[B212]

OK, I will try.....radar can measure the speed of an object, and direction, the aircraft was flying at a known speed, an object from the explosion, would have an initial velocity of the aircraft and the impacted speed of the explosive device....that info would lead to the mathematics indicating size and energy of the explosion...

[TalonDJ]

Also Doppler shift on the frequency of your radar return can tell you the velocity of something.