3D155 Volume 1 URE

Question 1

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

Answer 1

90 degrees

Question 2

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

Answer 2

the speed of light.

Question 3

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

Answer 3

12.36us

Question 4

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

Answer 4

pulse recurrence time.

Question 5

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

Answer 5

a higher frequency than the original broadcast.

Question 6

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

Answer 6

synchronizer

Question 7

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

Answer 7

Duplexer

Question 8

An antenna is said to be reciprocal if

Answer 8

its transmit and receive patterns are identical.

Question 9

Which feedhorn is used only for receiving?

Answer 9

Passive

Question 10

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

Answer 10

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

Question 11

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

Answer 11

pattern of the antenna

Question 12

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

Answer 12

purpose.

Question 13

The scanning method used by the radar system refers to the

Answer 13

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

Question 14

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

Answer 14

Circular

Question 15

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?

Answer 15

raster

Question 16

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

Answer 16

raster

Question 17

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?

Answer 17

monopulse

Question 18

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

Answer 18

helical

Question 19

What causes delayed, but separate, pulses?

Answer 19

near-simultaneous reception of pulse-type information.

Question 20

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

Answer 20

frequency agility

Question 21

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

Answer 21

precision approach

Question 22

What target information is provided by a plan position indicator?

Answer 22

range and azimuth

Question 23

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

Answer 23

2

Question 24

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

Answer 24

data processing circuits

Question 25

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

Answer 25

deflection circuits

Question 26

The vacuum in a cathode-ray tube (CRT)

Answer 26

prevents collisions between electrons in the beam and air molecules.

Question 27

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

Answer 27

1030 MHz

Question 28

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

Answer 28

the aircraft is a pilotless drone or missile.

Question 29

Which selective identification feature special response explains a 7500 reply?

Answer 29

hijacking

Question 30

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

Answer 30

interrogators and associated components.

Question 31

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

Answer 31

115 Vac or 230 Vac

Question 32

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

Answer 32

channel allocation

Question 33

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

Answer 33

frequency of the modulating signal

Question 34

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?

Answer 34

twice the modulating bandwidth

Question 35

in frequency modulation, the amount of oscillator frequency change is

Answer 35

directly proportional to the amplitude of the modulating signal.

Question 36

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

Answer 36

3

Question 37

in phase modulation, the carrier's

Answer 37

phase shifts at the rate of the modulating signal.

Question 38

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

Answer 38

3

Question 39

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

Answer 39

4 bit

Question 40

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

Answer 40

sampling

Question 41

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

Answer 41

11 to 7 bits

Question 42

How is the parity bit used in asynchronous transmission?

Answer 42

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

Question 43

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

Answer 43

blocks many characters together for transmission.

Question 44

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

Answer 44

determines parity.

Question 45

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

Answer 45

block check character

Question 46

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

Answer 46

vertical redundancy check and longitudinal redundancy check

Question 47

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

Answer 47

cyclic redundancy

Question 48

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

Answer 48

receiving end.

Question 49

which statement describes an advantage of using fiber optic cable?

Answer 49

electromagnetic fields do not affect fiber optic cables.

Question 50

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

Answer 50

virtually impossible to tap a fiber optic cable unnoticed.

Question 51

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

Answer 51

loose tube

Question 52

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

Answer 52

750 to 1500 nm

Question 53

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?

Answer 53

angle of reflection

Question 54

what is the principle on which fiber optics work?

Answer 54

total internal reflection

Question 55

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

Answer 55

scattering

Question 56

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

Answer 56

fresnal reflection

Question 57

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

Answer 57

refractive index profile and number of modes.

Question 58

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

Answer 58

multimode step-index

Question 59

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?

Answer 59

multimode graded-index

Question 60

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

Answer 60

rotary switch

Question 61

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?

Answer 61

touch-hold pushbutton

Question 62

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

Answer 62

Milliamps/amp AC

Question 63

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

Answer 63

desolder one side of the resistor?

Question 64

what is caused by low insulation resistance between conductors?

Answer 64

high-attenuation, crosstalk, and noise.

Question 65

when will insulation resistance increase?

Answer 65

thickness of the insulating material increases.

Question 66

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

Answer 66

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

Question 67

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

Answer 67

500 volt

Question 68

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

Answer 68

3

Question 69

what is the earth ground standard for communications facilities?

Answer 69

10 ohms or less

Question 70

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?

Answer 70

auto

Question 71

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

Answer 71

DC

Question 72

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

Answer 72

passive divider, 10:1 probe

Question 73

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

Answer 73

current probe

Question 74

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

Answer 74

charged coupled device

Question 75

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

Answer 75

waveform points

Question 76

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?

Answer 76

microprocessors

Question 77

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

Answer 77

real-time

Question 78

what is the frequency range of an audio signal generator?

Answer 78

20 Hz to 20kHz

Question 79

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

Answer 79

aligning galvanometers

Question 80

how is a radio frequency generator used?

Answer 80

align telemetry receivers

Question 81

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

Answer 81

10dB

Question 82

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

Answer 82

ratio of decibels relative to a 1-milliwatt standard.

Question 83

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

Answer 83

3 dB

Question 84

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

Answer 84

selected sensor

Question 85

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

Answer 85

during automatic zeroing

Question 86

which measurement is not made with a spectrum analyzer?

Answer 86

peak-peak voltage

Question 87

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

Answer 87

period

Question 88

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

Answer 88

totalize

Question 89

which are the correct four classes of electronic counters?

Answer 89

frequency, universal, microwave, and reciprocal