The MASS-03 Radio Altimeter Continuous Echo Signal Simulator is a specialized testing device designed to generate stable, continuous echo signals that replicate real-world altitude-related signal environments for radio altimeters. Tailored to support the development, calibration, and performance verification of radio altimeters, it accurately simulates various echo signal characteristics (such as amplitude, frequency, and delay) corresponding to different altitude scenarios, enabling users to test critical functions of radio altimeters—including height measurement accuracy, tracking stability, and anti-interference performance—under controlled laboratory conditions. By providing reliable, repeatable continuous echo signals, the simulator eliminates the need for costly and complex field tests, streamlining the testing process while ensuring radio altimeters meet design specifications for accuracy, stability, and robustness in practical operation.