Design Evolution of AMSADD
AMSADD was originally conceived in 1974 using VOR / DME as the primary input for positioning information. Today, with GPS, the positioning is exact. AMSADD has evolved over time with pilot and engineer input from various presentations given to pilot groups, ALPA, PATCO (now inactive), the FAA, and various avionic engineering firms across America.
As each presentation was made, comments such as, "why don't you make it do this" or, "why don't you make it do that" was common. We did make it "do that" and "do this" as time went on. While the original design was solid in its concept, the fine tuning or "tweaking" came from pilots and engineers who believed in AMSADD.
Today AMSADD has become a "polished diamond" from the original "diamond in the rough." While it may sound arrogant for us to make this claim, we believe that AMSADD is the the finest terrain awareness design anywhere. 
We have faith that AMSADD will become the primary method of terrain awareness in the near future. After all, the cat scan and the ultra sound were both invented over twenty years before they became renowned. Great inventions take time for people to see their importance because of the advanced thinking that went into the conception of the idea.

History of Ground Proximity Warning Displays System Comparisons
Psychology of Colors Flight Tests