Exploring a GPS Inspired Acquisition and Tracking Concept for Terrain Referenced Navigation

A typical terrain referenced navigation (TRN) system, based on batch processing methods, first collects a sequence of altitude/ depth samples and then compares them with a digital map of the terrain to determine the platform's position. Similar to code acquisition and tracking in GPS, the TRN system needs to find and track a particular sequence of measurements in a larger dataset. TRN systems are based on a real time comparison between the measured depth profile and the known digital terrain database aboard the vehicle. In order to have a clear match between the measurements and the terrain map, it is required to have a good indication of the velocity and the orientation of the platform. The problems arising when dealing with measured errors in the speed and course parameters show similarities with the problems associated with the tracking of arrival times and Doppler offsets in a GPS receiver. Considering the similitude, this paper investigates whether GPS originated solutions have the potential of being applied for TRN with good results. The proposed concept is introduced and the developed TRN algorithm is described.