Types of Remote Sensing

There are two type of remote sensing sensors which is based on the sensors are as follows:

• Passive sensors
• Active sensors

Passive Sensors

Passive sensors detect natural energy(radiation) that is emitted or reflected by the object or scene being observed. Reflected sunlight is the most common source of radiation measured by passive sensors. Sensing done via active sensors is called active sensing. For excitation, they often need extra electrical power. Only when the energy that naturally occurs is available can passive sensors be utilized to detect it, during the day can passive sensors gather data, electromagnetic energy is measured by the passive sensor.

The passive sensor is defenseless against an invading force. Sensors that are passive wait patiently for data requests. As a result of the stimulation, the passive sensor’s transducer causes a change in a passive electrical quantity like capacitance, resistance, or inductance.

The passive sensor measures utilizing EM radiation that is naturally emitted within its field of view. Satellites used for remote sensing, such as SPOT-1 and LANDSAT-1, are examples of passive sensors.

Active Sensors

Active sensors transmit their own signal and measure the energy that is reflected and transmitted back or scatter back from the target. For example, radar sonar. Sensing done via passive sensors is called passive sensing. A transducer that is an active sensor directly produces electric current or voltage in response to external stimulus. The active sensor produces its own electromagnetic (EM) energy, transmits it toward the earth, and then collects energy reflected back from the planet. Electromagnetic (EM) radiation that has been received is used for measurement.

They self-destructs during hijack attempts and can take measurements at any time. Electromagnetic energy is measured and transmitted by active sensors. Regardless of whether the on-duty employees want the data or not, an active sensor actively communicates measurement to ground stations. It provides their own energy source for illumination. Example of active sensor like communication satellite, earth observation satellite, LISS -1, etc.

In this article, we will study remote sensing which has its importance in today’s era and helps in many ways in the monitoring and detection of the area’s physical characteristics with radiation and reflection. Remote – Something which is far away, Sensing – Getting information or getting data; remote sensing is getting or collecting information from far away or without being in contact with the object. The characteristics of an area are monitored with the radiation. It means it is the acquisition of information regarding any object without being in touch with that object- it means acquiring information from a distance, typically from aircraft or satellites.

This technology is used in various fields – geography, geology, hydrology, etc. It gives a large area of coverage to find information regarding the large area and more objects. To understand the weather assessment, large land area use, ocean use, and assessment are provided with this technology.