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).
