In this technique, the Probert–Jones equation sets the backscattered power proportional to the reflectivity factor Z. (-5[1])Before it was used for diathermic heating, the cavity magnetron was developed for use in this technique. (10[2]-5[2])FM is often combined with the “continuous-wave” form of this technique, (-5[4])which predates (-5[1])a variant that measures the phase shift between pulses (10[2]-5[1])to observe features (-5[1])like hook echoes. (10[4]-5[4])The (10[1])velocity (10[3]-5[1])of water (10[3])droplets (10[2])can be measured via the Doppler (-5[1])effect (10[1]-5[1])in this (10[2])technique, (10[3])which is (10[1]-5[1])able to detect (10[2]-5[3])supersonic V-2 (-5[1])rockets. (10[2]-5[2])The NWS (10[5])uses this (10[1])technique (10[5])to (10[2])track (10[2])weather (10[4]-5[1])patterns. (10[18]-5[1])For 10 (10[2])points, (10[5])name this technique (10[1])that uses (10[1])radio waves (10[6]-5[1])to (10[1])find (-5[1])the distance to an object. (10[5]-5[1])■END■ (10[21]0[14])