The radar water tank level meter emits a very narrow microwave pulse, which travels in the space at the speed of light, encounters the surface of the measured medium, and some of its energy is reflected back and received by the same antenna. The time interval between the transmitted pulse and the received pulse is proportional to the distance from the antenna to the surface of the measured medium. Since the propagation speed of the electromagnetic wave is extremely high, it is difficult to confirm that the time interval between the emission pulse and the reception pulse is small (nanoseconds).