Remote sensors measure electromagnetic radiation properties from a medium, categorized into passive and active sensors. Passive sensors detect naturally occurring energy, limited by factors like time and latitude, while active sensors emit their own radiation to gather data regardless of environmental conditions. Examples include thermal mappers for passive sensing and synthetic aperture radar for active sensing.

2. Subject:- Remote Sensor…

3. 
Remote Sensors are the device
that measures the properties of
electromagnetic radiation
leaving a medium due to
scattering or emmision…

4. 
There are to types of Remote sensore

1. Passive Sensor

2. Active Sensor

now let’s take a look at there types in
detail….

5. It senses natural radiation which is either
emmited or reflected from the target
 The sun’s energy is either reflected , as it
is visible wavelengths or absorbed and
then re-emitted as it is for thermal
infrared wavelengths.
 Passive sensors only be used to detect
naturally occuring energy.


6. there is no reflected energy available
from sun at night.
 The amount of solar radiation present at
polar latitude is often insufficient for
visible light sensors limiting the use of
passive sensor to lower latitude.


7. 
The problem associated with passive
remote sensing can be overcome by
designing a remote sensing system in
which a sensor can be used that is
capable of detecting radiation in several
different portion of the electromagnetic
spectrum.

8. For example, by using a combination of
visible and thermal infrared channel,
whether satellites can provide imagery
of the earth’s cloud patterns during both
day and night hours.
 Similarly Thermal Mapper is a good
example of the Passive Sensor, this sensor
has seven band or channel


9. The sensors which produces its own
electromagetic radiation of a specific
wavelengths and the interactionof this
radiation with the target is studied for
target identification are called active
sensors.
 It is the direct burst of radiation at the
target and use sensors to measure.


10. 
Most often the sensor detects the
reflection of the energy, measuring the
angle reflection or the amount of it took
for the energy to return.

It provide the capability to obtain
measurements any time, regardless of
the time of the day or season.

11. Synthetic Aperture Radar (SAR) is one of
the best example of an active remote
sensing technology.
 Doppler radar is another example of an
active remote sensing technology.
 A sensor measure the reflection or echos
of this energyoff such atmospheric
particle
