Initialization is performed The Rover can then move. and also at distinct
from the Reference to the Positions can be recorded points if required.
Rover. at a predefined interval...

7.a) (Explain 2 methods - (5x2= 10)

There are two types of remote sensing instruments—passive and active. Passive instruments detect
natural energy that is reflected or emitted from the observed scene. Passive instruments sense only
radiation emitted by the object being viewed or reflected by the object from a source other than
the instrument.

Passive Sensors

A passive sensor is a microwave instrument designed to receive and to measure natural emissions
produced by constituents of the Earth's surface and its atmosphere. The power measured by passive
sensors is a function of the surface composition, physical temperature, surface roughness, and other
physical characteristics of the Earth.The frequency bands for passive sensor measurements are
determined by fixed physical properties (molecular resonance) of the substance being measured.
These frequencies do not change and information cannot be duplicated in other frequency bands.

Passive sensors are patterned after radio astronomy instruments, which detect emissions having
very low power. They are particularly sensitive to accumulated radiation from a multitude of
emitters on the ground, both from within the frequency band in which measurements are being
made, and from out-of-band. Spaceborne passive sensors provide the ability to obtain allweather,
day and night, global observations of the Earth and its atmosphere. These spaceborne passive
sensors operate in frequency bands allocated to the Earth Exploration-Satellite Service or to the
Space Research Service.

Active Sensors

An active sensor is a radar instrument used for measuring signals transmitted by the sensor that
were reflected, refracted or scattered by the Earth's surface or its atmosphere. Spaceborne active
sensors have a variety of applications related to meteorology and observation of the Earth's surface
and atmosphere. For example, precipitation radars measure the radar echo from rainfall to
determine the rainfall rate over the Earth's surface; and cloud profile radars measure the radar echo
return from clouds to provide a three dimensional profile of cloud reflectivity over the Earth's
surface.