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O P E R AT I N G S T R AT E G I E S Installing Leica Geosystems' terrestrial Jps LocataLites at strategic points around the Boddington pits reportedly eliminated the mine's complete reliance on steady GPS coverage for drill-rig guidance in the deepest mining areas. and efficiency improved dramatically after the Jps system was commissioned. Dr. Brendon Lilly and Stuart Gray of Leica Geosystems, collaborating with the Locata team and John Carr and James Earl from Boddington, authored a report released in August 2012 describing the www.e-mj.com Leica Jps components and their deployment at the mine. As explained by the authors, the installation comprises two main components: the Jps LocataLites, which are the transmitters positioned around the mine pit; and the Jps receivers mounted on the machines. The Jps LocataNet is the "local constellation" network made up of a number of Jps LocataLites. In this network, one of the Jps LocataLites is assigned Master status and the rest are assigned as slaves. The slaves 'TimeLoc' to the Master. The Master also contains a meteorology station that measures and transmits pressure, temperature and humidity data around the LocataNet so that it can be used in positioning computations. The paper noted that, although the GNSS satellite constellations and the Jps LocataNet have extremely accurate, yet independent time bases, it is far more convenient for the integration of GNSS+Locata combined positioning solutions if the time bases of each system are closely aligned. Locata developed a method to slew its internal time base to precisely align with the GNSS timebase (and hence the global-standard UTC time). When temporal alignment is achieved, the combined solution algorithm does not have to correct for the time offsets between systems. Leica Geosystems has integrated this capability into the Jps LocataNet and Jps receivers, allowing the complete Jps LocataNet to synchronize FEBRUARY 2013 • E&MJ; 77