What is an active sensor?
Active sensors create their own electromagnetic energy that is transmitted from the towards the terrain, interacts with the terrain producing a backscatter pf energy and is recorded the remote sensor's receiver.
What is a passive sensor?
The passive sensor detects the naturally emitted microwave energy within its field of view.
What is a passive sensor?
The passive sensor detects the naturally emitted microwave energy within its field of view.
The main key difference between active and passive sensors are given below.
Active sensor :
- An active sensor is transducer generates electric current or voltage directly in response to environmental stimulation.
- Active sensor both transmit and measure electromagnetic energy.
- Active sensor self destructs during hijack attempts.
- Active sensor actively transmits measurement to ground stations whether the personnel on duty want the data or not.
- The active sensor emits their own EM energy which is transmitted towards the earth and receives energy reflected from the earth. The received EM(electromagnetic) energy is used for measurement purpose.
- It provides their own energy source for illumination.
- Active sensors are able to obtain measurement anytime.
- Example of active sensor like communication satellite, earth observation satellite, LISS -1, etc.
Passive sensor :
- The passive sensor is transducer produces a change in some passive electrical quantity such as capacitance, resistance or inductance as a result of the stimulation. These usually require additional electrical energy for excitation.
- The passive sensor only measures electromagnetic energy.
- The passive sensor has no defence against enemy attack.
- Passive sensors wait patiently until data are requested.
- The passive sensor receives naturally emitted EM energy within its field of view and performs measurement using it.
- Passive sensors can only be used to detect energy when naturally when the naturally occurring energy is available.
- Passive sensors can obtain measurement only in the day time.
- Example of passive sensor like remote sensing satellite, SPOT-1, LANDSAT-1, etc.
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