Remote sensing Sensor
INTRODUCTION: Sensors: Sensors can be classified as passive or active. Sensors, which sense natural radiations, either emitted or reflected from the Earth, are called passive sensors. It is also possible to produce electromagnetic radiation of a specific wavelength or band of wavelengths and illuminate a terrain on the Earth’s surface. The interaction of this radiation with the target could then be studied by sensing the scattered radiation from the targets. Such sensors, which produce their own electromagnetic radiation, are called active sensors. A photographic camera, which uses only sunlight, is a passive sensor; whereas the one, which uses a flashbulb, is an active sensor. Again, sensors (active or passive) could be either imaging, like the camera, or non-imaging, like the non scanning radiometer. Sensors are also classified on the basis of range of electromagnetic region in which they operate such as optical or microwave. The majo...