GPS Global Positioning System Why Do I Care? Since the beginning of recorded history there is evidence that people used indirect methods, like the stars, to navigate. Although this was the most efficient and accurate method available at the time, knowing the exact position of one’s location or a specific place was not yet possible. The technological advancement of GPS has made this possible, and, in so doing, changed the way that people interact with their environment, communicate, and conduct business. If it were not for sophisticated global positioning systems many of the tasks we have become accustomed to in our daily life would not be possible, i.e., the use of emergency response vehicles, cell phone usage, and recreational activities. What is GPS? (1) Global Positioning System a global navigation satellite system which consists of a series of 29 medium Earth-orbiting satellites called a constellation 24 active 5 in reserve technology began development in the early 1970’s U.S. Department of Defense the modern constellation was not fully functional and in orbit until 1995 civilian use allowed by President Bill Clinton in 1996 What is GPS? (2) GPS helps the military accurately blow up stuff helps you get to wherever you want to go (much less fun) How Does GPS Work? (1) for accurate GPS data you need a quality GPS receiver that can locate at least three satellites in the constellation the more satellites the more accurate the data is each satellite constantly transmits a signal that sends the following information to Earth the time the message was sent (atomic clock) precise orbital information (location in the sky) the operational status of the satellite and orbital location data transmitted from the satellites is then picked up by the receiver which “tri-laterates” its position by calculating the time it takes to get the high frequency low power radio signal from the satellites the speed of this signal is already known How Does GPS Work? (2) What is GPS Used For? mapping remote sensing surveying transportation military planning navigation Another Explanation… From The NASA Sci Files: How GPS Works Your GPS Unit (1) Power Button Thumb Stick LCD Display Menu Your GPS Unit (2) use the Thumb Stick to navigate the menus satellites your receiver is picking up: black = good this is the option you use to mark your points the latitude and longitude you are currently at Satellite Menu: this is the default menu that you will use to navigate to the lat/longs Main Menu: this is where you will select the “Mark” option to mark your location Your GPS Unit (3) LET’S GO OUTSIDE!