What does the term "radar altimeter" refer to?

The term "radar altimeter" specifically refers to a device that measures altitude above the ground by utilizing radar signals. It operates by sending out radar waves towards the ground and measuring the time it takes for the waves to return after reflecting off the ground. This time delay is then converted into an altitude reading. Radar altimeters are particularly useful in aviation as they provide accurate altitude readings close to the earth's surface, which is critical during landing approaches and for terrain avoidance. Unlike barometric altimeters, which measure altitude based on atmospheric pressure, radar altimeters provide measurements independent of weather conditions and pressure variations, making them essential for precision flying.