Radio Detection And Ranging (RADAR) / Light Detection And Ranging (LIDAR) Practice Exam

In the context of RADAR and LIDAR, "echo" specifically refers to the reflected signal that returns to the sensor after it has bounced off an object. This concept is fundamental to how these technologies work. When a RADAR or LIDAR system sends out a pulse of electromagnetic waves, those waves travel through the environment and encounter various objects. Upon hitting an object, the waves are reflected back towards the source, creating what is known as an echo.

The system then detects this returning signal, which allows it to calculate the distance to the object, determine its size, and in some cases, its speed. This process of sending out pulses and receiving the returning echoes is what enables RADAR and LIDAR to create images or gain information about the surrounding environment.

The other choices do not accurately describe the concept of echo in this context. The sound made by birds is unrelated to the principles behind RADAR and LIDAR. The original signal sent out is known as the transmitted signal, not the echo. A type of interference pattern pertains to different concepts of wave behavior and does not directly relate to the defined function of an echo in these systems.