layers of glass, something like the annular rings of a tree configured to reduce dispersion?

A

multimode graded-index

60
Q

which feature of the fluke 8025A multimeter do you use to select various measurement functions?

A

rotary switch

61
Q

which feature of the fluke 8025A locks the measurement into the display for viewing and automatically updates the display when you take a new measurement?

A

touch-hold pushbutton

62
Q

which current range on the fluke 8025A do you select to measure 250 milliamps alternating current (AC)?

A

Milliamps/amp AC

63
Q

When you make a resistance measurement, how do you electrically isolate a resistor from the circuit?

A

desolder one side of the resistor?

64
Q

what is caused by low insulation resistance between conductors?

A

high-attenuation, crosstalk, and noise.

65
Q

when will insulation resistance increase?

A

thickness of the insulating material increases.

66
Q

when using the AN/PSM-2 megger, how do you apply the correct regulated output voltage?

A

turn the hand-crank at a rate to keep the indicator lights at a steady glow.

67
Q

what type of megohmmeter do you use on paper insulated conductor cable?

A

500 volt

68
Q

How many probes are normally used for an earth ground tester?

A

3

69
Q

what is the earth ground standard for communications facilities?

A

10 ohms or less

70
Q

Which mode of triggering an oscilloscope causes a trace to be drawn on the screen at all times, whether there is an input signal or not?

A

auto

71
Q

which input coupling switch position allows you to view both alternating current (AC) and direction current (DC) components of the input signal?

A

DC

72
Q

which probe lets you use the oscilloscope to measure higher voltage levels, raises the input impedance, and attenuates noise?

A

passive divider, 10:1 probe

73
Q

which probe does not need to actually make contact with the circuit under test?

A

current probe

74
Q

what digital storage oscilloscope circuit compensates for high sampling rates of high-frequency signals?

A

charged coupled device

75
Q

sampled data points are stored in the memory of a digital storage oscilloscope as

A

waveform points

76
Q

what area of a digital storage oscilloscope takes digitized samples and performs numerous manipulations on the data including measuring rise and fall times, periods, time intervals, and math computations?

A

microprocessors

77
Q

what type of sampling does a digital storage oscilloscope normally use on single shot or seldom-occurring signals?

A

real-time

78
Q

what is the frequency range of an audio signal generator?

A

20 Hz to 20kHz

79
Q

Which one of these is not an application of a radio frequency generator?

A

aligning galvanometers

80
Q

how is a radio frequency generator used?

A

align telemetry receivers

81
Q

the 10:1 power ratio represented by 1 bel can also be represented by how many decibels (dB)?

A

10dB

82
Q

what does a power reading that uses the abbreviation dBm indicate?

A

ratio of decibels relative to a 1-milliwatt standard.

83
Q

If someone says, ‘we doubled our transmitter power;’ how much is the gain in dB?

A

3 dB

84
Q

the measurable frequency and power ranges of the HP 436A power meter system are determined by the

A

selected sensor

85
Q

during what operation is the radio frequency blanking output used on the HP 436A power meter

A

during automatic zeroing

86
Q

which measurement is not made with a spectrum analyzer?

A

peak-peak voltage

87
Q

which electronic counter measurement represents the average bit to bit time of an input signal?

A

period

88
Q

which electronic counter measurement counts the number of bits in a pulse train?

A

totalize

89
Q

which are the correct four classes of electronic counters?

A

frequency, universal, microwave, and reciprocal

RADar (9 decks)

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