When we talk about the "global positioning system" or GPS, we usually mean the NAVSTAR-GPS satellite constellation — the NAVigation System with Timing and Ranging — Global Positioning System. NAVSTAR-GPS belongs to the U.S. Department of Defense, has 24 working satellites and is used by all satellite-based earthmoving systems.
Orbiting some 4,000 miles farther out in space, however, at an altitude of about 16,000 miles, is the GLONASS constellation. The GLObal NAvigation Satellite System is being established by the Russian government, which, on Christmas Day 2005, launched three additional satellites to bring the present GLONASS system to 17 working units. The plan is to complete the system with a total of 24 satellites within the next two years.
Three days after the GLONASS launch, the Russian Federal Space Agency lent a hand to the European Union (EU) by launching that organization's first satellite in what will be the 30-satellite Galileo constellation. The EU reportedly will allocate an initial $1.2 billion during the next several years to fund deployment of the new global positioning system, which is designed to be compatible with the NAVSTAR system.
How might all these additional satellites affect machine-control systems installed on earthmover machines?
According to Ray O'Connor, CEO of Topcon Positioning Systems, more satellites are the means to more precise, more reliable machine-control systems. Constant access to a minimum of five satellites is critical for precise operation of these systems, he says, and the more satellites available to the user, then the less downtime and signal degradation that will be incurred and the more work that can be completed without interruption.
Topcon presently sells machine-control systems that can utilize both the NAVSTAR and GLONASS constellations, and recently announced a new Paradigm-G3 chip that will have the capability to process signals from all three constellations.