SOund Navigation And Ranging or SONAR is a technique of distance measuring between detector and an object base on sound reflection. The distance can be calculated from propagation time and speed of sound in specific mediums. For military, Sonars are the eyes and ears of ships or submarines in water …

Safe and efficient integration of Unmanned Aircraft Systems (UAS) into Civil Airspace is a key challenge for unleashing their potential for non-military applications  “without reducing existing capacity, decreasing safety, impacting current operators, or placing other airspace users or persons and property on the ground at increased risk” Sense and avoid technology  …