Remote Sensing refers to the acquisition of information about an object without touching it. In modern usage, Remote Sensing makes use of aerial sensor technology to detect and classify objects. The aerial sensors detect objects both on the surface of the earth and in the atmosphere by means of propagating signals. These signals are electromagnetic radiations that are emitted by aircraft and satellites.
Active Remote Sensing is a class of remote Sensing that makes use of Active Remote Sensors. These sensors provide their own source of illumination and they emit radiations that are directed towards the target body that is to be investigated. Active Remote sensors emit energy in order to scan the objects and areas and they then detect and measure the radiations that are reflected or are backscattered from the target body.
The sensors transmit short pulses of the electromagnetic energy in the direction of the target and they record the origin and strength of the reflected rays received from the object within the system's field of view.
An active Remote Sensing System is not dependent on the sun's rays or the thermal properties of the earth. However the system requires a fairly large amount of energy to illuminate the target body. The sensors that are used in this system create their own electromagnetic energy that
The sensors transmit short pulses of the electromagnetic energy in the direction of the target and they record the origin and strength of the reflected rays received from the object within the system's field of view.
An active Remote Sensing System is not dependent on the sun's rays or the thermal properties of the earth. However the system requires a fairly large amount of energy to illuminate the target body. The sensors that are used in this system create their own electromagnetic energy that
- Is transmitted from the sensor towards the contour
- Interacts with the contour and produces reflected rays
- Is recorded in the remote sensor's receiver
The advantages of Active Remote Sensing are :
- Ability to take measurements regardless of the time of the day or the season.
- Easy to examine the wavelength of the radiations that are not provided by the sun.
Active remote sensors can be used to observe the earth's surface even when the sky is covered with clouds. This is because they rely on their own source of radiation to illuminate the object. This is done so that the energy radiated and reflected to the sensors is measured.
The most common type of sensor that are used for Active Remote Sensing is a “RADAR”. Another example of an active remote sensor is LiDAR. They measure the time delay between the emission and return to establish the location, direction and speed of the object.
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