The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. (Ground Stations - These stations monitor the GPS satellites, checking both their operational health and their exact position in space. The master ground station transmits corrections for the satellite's ephemeris constants and clock offsets back to the satellites themselves. The satellites can then incorporate these updates in the signals they send to GPS receivers. There are five monitor stations: Hawaii, Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs) GPS uses these "man-made stars" as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter! In a sense it's like giving every square meter on the planet a unique address. GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. And that makes the technology accessible to virtually everyone. These days GPS is finding its way into cars, boats, planes, construction equipment, movie making gear, farm machinery, even laptop computers. Dave Goodman The GOODMAN Clearinghouse http://www.bcpl.net/~dmg Baltimore PC Users Group http://www.baltimorepcug.org Baltimore County Genealogical Society http://www.serve.com/bcgs/bcgs.html ----- Original Message ----- From: <Poppy0206@aol.com> To: <VAROOTS-L@rootsweb.com> Sent: Saturday, October 04, 2003 8:29 AM Subject: Re: [VAROOTS] GPS - Cemeteries - Virginia > May I ask what a GPS is please? > > chris > > > ============================== > To join Ancestry.com and access our 1.2 billion online genealogy records, go to: > http://www.ancestry.com/rd/redir.asp?targetid=571&sourceid=1237 > > >