Fun with RADAR

Say 'radar' and most people think of FAA air traffic controllers following airplanes or NASA engineers tracking rockets. But RA dio D etection A nd R anging can be used for a lot of purposes including some that are simply fun. Especially when you can put a whole radar system on a 5mm x 5mm chip, like ViaSat managed to do. If you stand in a canyon and yell, you'll hear an echo when the sound of your voice bounces off the side of the canyon and back to you. Like timing a thunder clap to judge distance to lightning, if you time the echo of your yell and know the speed of sound (roughly a 1000 feet per second) you can estimate how far away the cliffs are (and how close a thunderstorm is). With radar you essentially do the same thing except you use a radio signal instead of sound, and the signal propagates at almost the speed of light (about 11 inches per nanosecond). Send a radio pulse, listen carefully for an echo, and you can tell how far away something is by measuring