GEOG Exam 3 questions and answers
graded A+ updated
When was radar developed? Who was the early radar developer? - correct answer ✔✔Late
1800s early 1900s for military purposes. Christian Hansmeyer.
When was imaging radar developed? - correct answer ✔✔1940s WWII
When was the first civilian imaging radar implemented? - correct answer ✔✔1960s: civilian
airborne imaging radar surveys
What was the first civilian radar satellite? When was it operational? - correct answer ✔✔1978
Seasat
What type of electromagnetic radiation does radar use? - correct answer ✔✔Active microwave
radiation: 1 mm to 1 m (300 GHz to 300 MHz)
Surfaces that appear "rough" in visible portion of the spectrum appear ____________ as seen
by microwaves. - correct answer ✔✔Smooth
Benefits of microwave radiation? - correct answer ✔✔Capable of penetrating the atmosphere
under virtually all conditions (still dependent on wavelength, shorter wavelengths are more
susceptible to weather).
Examples of active and passive microwave remote sensing: - correct answer ✔✔Active: Radar
Passive: Microwave radiometer
,*Advantages of radar vs. optical remote sensing: - correct answer ✔✔- Radar can observe Earth
surface day or night during nearly all-weather conditions
- Radar using microwave EMR provides info on surface roughness, dielectric properties of
material, and moisture content
- Longer wavelengths (? slides say frequencies) of radar can penetrate vegetation, sand, and
snow
- Angle of illumination can be controlled
- Spatial resolution can be independent from distance to object
- Interferometric operations create high accuracy mapping of elevation
*Disadvantages of radar vs. optical remote sensing - correct answer ✔✔- Less intuitive to
interpret radar imagery
- Geometric distortions caused by side looking geometry
- Developed by military and less civilian experience than optical remote sensing
What types of information can be gained from microwave EMR detection using radar? - correct
answer ✔✔- surface roughness
- dielectric properties of material
- moisture content
In radar, spatial resolution is (independent/ dependent) on the distance to the object? - correct
answer ✔✔Independent
What type of operations produce high accuracy mapping of elevation? - correct answer
✔✔Interferometric operations
*What does radar stand for? - correct answer ✔✔Radio Detection and Ranging
, What types of radar are there? - correct answer ✔✔- Plan position indicator (PPI)
- Doppler radar
- Imaging radar
*What is RADAR and how does it work? - correct answer ✔✔Radars are TIMING instruments.
A transmitter produces EM waves in radio or microwave domain, sends it out via transmit
antenna, and picks up the signal using a receive antenna (usually same as transmit antenna) and
receiver + processor to determine properties of the object.
Radio waves from Tx reflect off the object (backscatter) and return to receiver.
What is backscatter? - correct answer ✔✔The fraction of incident energy that is reflected
directly backward toward the sensor.
What two types of images does imaging radar produce? - correct answer ✔✔Amplitude image
Phase image
*What is the range direction?
What is the azimuth direction? - correct answer ✔✔Range direction is in the direction the
antenna looks (direction of energy propagation).
Azimuth direction is typically in the direction of the flight path.
What does each pixel in radar image represent? - correct answer ✔✔A complex quantity of the
energy that is reflected back to the antenna. Magnitude represents intensity of the reflected
signal.
*What is slant range?
graded A+ updated
When was radar developed? Who was the early radar developer? - correct answer ✔✔Late
1800s early 1900s for military purposes. Christian Hansmeyer.
When was imaging radar developed? - correct answer ✔✔1940s WWII
When was the first civilian imaging radar implemented? - correct answer ✔✔1960s: civilian
airborne imaging radar surveys
What was the first civilian radar satellite? When was it operational? - correct answer ✔✔1978
Seasat
What type of electromagnetic radiation does radar use? - correct answer ✔✔Active microwave
radiation: 1 mm to 1 m (300 GHz to 300 MHz)
Surfaces that appear "rough" in visible portion of the spectrum appear ____________ as seen
by microwaves. - correct answer ✔✔Smooth
Benefits of microwave radiation? - correct answer ✔✔Capable of penetrating the atmosphere
under virtually all conditions (still dependent on wavelength, shorter wavelengths are more
susceptible to weather).
Examples of active and passive microwave remote sensing: - correct answer ✔✔Active: Radar
Passive: Microwave radiometer
,*Advantages of radar vs. optical remote sensing: - correct answer ✔✔- Radar can observe Earth
surface day or night during nearly all-weather conditions
- Radar using microwave EMR provides info on surface roughness, dielectric properties of
material, and moisture content
- Longer wavelengths (? slides say frequencies) of radar can penetrate vegetation, sand, and
snow
- Angle of illumination can be controlled
- Spatial resolution can be independent from distance to object
- Interferometric operations create high accuracy mapping of elevation
*Disadvantages of radar vs. optical remote sensing - correct answer ✔✔- Less intuitive to
interpret radar imagery
- Geometric distortions caused by side looking geometry
- Developed by military and less civilian experience than optical remote sensing
What types of information can be gained from microwave EMR detection using radar? - correct
answer ✔✔- surface roughness
- dielectric properties of material
- moisture content
In radar, spatial resolution is (independent/ dependent) on the distance to the object? - correct
answer ✔✔Independent
What type of operations produce high accuracy mapping of elevation? - correct answer
✔✔Interferometric operations
*What does radar stand for? - correct answer ✔✔Radio Detection and Ranging
, What types of radar are there? - correct answer ✔✔- Plan position indicator (PPI)
- Doppler radar
- Imaging radar
*What is RADAR and how does it work? - correct answer ✔✔Radars are TIMING instruments.
A transmitter produces EM waves in radio or microwave domain, sends it out via transmit
antenna, and picks up the signal using a receive antenna (usually same as transmit antenna) and
receiver + processor to determine properties of the object.
Radio waves from Tx reflect off the object (backscatter) and return to receiver.
What is backscatter? - correct answer ✔✔The fraction of incident energy that is reflected
directly backward toward the sensor.
What two types of images does imaging radar produce? - correct answer ✔✔Amplitude image
Phase image
*What is the range direction?
What is the azimuth direction? - correct answer ✔✔Range direction is in the direction the
antenna looks (direction of energy propagation).
Azimuth direction is typically in the direction of the flight path.
What does each pixel in radar image represent? - correct answer ✔✔A complex quantity of the
energy that is reflected back to the antenna. Magnitude represents intensity of the reflected
signal.
*What is slant range?
