Radar(2018)

Question 1

What does the acronym radar mean?

Answer 1

Radio Detection and Ranging.

Question 2

What is the speed of electromagnetic energy when it travels through air?

Answer 2

Approximately the speed of light or 186,000 statute miles per second.

Question 3

What is the minimum range for a radar system with a pulsewidth of 10.5 s, which has a recovery time of 0.5 s?

Answer 3

1,804 yards.

Question 4

What is the range of target when the elapsed time for the radar pulse to travel to the target and return is 370.8 microseconds?

Answer 4

30 nautical miles.

Question 5

What factors determine the minimum range of a pulse radar system?

Answer 5

Thepulsewidthofthetransmittedpulseandtherecoverytimeoftheduplexerand the receiver.

Question 6

The maximum range of a pulse radar system depends upon what three factors?

Answer 6

Transmitted power, pulse repetition frequency (PRF), and receiver sensitivity.

Question 7

Define range resolution of a radar system.

Answer 7

Range resolution of a radar system is the minimum resolvable separation in range of two targets at the same bearing.

Question 8

What effect is achieved by increasing the length of a pulsewidth?

Answer 8

The longer the pulsewidth, the greater the range capabilities of the radar.

Question 9

What term is used to describe the situation in which atmospheric temperature first in- creases with altitude and then begins to decrease?

Answer 9

Temperature inversion.

Question 10

The bending of radar waves due to a change in density of the medium through which they are passing is known by what term?

Answer 10

Refraction.

Question 11

A very high radar antenna indicates what type of frequency?

Answer 11

A low carrier frequency.

Question 12

Radar frequency ranges are divided into sections referred to by what term?

Answer 12

Bands.

Question 13

The ideal radar pulse shape should have what characteristics?

Answer 13

A square wave with very sharp leading and trailing edges.

Question 14

What part of a radar pulse affects its range accuracy?

Answer 14

The leading edge.

Question 15

What is the reciprocal of PRF?

Answer 15

PRT

Question 16

What two RF generating devices have low interelectrode capacitance, low transit time, and the ability to handle very high levels of RF power?

Answer 16

Magnetron and klystron.

Question 17

What is the duty cycle of a radar system that has an average power of 2 Megawatts and a peak power of 200 Megawatts?

Answer 17

0.01.

Question 18

What radar transmission method does not depend on target motion or relative frequency of the returned signal?

Answer 18

Pulse modulation radar.

Question 19

What is the purpose of radar synchronizer?

Answer 19

Provides proper timing pulses to components of the radar system.

Question 20

What are the two synchronization classifications for a basic pulse radar system?

Answer 20

Self-synchronized or externally synchronized.

Question 21

What are the two high-powered RF generators used in transmitters of pulse radar systems?

Answer 21

Magnetron and klystron.

Question 22

Adding additional intermediate cavities between the input and output of a klystron has what affect on power output?

Answer 22

An increase in the power available at the output.

Question 23

What is a duplexer and what is its purpose in a radar system?

Answer 23

An electronic switch that permits the use of one antenna for both transmit and receive functions.

Question 24

What type of receiver mixes incoming signals with the receiver’s local oscillator signal to produce an intermediate frequency?

Answer 24

Superheterodyne.

Question 25

What is the purpose of the AFC circuitry within the receiver?

Answer 25

To maintain a constant IF frequency out of signal mixer.

Question 26

What function does the detector perform within the receiver?

Answer 26

Converts IF pulses into video pulses, which are applied to radar indicators.

Question 27

What are the three types of radar indicators?

Answer 27

PPI, RHI, and A-scope.

Question 28

The PPI provides what type of presentation?

Answer 28

A map-like presentation of the region scanned.

Question 29

What are the nine major components that make up a typical pulse radar system?

Answer 29

Antenna, antenna servo system, duplexer, transmitter, receiver, modulator, power supplies, synchronizer, and indicator

Question 30

What are the four positions on the SCAN SPD rotary switch on the C-10535/APS-130 Radar Set Control?

Answer 30

OFF, 25, 50, 100.

Question 31

What are the four functional groups of the T-1396/APS-130 Transmitter?

Answer 31

Power supply group, modulator group, transmitter group, and BIT group.

Question 32

What position is the DVRI located in?

Answer 32

ECMO 1.

Question 33

The CV-2434 Analog-Digital Converter is a major component of what radar system?

Answer 33

The APS-130.

Question 34

During update mode, what slew control has priority for all inputs?

Answer 34

ECMO 1.

Question 35

The acronym radar is derived from what words?

Answer 35

Radio, detection, and ranging

Question 36

Radar uses what form of energy to detect the presence of objects?

Answer 36

Electromagnetic energy

Question 37

RF energy travels through air at approximately what speed?

Answer 37

186,000 statute miles per second 162,000 nautical miles per second 300 million meters per second

Question 38

What is the time required for two-way travel of an RF pulse if the target is 15 miles from the radar unit?

Answer 38

185.4 μs

Question 39

An increase in recovery time of a radar set will cause which of the following results?

Answer 39

Increase in minimum range and decrease in receiver sensitivity

Question 40

A radar set has a pulsewidth of 3 μs. In order for the operator to see two separate blips that are directly on the same line of bearing, what minimum distance must separate the targets?

Answer 40

492 yards

Question 41

Apulse radar’s range resolution is a function of the transmitted pulsewidth, while azimuth resolution is a function of what?

Answer 41

Antenna beamwidth

Question 42

In order for two targets at the same range to appear as two targets instead of one target on the radar’s indicator, what minimum distance must separate the two targets?

Answer 42

One beamwidth

Question 43

The maximum power of a RF transmitted pulse is referred to by what term?

Answer 43

Peak power

Question 44

Radar performance is affected by which of the following factors?

Answer 44

- Prevailing atmospheric conditions - The quality of maintenance performed on the equipment - The operator’s knowledge of the equipment’s capability

Question 45

Although high-frequency energy from a transmitter travels essentially in a straight line and a constant speed, refraction and speed change are known to occur. Which of the following atmospheric conditions cause this to happen?

Answer 45

Temperature, pressure, and vapor content

Question 46

Which of the following conditions is formed by a temperature inversion and/or by a moisture lapse that may extend or reduce the range of radar?

Answer 46

Ducting

Question 47

The elapsed time between the start of one transmitted pulse and the start of the next is known as which of the following terms?

Answer 47

PRT

Question 48

In addition to certain power considerations, the output pulse of a radar transmitter should possess which of the following characteristic shapes in order to present nearby targets on an indicator?

Answer 48

Narrow with a sloping trailing edge

Question 49

Generally, the maximum range of pulse type radar is determined by what element

Answer 49

Pulse repetition frequency

Question 50

The PRF of a radar must be low enough to eliminate ambiguous targets, but high enough that the antenna’s speed of rotation does not interfere with what factor?

Answer 50

The transmitted frequency

Question 51

A radar set with a PRF of 2,000 PPS and an antenna rotation of 20 rpm produces what maximum number of pulses per degree?

Answer 51

16.6

Question 52

Which of the following statements is correct concerning peak power and average power of a pulsed radar system?

Answer 52

Peak power is expended during the transmission of a pulse, and average power is the power expended over the pulse repetition time

Question 53

Which of the following formulas expresses the duty cycle of a radar set?

Answer 53

PW x PRF

Question 54

Which of the following methods of transmitting RF energy uses the Doppler principle for radar detection?

Answer 54

Continuous-wave

Question 55

Frequency-modulated radars transmit a wave that is continuously varying from a fixed reference frequency. When frequency modulation is used, how is the target detected?

Answer 55

Comparing the frequency of the signal that is presently being transmitted with the received frequency that has been reflected from the target

Question 56

Continuous-wave radar, which employs the Doppler effect, is best suited in detecting which of the following targets?

Answer 56

Targets with a high degree of bearing resolution

Question 57

Which of the following components of a radar system determines the timing for all components of the radar?

Answer 57

Synchronizer

Question 58

What is the purpose of the modulator in a typical pulse radar system?

Answer 58

To supply high voltage, rectangular pulses | to drive the transmitter

Question 59

What modulator circuitry determines the voltage level and width of the pulse generated?

Answer 59

The pulse forming network

Question 60

Which of the following tubes should be used as the power amplifier in a radar transmitter?

Answer 60

Klystron

Question 61

The process whereby some electrons are accelerated, some are decelerated, and others are unaffected in the movement of the electron beam towards the collector end of a klystron is referred to by what term?

Answer 61

Bunching

Question 62

What is the primary function of radar duplexing system?

Answer 62

To permit the use of one antenna for | transmission and reception

Question 63

A defective duplexer will likely cause damage to which of the following radar components?

Answer 63

The receiver

Question 64

Because of the difficulty in amplifying high-frequency signals received in most radar receivers, it is necessary to generate an intermediate-frequency signal by a process referred to by which of the following terms?

Answer 64

Heterodyning

Question 65

The Azimuth Elevation Range Indicator IP-1060A/APQ-148 is located at what station?

Answer 65

ECMO 1

Question 66

How many slew controls are there with the APS-130 radar system?

Answer 66

2

Question 67

What are the four ranges on the PPI RNG rotary switch on the RCP?

Answer 67

15, 30, 75, 150

Question 68

The Radar Set Control C-10535/APS-130 (RCP) is located at which of the following stations?

Answer 68

ECMO 1

Question 69

The intermediate frequency is produced in what stage of a microwave receiver?

Answer 69

Signal mixer

Question 70

What section of a radar receiver usually determines the overall bandwidth?

Answer 70

IF amplifier/detector

Question 71

The IF amplifier stages of a radar receiver determines which of the following receiver characteristics?

Answer 71

- The gain - Signal-to-noise ratio - Converts IF pulses to video pulses

Question 72

Which of the following radar displays provides a map-like presentation that is practically an exact replica of the region scanned by the radar antenna?

Answer 72

PPI

Question 73

On a RHI display, what is represented by the vertical axis?

Answer 73

Elevation

Question 74

On an A-scope presentation, what is displayed on the horizontal axis?

Answer 74

Range only

Question 75

Which component provides a crystalcontrolled clock and digital timing loop to generate PRF trigger, sweep triggers, range markers, and precision range line signal?

Answer 75

RSG