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([lemma=radar] | [□] □) □
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I discussed with a number of visitors my ideas for using a geometrical optics expansion to recover the surface electrical properties of a material from the first reflection of a radar pulse . If we send out a radar pulse at time ts , which is reflected at the event E , and the echo arrives back at time tr , then we know that the light was traveling at c for the entire round-trip journey out to E and back , so the distance of E is D ( E ) = c * ( tr-ts ) / 2 . Because the scatterometer is a radar instrument , it operates 24 hours a day , collecting data day or night , regardless of sunlight or weather conditions . We present an extended observation of the ionospheric convection in the Northern hemisphere , made by means of the SuperDARN radar network , for a 3 hour period during December 3 , 2001 . To add a historical perspective , almost 40 years ago , when the first national radar network was implemented , a month-long training course was set up at the University of Miami , but only a relatively small group of meteorologists attended . We assume that the radar provides as input the time difference between transmission and return of the radar pulse , as well as the angle of the radar antenna at the time the return pulse is detected . Building on more than 10 years of research and development , Sandia engineers have created a radar tag sensor that can be mounted on military vehicles and is recognizable to an attack aircraft as a " friendly .