A New Independent GPS-Free System for Geo-Referencing from Space

Abstract

A new system's geo-referencing from space is entirely free from any GNSS (GPS or equivalent) systems. The system addresses to various strategic and economic applications such as in remote clock synchronism, aircraft and balloon navigation, missile and smart bombs tracking, satellite orbital determination and remote target geo-positioning. The new geometry concept corresponds to an "inverted GPS" configuration, utilizing four ground-based reference stations, synchronized in time, installed at well known geodesic coordinates and a repeater in space, carried by an aircraft, balloon, satellite, etc. Signal transmitted by one of the reference bases is retransmitted by the transponder, received back by the four bases, producing four ranging measurements which are corrected for the time delays undergone in every retransmission. A minimization function was derived to compare the repeater's positions referred to at least two groups of three reference bases, to correct for the signal transit time at the repeater and propagation delays, and consequently to provide the accurate repeater position for each time interaction. Once the repeater's coordinates are known, the other determinations and applications become straightforward. The system solving algorithm and process performance has been demonstrated by simulations adopting a practical example with the transponder carried by an aircraft moving over bases and a target on the ground. Effects produced by reference clock synchronism uncertainties at the four bases on the measurements are reviewed.

Geolocal – A New System for Geo-Referencing: Analysis of Base Distribution

“…Software was developed to demonstrate the algorithm for Geolocal and to perform simulations using practical examples with a representation of ground-based reference bases. The simulation performed by Kaufmann et al (2014) used, as ground bases, four cities in Brazil with known geodesic coordinates and synchronised clocks, and a receiver carried by an aircraft flying at an altitude of about 6 km over another city in the middle of the four bases. The results of this simulation demonstrated the method's functionality, with discrepancies in the repeater's position lower than 0·001 mm.…”

“…Following this trend, Brazil also has a work group developing a navigation system intended to be independent of current satellite systems without necessarily using navigation satellites for its purpose, named Geolocal. This new navigation system was conceived and patented by researchers of Mackenzie University (Kaufmann and Levit Kaufmann, 2012; Kaufmann et al, 2012, 2014; Pamboukian, 2012) and it is currently under the first phase of implementation.…”