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364 Cards in this Set

  • Front
  • Back
Radio waves travel at what speed?
1. Speed of sound
2. Speed of light
3. Speed of the Earth's rotation
4. Speed of the Earth's orbit around the sun
2. Speed of light
Which of the following types of energy
CANNOT be seen, heard, or felt?
1. Radio waves
2. Sound waves
3. Heat waves
4. Light waves
1. Radio waves
If a wave has a velocity of 4,800 feet per
second and a wave-length of 5 feet, what
is the frequency of the wave?
1. 9.6 Hz
2. 96 Hz
3. 960 Hz
4. 9,600 Hz
3. 960 Hz

f = v/wavelength
f = 4800/5 = 960Hz
The reception of an AM-band radio
signal over mountains can be explained
by which of the following principles of
wave propagation?
1. Reflection
2. Refraction
3. Diffraction
4. Doppler effect
3. Diffraction
What wave propagation principle
accounts for the apparent increase in
frequency as a train whistle approaches
and the apparent decrease in frequency as
it moves away?
1. Refraction
2. Reflection
3. Diffraction
4. Doppler effect
4. Doppler effect
Varying which of the following wave
characteristics will cause the length of
sound waves to vary?
1. Phase
2. Quality
3. Amplitude
4. Frequency
4. Frequency
Radio-frequency waves CANNOT be seen for which of the following reasons?
1. Because radio-frequency energy is low powered
2. Because radio-frequency waves are below the sensitivity range of the
human eye
3. Because the human eye detects only magnetic energy
4. Because radio-frequency waves are above the sensitivity range of the
human eye
2. Because radio-frequency waves are
below the sensitivity range of the
human eye
The Doppler effect causes a change in what aspect of rf energy that strikes a moving object?
Frequency
The Doppler variation is directly proportional to what radar contact characteristic?
Velocity
Spectrum analysis is a graphic plot of
1. amplitude versus time
2. time versus frequency
3. amplitude versus frequency
4. amplitude versus power
3. amplitude versus frequency
Time-domain plots are used by
technicians to graphically view which of the following waveform parameters?
1. Amplitude versus time
2. Frequency versus time
3. Frequency versus distance
4. Amplitude versus power
1. Amplitude versus time
Which of the following pieces of test equipment should you use to determine
what signals make up a complex signal?
1. Oscilloscope
2. Sweep oscillator
3. Spectrum analyzer
4. Time-domain reflectometer
3. Spectrum analyzer
The action of impressing intelligence upon a transmission medium is referred
to as
1. modulating
2. demodulating
3. heterodyning
4. wave generating
1. modulating
The action of impressing intelligence upon a transmission medium is referred
to as
1. modulating
2. demodulating
3. heterodyning
4. wave generating
1. modulating
The degree to which a cycle has been completed at any given instant is referred
to as the
1. phase
2. period
3. frequency
4. amplitude
1. phase
Which of the following mathematical relationships do you use to figure the period of a sine wave?
1. 1/phase
2. 1/duration
3. 1/frequency
4. 1/amplitude
3. 1/frequency
Which of the following waveform characteristics determines the wavelength
of a sine wave?
1. Phase
2. Period
3. Amplitude
4. Phase Angle
2. Period
2. B
The time during which the pulse is occurring is called PULSE DURATION (pd) or PULSE WIDTH
(pw)
Select the figure letter that corresponds with the pulse width.
1. A
2. B
3. C
4. D
4. E
Select the figure letter that corresponds with the rest time.
1. B
2. C
3. D
4. E
What is the term for the number of complete cycles of ac produced in one second?
1. Period
2. Waveform
3. Frequency
4. Wavelength
3. Frequency
What is the unit of measurement for frequency?
1. Cycle
2. Hertz
3. Period
4. Maxwell
2. Hertz
The value of current of an ac waveform taken at any particular moment of time
is what type of value?
1. Average value
2. Effective value
3. Instantaneous value
4. Peak-to-peak value
3. Instantaneous value
The principal disadvantage of the rhombic antenna is its
1. poor directivity
2. large antenna site
3. low antenna voltage
4. high-frequency inefficiency
2. large antenna site
The unidirectional radiation pattern of the rhombic antenna is caused by which
of the following antenna characteristics?
1. Size
2. Shape
3. Termination resistance
4. Frequency of the input energy
3. Termination resistance
The tendency of EM energy to bend as it passes from a medium of one density to a medium of another
1. Attenuation
2. Reflection
3. Refraction
4. Diffraction
3. Refraction
When EM energy interacts with objects, part of the energy i absorbed by the object and converted into heat.
1. Attenuation
2. Absorption
3. Ducting
4. Diffraction
2. Absorption
The tendency of EM energy to bend around objects in the path of propagation.
1. Attenuation
2. Reflection
3. Refraction
4. Diffraction
4. Diffraction
The natural weakening of a signal as it travels away from the source.
1. Attenuation
2. Reflection
3. Refraction
4. Diffraction
1. Attenuation
The term used for a combination of reflection, absorption, refraction, and diffraction.
1. Attenuation
2. Scatter
3. Ducting
4. Propagation
2. Scatter
EM energy interacts with an object and energy changes direction at an angle that is equal and opposite the angle at which the energy struck object.
1. Attenuation
2. Reflection
3. Refraction
4. Diffraction
2. Reflection
Phenomenon that occurs when energy gets trapped between two atmospheric layers. Atmospheric equivelant to a waveguide.
1. Attenuation
2. Scatter
3. Ducting
4. Propagation
3. Ducting
Highest angle at which a signal, above critical frequency, can be transmitted and still return to Earth.
1. Primary Angle
2. Skip Zone
3. Skip Distance
4. Critical Angle
4. Critical Angle
Measurement along the surface of the Earth from the transmitting antenna to the point where the skywave 1st returns to the Earth.
1. Primary Angle
2. Skip Zone
3. Skip Distance
4. Critical Angle
3. Skip Distance
Special signal used to transmit energy over the horizon.
1. Direct Wave
2. Surface Wave
3. Skywave
4. Over The Horizon Wave
3. Skywave
RF wave that travels straight away from the antenna.
1. Direct Wave
2. Surface Wave
3. Skywave
4. Over The Horizon Wave
1. Direct Wave
RF wave that will strike the ground and be relected by up.
1. Groundwave
2. Ground-Reflected Wave
3. Ground-Refracted Wave
4. Reflected Wave
2. Ground-Reflected Wave
RF wave that strikes the ground and is absorbed.
1. Attenuation Wave
2. Absorbed Wave
3. Surface Wave
4. Ground Wave
3. Surface Wave
Area along the Earth's surface where the signal cannot be received.
1. Primary Angle
2. Skip Zone
3. Skip Distance
4. Critical Angle
2. Skip Zone
Highest frequency that can be transmitted straight up and still return to Earth.
1. Primary Frequency
2. Critical Frequency
3. Skip Distance
4. Critical Angle
2. Critical Frequency
Electrically charged particles that affect
the propagation of radio waves are found
in what atmospheric layer?
1. Troposphere
2. Ionosphere
3. Chronosphere
4. Stratosphere
2. Ionosphere
Most weather phenomena take place in which of the following region of the
atmosphere?
1. Troposphere
2. Ionosphere
3. Chronosphere
4. Stratosphere
1. Troposphere
Radio wave propagation has the least effect because of its constancy on which
of the following atmospheric layers?
1. Troposphere
2. Ionosphere
3. Chronosphere
4. Stratosphere
4. Stratosphere
What two layers in the ionosphere recombine and largely disappear at night?
1. D and F
2. D and E
3. E and F2
4. F1 and F2
4. F1 and F2
Which antenna field always runs parallel to the physical antenna and determines polarization?
1. A-Field
2. E-Field
3. H-Field
4. P-Field
2. E-Field
When the E-Field runs parallel to the the horizon, what is the polarization of the wave?
1. Horizontally
2. Vertically
3. Parallel
4. Positive
1. Horizontally
For best reception, how should the receiving antenna be oriented?
1. Opposite xmitting antenna
2. Vertically
3. Horizontally
4. Same as xmitting antenna
4. Same as xmitting antenna
Higher frequencies require _____ antennas; Lower frequencies require _______ antennas.
1. Shorter; Thicker
2. Shorter; Longer
3. Longer; Shorter
4. Longer; Slimmer
2. Shorter; Longer
An antenna will work equally well transmitting and receiving.
1. Directivity
2. Bi-directional
3. Reciprocity
4. Unilateral
3. Reciprocity
The ability of an antenna to transmit and receive more effectively in one direction.
1. Unilateral
2. Directivity
3. Reciprocity
4. Homogenious
2. Directivity
This antenna is most often used to communicate with subs due to the fact the Low Frequency (LF) signals are able to propagate through ice and water.
1. Long Wire Antenna
2. VEE Antenna
3. Rhombic Antenna
4. Log Periodic
1. Long Wire Antenna
This antenna has only one driven element. It restricts the number of frequencies.
1. Uni-Uda
2. Uni-directional
3. Log Periodic
4. Yagi-Uda
4. Yagi-Uda
This antenna has multiple driven elements with each cut to a different length for use with different wavelengths.
1. Multi-Uda
2. Multi-directional
3. Log Periodic
4. Yagi-Uda
3. Log Periodic
When the E-Field runs perpendicular to the the horizon, what is the polarization of the wave?
1. Horizontally
2. Vertically
3. Perpendicular
4. Positive
2. Vertically
Which frequency designation system is mainly used in the civilian community?
1. Joint Chiefs of Staff (JCS)
2. Intl. Telecom. Union (ITU)
3. Radar Bands
4. FCC
3. Radar Bands
Which frequency designation system was designed to facilitate operational control of electronic combat?
1. Joint Chiefs of Staff (JCS)
2. Intl. Telecom. Union (ITU)
3. Radar Bands
4. FCC
1. Joint Chiefs of Staff (JCS)
What are the primary differences between the ITU and JCS? (one/all that apply)
1. ITU has sub-bands
2. JCS has sub-bands
3. ITU contains wavelengths
4. JCS contains wavelenths
5. JCS more organized than ITU
6. ITU more organized than JCS
2. JCS has sub-bands
4. JCS contains wavelenths
5. JCS more organized than ITU
Which is the only frequency designation system with international standing?
1. Joint Chiefs of Staff (JCS)
2. Intl. Telecom. Union (ITU)
3. Radar Bands
4. FCC
2. Intl. Telecom. Union (ITU)
Which process allows us to move a low frequency up along the spectrum to make transmission easier, and then move it back to its original position on the spectrum for use at the receiver station?
1. Harmonic
2. Nonlinear mixing heterodyning)
3. Linear mixing (heterodyning)
4. Direct Sequence
2. Nonlinear mixing heterodyning)
What is the point-by-point addition of the instantaneous amplitudes of two or more waves?
1. Harmonic
2. Nonlinear mixing heterodyning)
3. Linear mixing (heterodyning)
4. Direct Sequence
3. Linear mixing
What is another term for nonlinear mixing?
1. Heterodyning
2. Homogenizing
3. Direct Sequencing
4. Non-linear combining
1. Heterodyning
What is the fourth harmonic of a 8 Hz sine wave?
1. 16 Hz
2. 24 Hz
3. 32 Hz
4. 40 Hz
3. 32 Hz
What is the speed at which EM energy travels? (one/all)
1. Speed of light
2. 3x10(8)meters per second
3. 3x10(8)feet per second
4. 3x10(6)meters per second
5. 3x10(6)feet per second
1. Speed of light
2. 3x10(8)meters per second
Which frequency designation system lists the frequency bands out of order?
1. Joint Chiefs of Staff (JCS)
2. Intl. Telecom. Union (ITU)
3. Radar Bands
4. FCC
3. Radar Bands
Which wave mixing process resultants contain the original waves and frequencies equal to the sum and difference of the two original waves?
1. Harmonic
2. Nonlinear mixing heterodyning)
3. Linear mixing (heterodyning)
4. Direct Sequence
2. Nonlinear mixing heterodyning)
During which wave mixing process do the original frequencies remain unchanged?
1. Harmonic
2. Nonlinear mixing heterodyning)
3. Linear mixing (heterodyning)
4. Direct Sequence
3. Linear mixing (heterodyning)
What Greek symbol signifies wavelength?
1. Alpha
2. Beta
3. Gamma
4. Lambda
4. Lambda
What’s the term to describe the distance occupied by one cycle of a wave in free space?
1. Wave Duration
2. Wave Period
3. Wavelength
4. Pulse Duration
3. Wavelength
What is the term we use to define a specific location on a wave and to compare two waves to each other?
1. Period
2. Phase
3. 3db
4. Decay Time
2. Phase
What is the relationship between wave frequency and wave period?
1. Proportionate
2. Direct
3. Inverse
3. Inverse
What is the term for the number of cycles a signal completes in 1 second?
1. Frequency
2. Wavelength
3. Duration
4. Pulsewidth
1. Frequency
What is the term for the amount of time needed for a wave to complete one cycle?
1. Frequency
2. Duration
3. Wavelength
4. Period
4. Period
What is the term for amplitude of a wave at any selected point on the wave?
1. Peak Amplitude
2. Average Amplitude
3. Instantanous Amplitude
4. Phase
3. Instantanous Amplitude
What is the term for the maximum displacement above or below the reference line of a wave?
1. Peak Amplitude
2. Average Amplitude
3. Instantanous Amplitude
4. Phase
1. Peak Amplitude
How do we measure amplitude?
1. Hertz
2. Volts
3. Lambda
4. Seconds
2. Volts
What is a single occurrence or iteration of a regularly recurring event?
1. Cycle
2. Pulse
3. Wavelength
4. Frequency
1. Cycle
What do we call waves that are often referred to as noise, static, and transient signals?
1. Sine Wave
2. Periodic Wave
3. Aperiodic Wave
4. Dysfunctional Wave
3. Aperiodic Wave
What is the value of displacement of a wave above or below a reference line?
1. Base Voltage
2. Peak Voltage
3. Amplitude
4. Phase
3. Amplitude
What is the simplest form of a periodic wave?
1. Cycle
2. Sine Wave
3. Linear Wave
4. Non-linear Wave
2. Sine Wave
This antenna has a 360 degree radiation pattern and looks like a doughnut when viewed from the top.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
2. Dipole Antenna
This antenna is used for long range air-air or air-ground communication.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
4. Long Wire Antenna
This antenna looks like a square or diamond made of wires.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
3. Rhombic Antenna
This antenna can make the difference between a site functioning as an EW facility and a GCI facility.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
5. Discone Array
This special purpose antenna propagates its signal in an upward and outward pattern.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
5. Discone Array
These highly directive antennas are used to transmit signals in the upper frequency ranges, UHF, SHF, and EHF.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Microwave
7. Yagi-Uda
6. Microwave
What is the purpose of the Reflector array component?
1. Reflect the signal from the driven element
2. Vibrate out of sync with the driven element
3. Deaden the signal from the driven element
4. Vibrate in sync with the driven element
2. Vibrate out of sync with the driven element
3. Deaden the signal from the driven element
This array component is cut to length based on the frequency transmitted.
1. Driven Element
2. Reflector
3. Director
4. Antenna
1. Driven Element
What is the purpose of the Director array component in an array antenna?
1. Reflect the signal from the driven element
2. Vibrate out of sync with the driven element
3. Deaden the signal from the driven element
4. Vibrate in sync with the driven element
4. Vibrate in sync with the driven element
This antenna is the simplest form of antennas.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
2. Dipole Antenna
This antenna is an array of inverted VEE antennas.
1. VEE Antenna
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
5. Discone Array
This antenna uses line of sight.
1. Microwave
2. Dipole Antenna
3. Rhombic Antenna
4. Long Wire Antenna
5. Discone Array
6. Log Periodic
7. Yagi-Uda
1. Microwave
Name the (3) types of wire antennas from least directive to most directive.
Long Wire, VEE, Rhombic
Name the (3) antenna array components.
Driven Element, Reflector, Director
Name the (3) common types of parabolic refectors used for radars.
Full Dish, Truncated, Orange Peel
This parabolic dish is good for target tracking and engagement but a poor choice for search and EW functions.
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
1. Full Dish Parabolic
This parabolic dish has a very wide, very short beam scanned up and down to locate targets in elevation.
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
3. Orange Peel
This parabolic dish has a narrow beam horizontally and vertically providing very good locational data within a limited space.
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
1. Full Dish Parabolic
This parabolic dish has a very thin, very tall beam scanned left to right or 360 degrees to provide accurate azimuth information.
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
2. Truncated Parabolic
This parabolic dish will not provide good elevation as it covers a large range of altitudes.
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
2. Truncated Parabolic
This parabolic dish will not provide azimuth data.
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
4. Phased Array
3. Orange Peel
Which (2) parabolic dishes are normally deployed together at Ground Control Intercept (GCI) sites?
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
4. Phased Array
2. Truncated Parabolic
3. Orange Peel
Which parabolic dish is commonly associated with weapon systems like SAM's and AAA's?
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
1. Full Dish Parabolic
This is a hollow tube that allows a signal to propagate through the air and prevents energy (heat) loss
1. Waveguide
2. Horn Antenna
3. Phased Array
1. Waveguide
Which radar antenna is commonly used to track ICBM's?
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
4. Phased Array
4. Phased Array
This method of directing a signal is called frequency scanning.
1. Slotted Waveguide
2. Horn Antenna
3. Phased Array
4. Scanning Antenna
1. Slotted Waveguide
What determines the position of the slots in a slotted waveguide?
1. Power of transmitter
2. Frequency to be xmitted
3. Horizontal Orientation
4. Vertical Orientation
2. Frequency to be xmitted
This radar antenna uses numerous antennas, each connected to its own transmitter.
1. Full Dish Parabolic
2. Truncated Parabolic
3. Orange Peel
4. Phased Array
4. Phased Array
What device is used to equalize the pressure between the waveguide and the atmosphere?
1. Pressure Equalizer
2. Horn Antenna
3. Directional Antenna
4. Slotted Wavequide
2. Horn Antenna
4. Slotted Wavequide
Name the (3) component waves involved in the modulation process.
Modulating Wave, Carrier Wave, Modulated Waveform
Which wave type will be changed by the modulation process and its purpose is to hold a place along the frequency spectrum?
1. Modulating Wave
2. Carrier Wave
3. Modulated Waveform
2. Carrier Wave
Which wave type will be used to change or modulate the characteristics of another wave?
1. Modulating Wave
2. Carrier Wave
3. Modulated Waveform
1. Modulating Wave
Which wave type is the result of the modulation process and is transmitted?
1. Modulating Wave
2. Carrier Wave
3. Modulated Waveform
3. Modulated Waveform
Which wave type is sometimes called the information wave because it represents the actual data (voice, sound, etc.) to be transmitted?
1. Modulating Wave
2. Carrier Wave
3. Modulated Waveform
1. Modulating Wave
During this process the amplitude of a carrier wave is altered in step with the amplitude of a modulating wave.
1. Frequency Modulation
2. Voltage Modulation
3. Phased Array Modulation
4. Amplitude Modulation
4. Amplitude Modulation
(Amplitude Modulation) - If a modulating wave has a frequency of 5 Hz and a carrier of 100 Hz, what are the new frequencies?
5 Hz above and 5 Hz below the carrier or 95 Hz and 105 Hz
During which modulation process is it desirable to supress a sideband to reduce cost and power consumption?
1. Amplitude Modulation (AM)
2. Frequency Modulation (FM)
3. Both
4. Neither
1. Amplitude Modulation (AM)
What would happen if you suppressed the lower sidebands for AM and FM waves?
AM - Save power and reduce cost; FM - loss of data by eliminating the low amplitudes in the modulating (intelligence) wave.
A _____ is a sudden rise and fall of voltage or current.
Pulse
What is the general term used to describe the magnitude of a pulse?
Pulse Amplitude
What is the term for the major portion of the pulse where the voltage rises rapidly from the min amplitude to the max amplitude?
1. Rise Time
2. Decay Time
3. Trailing Edge
4. Leading Edge
4. Leading Edge
What is the term for the time it takes a pulse to rise from 10 to 90 percent of its maximum amplitude?
1. Rise Time
2. Decay Time
3. Trailing Edge
4. Leading Edge
1. Rise Time
What is the term for the major portion of the pulse where the voltage drops from the maximum amplitude to the minimum amplitude?
1. Rise Time
2. Decay Time
3. Trailing Edge
4. Leading Edge
3. Trailing Edge
What is the term for the time it takes a pulse to drop from 90 to 10 percent of its maximum amplitude?
1. Rise Time
2. Decay Time
3. Trailing Edge
4. Leading Edge
2. Decay Time
What term refers to the physical length of a pulse in free space?
Pulse Width
What is the term for a time measurement that represents the elapsed time from the beginning of a pulse to the next consecutive pulse, or similiar like point-to-point measurement?
Pulse Recurrence Interval (PRI) (Usually digital equip)
What is the term for a measurement of the number of pulses in a 1 second sample of a pulse train?
Pulse Repetition Frequency (PRF) (Usually analog -flyers)
What is the heart of the basic pulsed radar system?
1. Timer
2. Duplexer
3. Antenna
4. Transmitter
5. Receiver
1. Timer
How many signals are sent from the timer and where is/are they sent?
One sent to modulator
One sent to indicator (timing)
Which radar component is equated to a battery?
1. Timer
2. Modulator
3. Transmitter
4. DC Generator
2. Modulator
The way in which a signal is generated in a BASIC pulse radar is known as?
1. Coherent
2. Non-coherent
2. Non-coherent
Which type of radar never turns the oscillator off which leads to greater pulse stability?
1. Coherent
2. Non-coherent
1. Coherent
Which BASIC radar component generates the DC pulse?
1. Pulse Generator
2. Transmitter
3. Modulator
4. Timer
3. Modulator
Which is the most common method of radar transmission?
1. Coherent
2. Non-coherent
2. Non-coherent
What component of the basic pulsed radar determines the pulse duration?
1. Timer
2. Modulator
3. Transmitter
4. DC Generator
2. Modulator
Which pulsed radar component allows for the use of a common antenna for both transmission and reception?
1. Radar Computer
2. Modulator
3. Signal Processor
4. Duplexer
4. Duplexer
What component of a multi-mode radar supplies a highly stable, low power signal to the transmitter?
1. Radar Computer
2. Exciter
3. Signal Processor
4. Duplexer
2. Exciter
What component of a multi-mode radar performs the function of the timer; determining the PD and PDF for each mode of operation?
1. Radar Computer
2. Exciter
3. Signal Processor
4. Duplexer
1. Radar Computer
This is the EM band with a wavelength longer than visible light and shorter than microwave.
Infrared (IR)
At what temperature does IR exist?
1. Zero degrees C
2. Zero degrees F
3. Zero degrees K
4. Absolute Zero
3. Zero degrees K
4. Absolute Zero
What material radiats IR?
Virtually everything in the enviornment
What are the (3) bands of IR?
Near, Intermediate, Far
How is IR generated?
1. Friction between atoms or molecules
2. Vibrations and rotations of the atoms and molecules
2. Vibrations and rotations of the atoms and molecule
(Friction causes heat)
How does temperature affect IR energy?
Rise in temperature shifts toward visible light (heat metal it turns red)
What are (3) possible interactions between IR energy and objects/features?
Reflection, absorption, transmission
Measure of how well an object absorbs incident IR radiation and reradiates it.
Emissivity
Name (3) factors that effect Emissivity.
Material Type, Condition, Wavelength
Which law describes the atmospheric effect on IR path length?
Inverse Square
What is the difference between the IR energy received at 400 feet versus 200 feet?
1. Half as tense
2. Double as tense
3. One-fourth as tense
4. Same tense
3. One-fourth as tense
Which IF signal will travel the farthest?
1. High frequency
2. Low frequency
3. Short wavelength
4. Long wavelength
1. High frequency
3. Short wavelength
Which RF signal will travel the farthest?
1. High frequency
2. Low frequency
3. Short wavelength
4. Long wavelength
2. Low frequency
4. Long wavelength
What effect does atmospheric conditions have on IR sensors?
1. None
2. Reduced Efficiency
3. Increased Efficiency
2. Reduced Efficiency
What is the most common atmospheric window for IR energy and why?
8 to 14um band. This band is relatively immune to atmospheric absorption
Name the (4) specific thermal properties of IR.
Thermal Conductivity
Thermal Inertia
Thermal Capacity
Surface Condition
Which thermal IR property is a measure of the rate at which heat passes through a material?
1. Thermal Conductivity
2. Thermal Inertia
3. Thermal Capacity
4. Surface Condition
1. Thermal Conductivity
(Metals have higher connectivity than rocks)
Which thermal IR property determines how well a material stores heat?
1. Thermal Conductivity
2. Thermal Inertia
3. Thermal Capacity
4. Surface Condition
3. Thermal Capacity
(Water has a very high thermal capacity)
Which thermal IR property is a measure of the response of a material to temperature changes?
1. Thermal Conductivity
2. Thermal Inertia
3. Thermal Capacity
4. Surface Condition
2. Thermal Inertia
(Water does not respond to temperature changes quickly)
Which thermal IR property describes the condition of a target that may alter the IR signature of an object due to the properties of the surface matter?
1. Thermal Conductivity
2. Thermal Inertia
3. Thermal Capacity
4. Surface Condition
4. Surface Condition
(shiny reflects while matty absorbs)
Which IR waveforms are hotter?
1. Short wavelengths
2. Long wavelenghts
3. High frequencies
4. Low frequencies
1. Short wavelengths
3. High frequencies
(Near band)
What is the naming significants of the 3 IR bands (near, intermediate, far)?
How close the frequency is to the visible band
What is the IR term used to describe the time when no temperature difference exist between two materials?
Thermal Crossover
A Germanium-Gold detector at 60 degrees Kelvin will detect 2.5 to 10um. What is this an example of?
Spectral Sensitivity
The term used to describe how farsighted or nearsighted an IR sensor is.
Spatial Resolution
What are the advantages of IR?
1. Active
2. Passive
3. Good Resolution
4. Day/Night Capable
5. All Weather
6. Immune to atmospheric conditions
2. Passive
3. Good Resolution
4. Day/Night Capable
What are the disadvantages of IR?
1. Active
2. Passive
3. Good Resolution
4. Day/Night Capable
5. All Weather
6. Immune to atmospheric conditions
5. All Weather (NOT)
6. Immune to atmospheric conditions (NOT)
What are the (3) components of an IR imaging sensor?
Optical-Mechanical Scanning Mechanism, Detector, Data Processing
What are a couple advantages of IR weapons guidance?
IR homing is passive, Fire and forget
What are a couple advantages of IR weapons guidance?
Not all weather capable, Older missiles are easily defeated
How is IR jamming accomplished?
Transmit a strong signal within the IR spectrum to confuse the IR seeker to cause break-lock and missile self-destruct
What is the simple radar scan in which a fan beam is rotated 360 degrees in a horizontal plane?
Circular Scan
Which radar search scan provides azimuth and range but NOT elevation?
Circular Scan
What are the radar search scans?
Circular, Modified Circular, Bidirectional Sector, Raster
What is the most common use for the circular scan radar?
Early Warning
What is used in EW of a circular scan?
Radar uses low RF, low PRF, large PD
What radar provides initial, long range detection of ingression aircraft and provides approximate target location?
Early Warning (EW)
Why were OTH radars designed?
Increase long range detection beyond LOS. Increase warning against ICBM
What radar combines the functions of search, acquisition, and target tracking into a single emitter?
Target Acquisition (TA) Change operating modes
What radar is used for semi-active missile guidance?
Target Illuminator (TI)
What are the two sub-components of an IFF system?
Interrogator (sends code)
Transponder (installed on aircraft, responds to code)
What affect does transmitted frequency have on equipment size?
The higher the RF the smaller the equipment
For a given antenna, what affect does increasing the frequency have on the signal's beam width?
Proportionate. Increasing the frequency (shorter wavelength) means a narrower beam width than a low frequency
What parameter is used to determine the maximum unambiguous range of a pulsed radar system?
PRI/PRF (If radar receives a return from its first pulse after a second pulse is sent, it will think its the second pulse return)
Which radar parameter is used to determine the minimum range of a radar?
Minimum range is a function of Pulse Duration (PD)
When a radar completes more than one scan per second, what term is used to describe the speed of the scan?
Scan Rate
(cps) or (hz)
What is the minimum range of a CW radar that uses separate antennas to transmit and receive?
No minimum range
When a radar completes one scan in greater than one second, what term is used to describe the speed of the scan?
Scan Period
(cps) or (hz)
Which radar uses a fan beam that is rotated through 360 degrees in the horizontal plane?
Circular Scan
The V-beam radar was designed to provide what additional target data not provided by the basic EW radar?
Elevation
What technique entails transmitting several beams, stacked in elevation, and each being transmitted at a different frequency?
Multi-stacked Beam
(Each at a diffrent frequency)
In which scan is the antenna beam mechanically swept back and forth through the coverage area (normally less than 180 degrees)?
Bidirectional (BiDi) Sector Scan
A _______ scan utilizes two unidirectional sector scans oriented at right angles to each other.
Track While Scan (TWS)
What is the complex scan called in which a conical scan is superimposed on another scan?
Palmer Scan
(anytime 2 or more scans are combined the new scan is considered to be complex)
What type of scan has no set pattern?
Manual or Irregular Scan
Which radar characteristic provides the most evidence of its intended function?
Scan Type
Utilizing a V-Beam radar, how does it determine elevation?
Time difference between the return of the 1st and 2nd beam. Longer means higher.
Which scan is associated with height finding radars?
Elevation scanning
Which BiDi scan moves up/down over the coverage area?
Vertical
Which BiDi scan is tall and thin?
Horizontal
Which search scan is referred to as a frame when complete?
Raster Scan
The beam of this tracking scan traverses in only one direction
Unidirectional Sector Scan
This scan allows the radar to track one target while searching for others
Tracking While Searching (TWS)
What is FRESCAN?
Frequency Scanning
(electronic scan in which the beam position is determined by the RF)
Which scan is used by fighter aircraft to search for targets?
Raster Scan
Which search scan shifts its beam in elevation after each rotation?
Elevation scanning
What type of search scan is elevation scanning?
Modified circular scan
What type of Doppler frequency shift is associated with a receding target?
Lower frequency
Which Doppler system is primarily designed to seperate targets from a background of clutter?
Moving Target Indicator (MTI)
What causes a change in a waveform's frequency due to a relative motion between an observer and the source of the frequency
Doppler Effect
Is mono-pulsed a tracking technique or scan type?
Tracking
What are the two types of electronic scans?
Phased Array Scanning
FRESCAN
Name (3) common types of Doppler radars.
CW Radar
Pulsed Doppler Radar
Moving Target Indicator (MTI)
Does Doppler radar measure speed or velocity?
Velocity
What does the acronym RADAR mean?
Radio Detection and Ranging
A. Leading Edge
B. Trailing Edge
C. Rise Time
D. Decay Time
E. PRI
Name the parts of the pulse
What is the difference between a periodic waveform and an aperiodic?
Periodic is repetitive; aperiodic is noise or static
What is the difference between a cycle and period?
Cycle is the smallest identifiable portion of a wave; period is the time to complete one cycle
Why is phase important?
Used as a rate of measurement, used to compare to waves, used in phase array directing the beam
How is wavelength and period related?
Multiple the period times the speed of light to determine wavelength
Name (3) displays.
1. Time vs. Frequency
2. Time vs. Amplitude
3. Amplitude vs. frequency
What is the other name for non-linear mixing
Heterodyning
How do you determine a harmonic?
Whole multiples of the lowest (fundamental) frequency
What are the similiarities between ITU and radar bands?
HF, VHF, and UHF
Which field determines polarization?
E-Field (electrical)
Describe horizontal and vertical polarization.
Horizontal is when the E-field runs parallel to horizon and Vertical is when the E-field runs perpendicular to the horizon
What is the relationship between the wavelength and antenna?
Shorter antenna = higher frequency (shorter wavelength)
What are the two non-physical characteristics of the antenna?
Recipocity (receives and sends equally)
Directive (focussed)
What is the simplest form of antenna?
Dipole
What ithe most directive wire antenna?
Rhombic
What is the difference between a periodic waveform and an aperiodic?
Periodic is repetitive; aperiodic is noise or static
What is the difference between a cycle and period?
Cycle is the smallest identifiable portion of a wave; period is the time to complete one cycle
Why is phase important?
Used as a rate of measurement, used to compare to waves, used in phase array directing the beam
How is wavelength and period related?
Multiple the period times the speed of light to determine wavelength
Name (3) displays.
1. Time vs. Frequency
2. Time vs. Amplitude
3. Amplitude vs. frequency
What is the other name for non-linear mixing
Heterodyning
How do you determine a harmonic?
Whole multiples of the lowest (fundamental) frequency
What are the similiarities between ITU and radar bands?
HF, VHF, and UHF
Which field determines polarization?
E-Field (electrical)
Describe horizontal and vertical polarization.
Horizontal is parallel to horizon and Vertical is perpendicular to the horizon
What is the relationship between the wavelength and antenna?
Shorter antenna = higher frequency (shorter wavelength)
What are the two non-physical characteristics of the antenna?
Recipocity (receives and sends equally)
Directive (focussed)
What is the simplest form of antenna?
Dipole
What ithe most directive wire antenna?
Rhombic
What are the (3) components of an array antenna?
Driven Element, Reflector, Director
What is the difference btwn the Yagi Uda and the Log Periodic?
Yagi Uda has only 1 driven element and the log periodic has many
What is a discone array used to communicate with?
Aircraft
What could a discone array be used to identify?
GCI (Ground Control Intercept) site
What is the difference btwn the Orange Peel and Truncated radar?
Orange Peel=Elevation/Range
Truncated=Azimuth/Range
What is the purpose of the waveguide?
Reduce Heat
What does a waveguide end in?
Horn antenna
What is the purpose of the horn antenna?
Equilize the pressure difference of waveguide
Why would you use a slotted waveguide?
So that you wouldn't have to mechanically scan the waveguide
What is the most advanced antenna that we have?
Phased Array
What is the atmospheric layer in which we live?
Troposphere
What atmospheric layer has the most effect of EM energy?
Ionsphere
What are the (3) components of a groundwave?
Surface Wave, Direct Wave, Ground Reflected Wave
What are the (2) parts of the skywave?
Skip Distance and Skip Zone
Describe Critical Frequency and Critical Angle.
CF=Highest frequency that can be xmitted straight up and still return to earth.
CA=Highest angle at which a signal above CF can be transmitted and still be returned to earth
What is ducting?
Trapping of EM btwn 2 atmospheric layers (clouds, air density, etc.) Atmospheric equivelant of a waveguide. (often travel far)
What is the atmospheric condition that allows the wave to go around an object?
Diffraction
Which atmospheric condition involves the bending through mediums?
Refraction
Which atmospheric condition even occurs in a vaccumm?
Attenuation
What are the (3) components of modulation?
Modulating Wave, Carrier Wave, Modulated Wave
Which basic form of amplitude can do single side banding?
Amplitude Modulation (AM)
What do the sidebands do in Frequency Modulation (FM)?
Provide the frequency boundaries
What is involved in Frequency Division Multiplexing (FDM)?
Attaching multiple information signals, divided by frequency, to a single carrier wave.
What can you use in Time Domain Modulation that allows you to get the same information more often?
Strapping
What is the process of reducing the priority of a particular input (sampling it less often)?
Sub-Commutation
Which type of pulse modulation has synchronizer pulses to identify the start and sometimes the stop of the pulse group?
Pulse Frequency Modulation (PFM)
Which type of pulse modulation increases and decreases the pulse duration?
Pulse Duration Modulation (PDM)
Which of the (4) pulse modulation types vary amplitude?
Pulse Amplitude Modulation (PAM)
Which of the (4) spread spectrum techniques is used solely for communications?
Direct Sequence
Which of the (4) spread spectrum techniques is used for radar?
Chirp
What is a different name for Chirp?
Linear Frequency Modulation
Describe the hybrid spectrum spreading technique.
Simply combines frequency hopping with either direct sequence for communications or chirp for radar
What is the objective of CHIRP?
Provides resistance to jamming and improves the ability of a radar to distingish 2 targets close in range.
Define pulse rise time.
Time it takes a pulse to go from 10% to 90% of max amp
What do we call the time it takes the pulse to go from 90% to 10% of max amp?
Decay Time
Where is the pulse duration measured?
50% of leading edge to 50% of trailing edge
What is the relationship btwn PRI and PRF?
Inverse
Define Pulse Repetition Frequency (PRF).
Number of pulses that occur in 1 second
What is Pulse Repetition Interval a combination of?
Pulse time and listening (rest) time
Between the Basic and advanced pulse radars, what is different?
Radar Computer, Exciter, and Signal Processor
How does the Exciter work?
Sets the tone for the whole system, it sends out the frequency that everything matches to
What is the difference btwn a coherent and non-coherent radar?
Coherent (advanced) has an oscillator that is continuously on (stable); Non-coherent (basic) has a timer that turns on/off
What function does the Radar Receiver Protection Device perform?
Acts like a surge protector to the receiver
What is the device that can change what is shown on the display PPI's?
Signal Processor
What function does the Duplexer perform?
Acts as a switch to allow the antenna to xmit/rcv
What is the function of the transmitter in the basic and multi-mode radar?
The xmitter is a high pwr oscillator. In a basic pulsed radar (non-cohert), it rcv pulse from modulator, turns on and produces AC pulse. In a multi-mode (cohert)the xmitter is an amplifier only.
When a radar transmits it has a main beam. What additional beams are present?
Side Lobes and Back Lobes
In a basic pulse radar, why is a timer linked to the display?
Measure how long it takes to get the target return to determine range
What is the relationship between RF and bandwidth?
Higher RF = Narrower bandwidth
If you go to a higher frequency you have a higher potential for interference with what?
Water
Lower RF requires more what?
Power
If a lower RF requires more power, how does this impact equipment size?
Larger equipment
Which travels farther, higher RF or lower RF?
Lower RF
What's the difference between the Pulse Duration and Pulse Width?
PD (Measurement in time)
PW (Measurement in width)
What determines the range resolution (2 planes in front/back of each other)?
Pulse Duration
What is the difference between scan rate and scan period?
Scan Period (if scan is greater that 1 second); Scan Rate (if scan is less than 1 second)
Name the (3) modified Circular Radar Scans.
V-Beam, Multistacked, and Elevation Scanning
Which of the (3) modified circular scans is the most precise?
VEE beam
Why use a BiDi radar versus a circular scan?
Better Elevation (use a vertical BiDi)
Why do aircraft use raster scan?
Needs to search a large area with a small beam (smaller equipment)
What is the difference between BiDi and Unidirectional scans?
Unidirectional scans one-way (on) then fly back (off)
What is the difference between lobe switching and lobe on receive only (LOBO)?
Lobe switch only one is on; LOBO has 3 on and one off
How does a conical scan work?
Power comparison (also lobe switching and monopulse)
What does Doppler provide radar?
Velocity
What does Moving Target Indicator (MTI) do for doppler radars?
Removes clutter (non-moving targets)
Name (2) redundant tracking techniques for monopulse.
Power comparision and
Angular comparison
What are the (3) types of special array antennas?
Linear (1d); Planer (2d); Conformal (3d)
What does Frequency Scanning (FRESCAN) use for an antenna?
Slotted Waveguide
What do we use to determine is someone is an enemy?
IFF (identify friend or foe)
Name the (3) types of missile guides.
Command, Semi-Active, Active
What application is involved in semi-active guidance?
Target Illuminator (TI)
Under which umbrella does Electronic Warfare?
Information Warfare
What are the (2) components of electronic attack?
Destructive and Non-Destructive
What are the (3) components of EW?
Electronic Attack (EA)
Electronic Protection (EP)
Electronic Support (ES)
What do you need to be able to jam something?
Be on the same frequency
Name something that affects RCS.
Size of aircraft
Name (3) catagorizes under shape that affect RCS.
Squared, Angled, Rounded
What are the subcatagories under material composition?
Structural and Parasitic
Name an example of a jamming concept useing a parasitic material composition.
Radar absorbing material (RAM) - paint
Define Burn-Through Range
Echo signal is higher than jam signal
If you use barrage noise (BN) jamming, what happens to burn through range?
It Increases
In addition to the victim radars frequency, what else do you need to know to successfully jam?
Victim Radar characteristics
If you use Spot Noise (SN) jamming, what happens to burn through range?
DECREASE
Chief advantage of SN Jammer is that the output pwr is concentrated in a narrow freq spectrum. This greater pwr density translates to a much shorter burn through range.
Which is better, the Swept Spot Noise (SSN) or the Sweep Lock-on Jammer?
Sweep Lock-on Jammer
What do Cover Pulse jammers do?
Send pulse larger in amp that covers smaller pulse; frequency is the same but time is different to distort range
What is the major form of jamming you would use against monopulse radars?
Blinking
What is the difference between transponders and repeaters?
Repeaters STORE pulse information
What is the difference between RGPO and VGPO?
RGPO (Range Gain)
VGPO (Velocity Gain)
What is false target generation?
Produce one or more high amplitude spikes to generate enough false targets it confuses the radar to which one is true
Name (4) examples of Destructive EA.
Antiradiation Missile (ARM)
High Speed AR Missile (HARM)
Directed Energy (laser)
EM Pulse (EMP)
What is terrain bounce?
Last ditch, low level technique that bounces a strong signal off the ground by flying the a/c straight down toward the ground
What is the target tracking scan that angle deception is used against?
sequential lobe comparison (lobe switching) and CONSCAN radars.
What does blinking do when a missile is launched at you using a monopulse radar?
Causes missile to bleed out kinetic energy prior to reaching target
What is Doppler noise jamming?
Generate random spikes in the velocity bins
What is velocity bin masking?
Generate noise in ALL the bins in hopes of the system decreasing gain and hiding in the noise
Name a passive jamming technique (doesn't radiate)
Chaff
What is the Doppler false target technique?
Generate spikes in just a few frequencies to give the system more appealing targets than the real one.
What is a striking difference between IR and RF?
RF-low frequencies travel farther; IF-short frequencies travel farther
Why is IR catagorized into near, intermediate and far bands?
Shows how close it is to the visible light spectrum
What is emissivity?
How well something can absorb and re-radiate energy
What is the law that deals with path length in IR?
Inverse Square Law (2X =Y/4)
What is Weins displacement law?
A rise in temperature results in a shift in the emitted IR energy toward the shorter wavelenghts (visible spectrum). (example: metal turns red when heated)
Name (4) thermal properties of IR.
Thermal Capacity
Thermal Inertia
Thermal Conductivity
Surface Condition
Give an example of thermal crossover
Condition at dawn when water and bridge are the same temp so IR can't distingish
What is the major benefit of IR in a military application?
Passive and fire-and-forget
What is spacial resolution?
IR Can distingish between the objects
When we are talking about good IR contrast, what are we talking about?
Big temperature differences between objects
What is an advantage of MODERN IR missiles?
All aspect intercept(includes plume), flare rejection capability, cooled seeker heads
When a laser beam leaves the optical cavity it is highly _________?
Divergent
What do you need to narrow a laser beam?
Lens
When you use a lens on a laser beam it becomes more _________?
Collimated
What has the ability to disrupt the structural integrity of a missile in flight?
Airborne Laser (ABL)

Megawatt class chemical oxygen iodine laser (COIL) primarily designed to shoot down Tactical ballistic missilies (TBM). (Doesn't burn through)
What is a gain medium (laser)?
Material/type of atom in optical cavity (determines the type of laser)
What is the type of gain medium used in CD players?
Semi-conductor
Which gain medium is most common in dazzlers?
Dye
What are the (3) countermeasures agains dazzlers?
Clear to Opaque Window
Nonlinear Optics (goggles)
Narrow Band Visor Filter
What is a Palmer Scan?
Combination of the Conical scan over others such as the raster - Palmer Raster
Which laser is one of the most basic?
Solid State - Ruby laser
Which type of laser is very efficient as a range-finding laser?
Gas (known for their red light)
Which type of laser is known for its ability to cut metal due to its high power output?
Gas
Which type of laser is used in procedures such as Lasik?
Solid State
What does the acronym LASER stand for?
Light Amplification by Stimulated Emission of Radiation
What is the monopulse radar also called?
Simultaneous lobe comparison
Is the monopulse radar used for scanning or tracking?
Tracking. It is very similiar to the LORO except all four receiver antennas are on at the same time.