Att Et Test 10 Radars

Front 1

Components of a typical communications system

Back 1

Transmitter, receiver, modulator

Front 2

Superimposition of low frequency information on a higher frequency carrier signal

Back 2

Modulation

Front 3

"Intelligence" extracted from the carried

Back 3

Demodulation

Front 4

Conversion of audio frequency to sound frequency accomplished by...

Back 4

Loud speaker

Front 5

Most important region of the earth's atmosphere for long distance, point to point communications

Back 5

Ionosphere

Front 6

F-layer

Back 6

Highest of ionospheric layers, also has longest propagation capability

Front 7

The lower the frequency of a radio wave....

Back 7

The more rapidly the wave is refracted by a given degree of ionization

Front 8

Critical frequency

Back 8

Maximum frequency just below the "escape point"

Front 9

As wavelength decreases and frequency of a radio wave increases, the diffraction ability...

Back 9

Decreases

Front 10

D-layer

Back 10

Disappears at night

Front 11

Skip zone

Back 11

Area of silence between the end of the Ground Wave Coverage and the beginning of the Sky Wave Coverage

Front 12

Critical angle

Back 12

Radio waves depend on the layer density and wavelength of the signal

Front 13

Factors that influence ionospheric refraction

Back 13

Ionospheric density, transmitter operating frequency, and angle at which radio waves strike the ionosphere

Front 14

Critical frequency

Back 14

Each layer of the ionosphere has a maximum frequency that it will refract

Front 15

Purpose of the HF system

Back 15

Provide long range high frequency surface to surface, surface to air, and air to air radio comms

Front 16

What enables the HF system to communicate over long ranges

Back 16

High power transmitter, sensitive receivers, and ionospheric conditions

Front 17

Frequency range for HF systems

Back 17

3MHz to 30MHz

Front 18

Most common mode of HF systems

Back 18

USB

Front 19

Receiver transmitter

Back 19

HF system component that contains all the circuitry required to generate transmission signals and process received RF signals into audio signals

Front 20

Antenna coupler

Back 20

Electrically couples the antenna to the receiver transmitter

Front 21

Phase lock loop circuit

Back 21

Demodulates FM signals according to frequency variations produced by the difference between the FM input frequency and VcO frequency

Front 22

If the VCO frequency is lagging the reference frequency...

Back 22

The DC error voltage increases

Front 23

Phase lock loop

Back 23

Commonly used for band pass filter

Front 24

The PLL would be erratic or not work at all if...

Back 24

The low pass filter is missing

Front 25

Amplitude of DC error voltage

Back 25

Directly proportional to the phase difference between the comparator's input signals

Front 26

When VCOs free running frequency matches the reference signal phase and frequency...

Back 26

DC error voltage is 0VDC

Front 27

When the error voltage from the low pass filter increases...

Back 27

VCO output frequency increases

Front 28

Component of PLL that has a center frequench

Back 28

VCO

Front 29

Component of PLL that has a center frequench

Back 29

VCO

Front 30

PLLs output of the low pass filter

Back 30

Error voltage

Front 31

PLL system make-up

Back 31

Phase detector, frequency counter/divider, VCO and loop filter

Front 32

Two categories of frequency synthesis

Back 32

Direct and indirect

Front 33

Sequential circuits employ

Back 33

Digital gates and components

Front 34

Typical AM receiver includes:

Back 34

RF section, mixer, LO, IF amp, AM detector, AGC and AF amp

Front 35

Frequency at the output of the IF amp should be

Back 35

455 kHz

Front 36

Local oscillator in the AM receiver

Back 36

Tuned to 455kHz above the tuned RF

Front 37

Purpose of AM detector circuit

Back 37

Extracts the intelligence from the IF

Front 38

Purpose of AGC circuitry

Back 38

Eliminate fluctuations in the output when RF input varies

Front 39

Bandwidth of IF filter

Back 39

Approx 10kHz

Front 40

Two basic categories of AGC

Back 40

Carriers derived and audio derived

Front 41

Of the two AGC types

Back 41

Carrier derived is most common

Front 42

Low pass filter following the detector diode

Back 42

Removes remaining IF signal

Front 43

FM side bands that contain the majority of the power

Back 43

Significant side bands

Front 44

Advantages of FM

Back 44

Less interference between stations, greater noise suppression, and reduced transmitter power to cover an assigned area

Front 45

FM receiver's ability to select the stronger of two signals with the same frequency

Back 45

Capture effect

Front 46

Standard FM broadcast IF

Back 46

10.7MHz

Front 47

100 channels spaced 200kHz apart

Back 47

fM broadcast band of 88 to 108 MHz

Front 48

VCO output

Back 48

10.7MHz below the incoming tuned RF

Front 49

Incident traveling waves

Back 49

RF signal traveling through a transmission line

Front 50

Squelch circuit

Back 50

Quiets the transceiver when a signal is not present

Front 51

CH radio limited to...

Back 51

Transmissions at 5W

Front 52

Common SSB used by military

Back 52

ISB

Front 53

Balanced modulators

Back 53

Produce only the sum and difference

Front 54

Demodulation in SSB receivers accomplished by

Back 54

Product detectors and balanced modulators

Front 55

Balanced modulator

Back 55

Suppresses the carrier

Front 56

SSB receivers require that the carrier

Back 56

Be recreated in order for the intelligence to be detected

Front 57

Bandwidth for NBFM

Back 57

10kHz to 30kHz

Front 58

Advantages of NBFM Comms

Back 58

RF spectrum conservation, greater noise suppression and reduced transmitter power to cover assigned area

Front 59

Part of comms troubleshooting phase

Back 59

Repair phase, assessment phase, and reassessment phase

Front 60

RF energy reflected from an object provides

Back 60

Range, bearing, elevation and velocity

Front 61

Video detector

Back 61

Converts IF pulses to video pulses

Front 62

Immediately after transmitter fires..

Back 62

STC circuit reduces the receiver gain to zero

Front 63

FTC

Back 63

No effect on receiver gain

Front 64

Characteristic impedencd

Back 64

Distributed induction and capacitance of the line

Front 65

Skin effect

Back 65

Loss due to high frequency currents flowing near the outer surface of the conductor

Front 66

Two wire transmission line

Back 66

Allows greatest RF velocity (97% of the speed of light)

Front 67

Twisted pair transmission line

Back 67

Allows the least velocity (60% speed of light)

Front 68

In a waveguide as the frequency increases

Back 68

Metallic insulator smaller in size

Front 69

In a waveguide the bus bar increases when

Back 69

The frequency increases

Front 70

Duplexer

Back 70

RF switch that permits radar system to use a single antenna to both transmit and receive

Front 71

Physical handling and installation of waveguides

Back 71

Plumbing

Front 72

Dummy load

Back 72

Resistive load that absorbs all the energy from the transmitter so it doesn't leave the antenna

Front 73

Balanced hybrid crystal (magic-t) found at the input of the radar receiver

Back 73

Used as a mixer

Front 74

Couples the maximum strength of the E-field

Back 74

Locate a probe in the center of the "a" wall, 1/4 wavelength from the shorted end of the waveguide

Front 75

Efficiency

Back 75

Ability of an antenna to couple or radiate energy into space

Front 76

Directivity

Back 76

Ability of an antenna to direct most of its power in a concentrated area

Front 77

An antenna's power gain is measured in relation to

Back 77

Reference antenna

Front 78

Height finding radar

Back 78

Antenna has a narrow vertical beam width

Front 79

Adding a reflector to a horn antenna

Back 79

Increases power gain and Directivity

Front 80

Advantages of cavity resonator

Back 80

High Q, high power, small size and ruggedness

Front 81

If the CW RADAR RF energy reflects off an inbound object

Back 81

Frequency increases

Front 82

Typical RC circuit cannot be used in microwave frequencies because

Back 82

Components cannot be manufactured with small enough values

Front 83

Causes oscillations

Back 83

At high frequencies, the Cpg value of the interelectrode capacitance

Front 84

At high frequencies, the Lg value of lead inductance can cause

Back 84

Attenuation of the input signal

Front 85

Electron transit tims

Back 85

Time it takes for electron to travel from cathode to the plate

Front 86

Resonant cavities of a magnetron begin oscillating as a result of

Back 86

Electrons passing by the opening to the cavity resonators

Front 87

Bipolar and FET

Back 87

Used for amplifiers/oscillators in microwave circuits

Front 88

Gallium Arsenide is used in FETs to reduce transit time by reducing

Back 88

Ion mobility

Front 89

Principle of Varactor operation

Back 89

PN junction capacitance

Front 90

Tunnel diode operation

Back 90

Involves electrons flowing across PN junction before the barrier voltage is reached

Front 91

Gunn diode operation

Back 91

Transfer of electrons

Front 92

Purpose of AFC circuit

Back 92

Compensate for drift and age of components

Front 93

Dro operation

Back 93

Involves the dielectric resonator

Front 94

Semiconductors that exhibit negative resistance

Back 94

Gunn and tunnel diodes

Front 95

Dry air in a waveguide

Back 95

Prevents arcing

Front 96

Element in telltale oil filter should be changed

Back 96

Just before red element indicator reaches red line

Front 97

Type 1 dehydrator

Back 97

Uses refrigerant to remove liquid and oil

Front 98

Purpose of dust filter in dry air system

Back 98

Prevents desiccant and dust from contaminating dry air system

Front 99

Dew point in a waveguide should be kept below

Back 99

-40 degrees F

Front 100

Dehydrator of dry air system

Back 100

Contains two desiccant chambers

Front 101

Hermetically sealed

Back 101

Prevents entrance of moisture

Front 102

Primary system

Back 102

Provides initial source of cooling water that can be either seawater or chilled water

Front 103

Scan indicator

Back 103

Common in a weapons control RADAR

Front 104

Secondary system

Back 104

Transfer heat load from electronic equipment

Front 105

Cylindrical parabolic antennas

Back 105

3D air search and ground control precision

Front 106

Radar uses one antenna to both transmit and receive RF energy

Back 106

Duplexer

Front 107

Function of the PFN in Line-type modulator

Back 107

Stores energy to create High Voltage pulse

Front 108

PFN discharge time determines

Back 108

Pulse width of radar. It controls the time the transmitter tube generates an RF energy output

Front 109

Intermediate Frequencies normally used in RADAR receivers

Back 109

30MHz to 60MHz

Front 110

What type of transmission line uses the outer conductor to shield the center conductor

Back 110

Flexible coaxial cable

Front 111

The strength of the H-field is indicated by the number of H-lines in a given area and varies directly with the amount of

Back 111

Current

Front 112

What characteristic of a vacuum tube can attenuate an input signal at high frequencies?

Back 112

Lead inductance

Front 113

What characteristic of a vacuum tube can attenuate an input signal at high frequencies?

Back 113

Lead inductance

Front 114

What characteristic of vacuum tubes can attenuate an output signal at high frequencies?

Back 114

Interelectrode capacitance

Front 115

What characteristic of a vacuum tube can attenuate an input signal at high frequencies?

Back 115

Lead inductance

Front 116

What characteristic of vacuum tubes can attenuate an output signal at high frequencies?

Back 116

Interelectrode capacitance

Front 117

Klystron

Back 117

Overcomes the problems of conventional tubes. Uses a bunched cavity and grid to modulate the electron flow. Produces amplified oscillations.

Front 118

Magnetron

Back 118

Overcomes the problems of conventional tubes at microwave freqs. Uses resonant cavities to produce oscillations.