What is GPS?

GPS, the Global Positioning System, is the only system today able to show you your exact position on Earth at any time, any where, and in any weather. GPS satellites orbit 11,000 nautical miles above Earth. They are monitored continuously at ground stations located around the world. The satellites transmit signals that can be detected by anyone with a GPS receiver.

The first GPS satellite was launched in 1978. The first 10 satellites launched were developmental satellites, called Block I. From 1989 to 1997, 28 production satellites, called Block II, were launched; the last 19 satellites in the series were updated versions, called Block IIA. The launch of the 24th GPS satellite in 1994 completed the primary system. The third-generation satellite, Block IIR, was first launched in 1997. These satellites are being used to replace aging satellites in the GPS constellation. The next generation, Block IIF, is scheduled for its first launch in late 2005.

Before we learn more about GPS, it’s important to understand something about navigation.