Fc/et A-School Ap Radar

Front 1

What does RADAR stand for?

Back 1

Radio detection and ranging.

Front 2

What is the purpose of RADAR?

Back 2

Radar systems use reflected radio frequency(RF) pulses to determine the presence, direction to, height of, and distance of detected objects or targets.

Front 3

What is azimuth, altitude, and range expressed in?

Back 3

Azimuth is expressed in degrees, altitude is expressed in feet, and range is expressed in nautical miles.

Front 4

What are the four transmission methods?

Back 4

Pulse Modulation, Frequency Modulation, Continuous Wave, and Pulse Doppler.

Front 5

What is the reference coordinate used to describe the surface of the Earth, represented by an imaginary flat plane which is tangent (or parallel) to the Earth's surface at that location?

Back 5

The horizontal plane.

Front 6

What is the reference coordinate used to describe the angle between the horizontal plane and the line-of-sight, measured in the vertical plane?

Back 6

The elevation angle.

Front 7

What is true bearing?

Back 7

The angle between true north and the line-of-sight, measured clockwise in the horizontal plane.

Front 8

True or False. Most radar systems use some variation of a pulse doppler type transmission method.

Back 8

False, most radar systems use some variation of a pulse type transmission method.

Front 9

What are the six basic components that make up a pulse radar system?

Back 9

Power supply, Synchronizer/Modulator, Transmitter, Antenna/Duplexer, Reciever, and Indicator.

Front 10

What is relative bearing?

Back 10

The angle between the vertical plane, running down the center of own ship and the line-of-sight, measured clockwise in the horizontal plane.

Front 11

Why is the transmitter dangerous?

Back 11

The transmitter produces very high voltages, current, and microwave radiation levels that are extremely dangerous.

Front 12

What controls the radar pulse width by the use of a rectangular DC pulse of the required duration and amplitude?

Back 12

The Synchronizer/Modulator.

Front 13

True or False. The duplexer defines the beam shape.

Back 13

False, the antenna defines the beam shape.

Front 14

True or False. The antenna system includes the antenna, transmission lines, the waveguide from the transmitter to the antenna, and the transmission lines and waveguide from the antenna to the reciever.

Back 14

True.

Front 15

What is a duplexer and what is its purpose?

Back 15

A duplexer is essentially an electronic switch that permits a radar system to use a single antenna to both transmit and receive. Its purpose is to protect the receiver from the high power output of the transmitter.

Front 16

What provides the necessary voltages for the radar system?

Back 16

The power supply.

Front 17

True or False. The indicator is the primary operator interface for the radar system.

Back 17

True.

Front 18

True or False. 3-dimensional radars detect range, bearing, and height.

Back 18

True.

Front 19

True or False. 2-dimensional radars detect range and bearing only.

Back 19

True.

Front 20

What types of radar are classified as 2-D?

Back 20

Search(air and surface), navigation, and airborne.

Front 21

What types of radar are classified as 3-D?

Back 21

Fire control, approach, height finding, and airborne.

Front 22

What type of radar has good range and bearing resolution and is normally short range surface search radar?

Back 22

Navigation radar.

Front 23

What are the three phases of fire-control radar?

Back 23

Designation phase, acquisition phase, and tracking phase.

Front 24

What limits the range of surface search radars?

Back 24

The radar horizon.

Front 25

What radar is used for initial detection of targets?

Back 25

Search radar.

Front 26

What are the characteristics of air search radars?

Back 26

High peak power, low pulse repetition rate, and wide pulse width.

Front 27

What is the difference between ground-controlled approach radar and carrier-controlled approach radar?

Back 27

Carrier-controlled approach radar is more sophisticated due to the movements of the ship and the more complicated landing environment.

Front 28

True or False. Altitude of height-finding radars use a wide beam width in the vertical plane.

Back 28

False, Altitude or height-finding radars use a narrow beam in the vertical plane.

Front 29

What is another name for fire-control radar?

Back 29

Tracking radar.

Front 30

True or False. The accuracy of the fire-control radar is due to its very narrow, circular beam.

Back 30

True.

Front 31

What are the characteristics of the fire-control radar?

Back 31

High pulse repetition rate, very narrow pulse width, and very narrow beam width.

Front 32

What is the difference between a passive homing missile and an active homing missile?

Back 32

Active homing missiles contain a radar system on board that illuminates the target. Passive missiles use the ship to paint the target.

Front 33

What does the planned position indicator display?

Back 33

Bearing and range.

Front 34

How far does RF travel in one microsecond?

Back 34

328 yards.

Front 35

What is the formula for range?

Back 35

Range equals elapsed time divided by 12.36 microseconds.

Front 36

How long does it take RF to travel one radar mile?

Back 36

6.18 microseconds.

Front 37

What is recovery time?

Back 37

The time required for the duplexer to complete the transition of switching from the transmitter to the receiver.

Front 38

What is minimum range?

Back 38

The range at which the radar is first able to detect objects.

Front 39

What is the formula for minimum range?

Back 39

(Pulse width+recovery time) times 164 yards.

Front 40

What is the pulse repetition frequency and how is it calculated?

Back 40

1 divided by PRT.

Front 41

Maximum range is determined by what four characteristics?

Back 41

Carrier frequency, peak power of the transmitted pulse, pulse repetition rate/pulse repetition frequency, and receiver sensitivity.

Front 42

What are ambiguous returns?

Back 42

Echoes that exceed the pulse repetition time of a radar. Objects will appear at incorrect ranges.

Front 43

PW x PRF and PW / PRT are the formula for what?

Back 43

Duty Cycle.

Front 44

What is the formula for average power?

Back 44

Ppk x PW x PRF.

Front 45

Does the temperature of the atmosphere increase or decrease uniformly as altitude increases?

Back 45

Decreases uniformly.

Front 46

What is temperature inversion?

Back 46

Temperature will first increase with height and then begin to decrease.

Front 47

What is moisture lapse?

Back 47

The atmosphere over large bodies of water may contain more than a normal amount of moisture. This condition may cause the moisture content to decrease more rapidly at height just above the sea.

Front 48

True or False. Ducting causes the radar horizon to expand or contract; depending on the direction the radar waves are bent.

Back 48

True.

Front 49

How will water or dust particles in the air affect maximum range?

Back 49

They can cause RF energy to be reflected, causing less energy to strike the target.

Front 50

What is the formula for radar horizon?

Back 50

Rnm= 1.25 x antenna height in ft squared.

Front 51

Increasing the antenna height will have what affect on radar horizon?

Back 51

Radar horizon will increase.

Front 52

What does the MDS test identify?

Back 52

Radar sensitivity.

Front 53

True or False. Increasing radar sensitivity will have the same affect on range performance as increasing transmit power.

Back 53

True.

Front 54

What is range resolution?

Back 54

The ability to distinguish between two or more targets that are on the same bearing.

Front 55

What is the formula for range resolution?

Back 55

Pulse width x 164 yards.

Front 56

How far apart must two targets be separated by in order to distinguish two closely-grouped objects' range and bearing?

Back 56

Must be separated by at least one beam width.

Front 57

What is target resolution?

Back 57

The radar's ability to distinguish between closely grouped targets.

Front 58

What is bearing resolution?

Back 58

The ability of a system to distinguish between targets at the same range but different bearings.

Front 59

What is the ideal pulse shape?

Back 59

Square wave with a flat top and sharp leading and trailing edges.

Front 60

True or False. RF radiation hazards exist in the vicinity of radar transmitting antennas; this includes, not only in the front of the antenna, but the sides and rear as well.

Back 60

True.

Front 61

What must you do prior to making any visual inspections of open waveguides, feed horns, and/or any other opening that emits RF radiation?

Back 61

Tag out the equipment.

Front 62

True or False. High-power RF can cause sparks or induce current in other electronic equipment.

Back 62

True.

Front 63

What is the Doppler Effect?

Back 63

Change in frequency of a wave reflected from a moving object.

Front 64

What happens to the frequency of radiant energy reflected from a moving object as it moves further away from the observer?

Back 64

The frequency decreases.

Front 65

True or False. The amount of Doppler Effect is determined by the radial velocity of the object.

Back 65

True.

Front 66

What is radial velocity?

Back 66

Speed the object is moving toward or away from the radar.

Front 67

True or False. The Doppler Effect can be used to determine the velocity of stationary objects.

Back 67

False, The Doppler Effect can be used to determine the velocity of moving objects.

Front 68

True or False. If a target were moving, but remained a set distance from an antenna, it would not produce a frequency shift, because there would be no change in the distance between the target and the antenna; therefore, there would be no change in frequency.

Back 68

True.

Front 69

The continuous wave radar is commonly referred to as the what?

Back 69

Doppler radar.

Front 70

What is the best means to detect moving objects if range resolution is not required?

Back 70

Continuous wave radar.

Front 71

True or False. Doppler radar systems have a duplexer.

Back 71

False.

Front 72

True or False. Pulse Doppler is used in radar applications where ranger determination is critical.

Back 72

True.

Front 73

True or False. In order for Pulse Doppler radar to use the Doppler Effect, the radar must be able to compare the echo signal with a reference signal that is in phase with the transmitted signal.

Back 73

True.

Front 74

What are the three advantages of Pulse Doppler over Continuous Wave?

Back 74

Rejects stationary objects, easily detects moving objects, and distinguishes between targets with same radial velocity but different angles.

Front 75

What are four disadvantages of Pulse Doppler radar?

Back 75

Blind target ranges, blind velocities, range and velocity ambiguities, and reduction in maximum range capabilities.

Front 76

What is NAVEDTRA 14191, Mod 19?

Back 76

The Technician's Handbook.

Front 77

What is step 1 of the 6 step troubleshooting method?

Back 77

Symptom recognition.

Front 78

What is step 2 of the 6 step troubleshooting method?

Back 78

Symptom elaboration.

Front 79

What is step 3 of the 6 step troubleshooting method?

Back 79

Listing probable faulty functions.

Front 80

What is step 4 of the 6 step troubleshooting method?

Back 80

Localizing the faulty function.

Front 81

What is step 5 of the 6 step troubleshooting method?

Back 81

Localizing trouble to the circuit.

Front 82

What is step 6 of the 6 step troubleshooting method?

Back 82

Failure analysis.

Front 83

Define azimuth.

Back 83

Direction to a detected object or target measured in degrees.

Front 84

Define altitude.

Back 84

Height of the detected object or target in feet.

Front 85

Define range.

Back 85

Distance the detected object is from the antenna along the line-of-sight measured in nautical miles.