RADAR, LIDAR, WAM Flashcards
passive vs active systems
passive: detect radiation that is generated by an external source of energy
active: generate and direct energy toward a target and sometimes detects radiation
ex: lidar systems because they detect reflected light
explain radar
- radio detection and ranging
- object-detection system that uses radio waves to determine range, value, or velocity of objects
- higher frequencies are more accurate, but are affected by clouds
radar: define echo
a reflection of a wave that returns to the emitting points after a delay
radar: define doppler shift
the change in frequency or wavelength of wave for an observer who is moving relative to the wave source
define attenuation
a decrease in property in a beam of particles because the distance allows scattering
- water and air influence attenuation of light and sound
explain sar device
- synthetic aperature radar
- a form of radar that create 3d objects
explain radarsat
- a canadian remote sensing earth observation satellite program
- uses sar device
- produces high quality images despite weather
explain lidar
- light detection and ranging
- remote sensing technology that emits intense beams of light and measures the time it takes for the reflections to be detected by the sensor
lidar: what are the computation of the 3d coordinates of the target objects?
- the time difference
- the angle at which the pulse was fired
- the absolute location of the earth
when is lidar data collected?
at night when the air is clearer - unable to penetrate clouds or haze
what is the sampling rate of a lidar instrument?
greater than 150 kilohertz (150,000 pulses per second)
what does the acronym laser mean?
light amplification stimulated emission of radiation
what are the wavelength colors of sunlight, led, and laser?
sunlgiht: different colors
led: monochromatic and non-coherent
laser: monochromatic and coherent
