TRN history, trends and the unused potential

The term Terrain Referenced Navigation is used to describe a larger family of systems that estimate position by measuring terrain heights and comparing them with a digital elevation map. This is not a new navigation technique. In fact, TRN has been around for some time, with its history dating back to the 1950s. At that time the technological possibilities were rather limited, so forerunner terrain sensing systems were completely analog and/or would require the need of the human factor. With the “digital age” TRN methods started to become practical. The 70s and 80s were the decades which account for most of the development in this field. Different processing techniques settled into shape and TRN found practical application especially within military technology. Later on, the interest in terrain sensing methods started to diminish. Nowadays impressive technology exists. For example: laser sensors can measure terrain elevation with a signal having a milli-radian beamwidth; digital maps of 1m resolution are available. These are not the only enablers that warrant a re-investigation of the current potential of TRN. Among other factors we remind the current capabilities in: digital signal processing, real-time computing power and data-storage. Many of the previous limitations of TRN are no longer applicable and therefore this technique may once again be considered a strong candidate for accurate navigation solutions. This paper provides a look into TRN history and illustrates how a set of important developments in the past provide the basis for the (yet unused) potential of TRN for performance-based navigation.