To determine which type of remote sensing system uses its own source of energy, we need to explore the basic concepts of remote sensing. Remote sensing can be broadly classified into two categories: passive and active remote sensing systems.
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Passive Remote Sensing: These systems rely on external sources of energy, usually sunlight, to illuminate the target of interest. The sensors detect the reflected or emitted radiation from the target. Examples include optical sensors used in satellites like Landsat, which capture sunlight reflected from Earth's surface.
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Optical Remote Sensing: This usually refers to systems that detect visible, near-infrared, and short-wave infrared radiation. Optical remote sensing can be passive, as it often depends on sunlight.
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Active Remote Sensing: These systems are equipped with their own source of energy to illuminate the target. They emit radiation towards the target and measure the backscattered signals. Examples of active remote sensing systems include radar and LiDAR. Radars emit microwave frequencies, while LiDAR systems emit laser pulses.
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Thermal Remote Sensing: This is typically a passive system, as it detects the infrared radiation emitted by objects. The Earth's surface and atmosphere emit thermal radiation, which is captured by thermal sensors.
Based on the above classifications, Active Remote Sensing is the type of system that uses its own source of energy.
Conclusion: The correct answer is Active remote sensing, as it utilizes its own source of energy to illuminate targets, unlike passive systems which rely on external energy sources.