Active Sensor & Passive Sensor in remote sensing

Active Sensor & Passive Sensor in remote sensing

1. REMOTE SENSING SENSORS Anurag Ghosh UID NO-2103542 P.R.M.S. Mahavidyalaya Bankura University

2. Introduction of Remote Sensing Remote sensing is the examination or the gathering of information about a place from a distance. This is done by sensing and recording reflected or emitted energy and processing, analyzing and applying that information. Also such examination can occur with device based on the ground or camera based on satellite.

3. What is Sensors? “A sensor is a device comprising of optical component or system and a detector with electronic circuit that will be used to record the reflected and emitted energy from various objected”. Remote Sensing Sensors two type- Active Sensors. Passive Sensors.

4. Active Sensors Active Remote Sensors create there own electromagnetic energy that is transmitted from the sensors towards the terrain, interacts with the terrain producing a backscatter of energy and is recorded by the remote sensors receiver .

5. Active Sensors examples RADARSAT – 1; is the advance Earth observation satellite project developed by Canadian Space Agency (CSA) on 4 th Nov 1995 to monitor environmental change and support resource sustainability. RADARSAT satellite image of Antarctica

6. Passive Sensors Passive Remote Sensing Sensors detect natural energy 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.

7. Passive Sensors examples LANDSAT-1:it was launched on 23th July 1972, at that time the satellite was known as the Earth Resource Technology Satellite (ERTS). It was the first Earth observing satellite to be launched with the express intent to study and monitor our planet Landmasses. LANDSAT 1 satellite image of Lake-Caldera

8. Active Sensors Passive Sensors Different between Active Sensors & Passive Sensors Active transducers generate electric current or voltage directly in response to environmental stimulation. Active Sensors provides their own energy source for illumination. Active Sensors work on any time day or night. Passive transducers produce a change in some passive electrical, such as capacitance, or inductance, as a result of stimulation. Passive Sensors can only be used to detect energy when the naturally occurring energy is available. Passive Sensors work on only day.

9. Advantage of Active Sensor Better control of noise source through control of injected signal. Because propagating fields are generally measured, active experiments usually provided better depth control over source of anomalous signal. Many different source/receiver configurations can be used allowing for a wide variety of survey designs. This allows survey designers great flexibility in customizing survey for particular problems. Once set up, active experiments are capable of producing vast quantities of data that can be used to interpret subtle details of the earths subsurface.

10. Disad vantage of Active Sensor Because both source and receivers are under the surveyors control, he must supply both. Therefore, field equipment tends to be more complex. Field operation and logistics are generally more complex and time consuming then passive experiments. Many different source/receiver configurations can be used allowing for a wide variety of survey designs. The increase in the number of field options inviably leads to greater survey designs coast and potentially to increased The large quantity of data obtained in many active experiments can become overwhelming to process and interpret.

11. Ad vantage of Passive Sensor Surveyor need only record a naturally occurring field; there fore ,he need supply only a sensor and a data recorder. Field operation are generally verry time officiant. This, passive experiments can be run over wider areas in a more cost-effective manner. One ore two well-established procedures are generally used. Contractors can provide these surveys on short notice with relatively esaily quantifiable results. Interpretation of the limited set of observation can be accomplished with modest computational quickly and efficiently.

12. Disad vantage of Passive Sensor Less control of noise because source of the signal is out of the control of the surveyor. Because passive fields are generally the result of integrating anomalous geologic contribution over wide areas, identification of the source of an anomalous reading can be difficult. one or two well-established field procedures is generally used. This limits the amount of customization that can be done for specific problems. The data sets collected in passive experiments are smaller then those collected in active experiments and usually do not allow for as detailed an interpretation.

13. Application of Act ive Sensor Vegetation:- Radar signals interacts with the vegetation in a very complex ways and penetration level of signal depends on it’s strength and water content of the vegetation. Return radar signal may include of trunks, stems and leaves as well ground surface. This type detail information about the vegetation can only be captured using this type of sensor, SAR data are used all over the world nowadays for vegetation studies. Water Bodies:- Fresh water is important for human civilization and maintaining it is very important. Hydrologist seeks to understand the movement, distribution and quality of water on Earth. Active remote sensing like airborne or spaceborne can be used to measure the water in its various forms.

14. Application of Passive Sensor Landsat mission is the longest running mission till the date, earth is observed with the help of it. Tons of information and documentation about changing earth is collected thanks to LANDSAT mission. This mission has been running since 40 years now. Knowing this, one can understand that remote sensing must be throwing some benefits for entire globe. And definitely, that is true. Following is a list of most common applications of passive remote sensing technology. Agriculture, Disaster, Forest, Energy, Fire, Growth of urban areas, etc.

15. Conclusion Sensors is a device comprising of optical component or system and a detector electronic circuitry used to record. It is a very important component in remote sensing. Active sensors are more advantageous then passive sensors.

16. Thank You!