Today I filed a patent for an application of Sonar that I think is very promising.. Yes Sonar, like the way bats navigate, but different in that my technique does not use echoes. Basically the idea is more like GPS. With GPS, the ID of the satellite and the time stamp from each satellite along with the satellites location above the earth is sent out for people to navigate by. Since all the satellites use the same time reference, the device you are using simply measures the time it takes for each time signal to get to your device at the speed of light and using triangulation principles to know pretty accurately where you are on the earth’s surface. A really good explanation of the principle can be seen at Wikipedia: http://en.wikipedia.org/wiki/Global_Positioning_System#Basic_concept_of_GPS About 14 months ago I started working on the idea of using a similar system but using sound waves instead of line-of-sight radio waves for triangulation in smaller spaces...
Official Web site of Inventor Ric Richardson