A while back I notice the simularity between the Ultrasound/IR sensors we use on robots for object avoidance to the concept of basic RADAR. (This is more like UDAR or IRDAR). Direction and range information are what the controller uses to detect objects (RADARs basically use the same information.)
So instead of building robots for a while I decided to see how good I could make my own IRDAR. Wow! One can adjust trigger point, gain and a bunch of other factors and have a way-cool little system!