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GPS, did you know? | The Apple Core | ZDNet.com
May 2nd, 2010
GPS, did you know?
It’s also worth noting that the iPad 3G, which comes with real GPS, began shipping this weekend. Coincidence?
Posted by Jason D. O'Grady @ 9:10 pm
Categories: GPS
Email Jason D. O'Grady
Tags: Satellite, GPS, Network Technology, Consumer Electronics, Personal Technology, Networking, Jason D. O'Grady
May 1, 2010 marked the 10 year anniversary of GPS for civilian use. On May 1, 2000 President Bill Clinton made a more precise GPS signal available for civilian use and changed the course of navigation forever.
Navigon, in a press release commemorating the anniversary noted a couple of fun facts about GPS. For example, did you know:
- Three satellites are needed to ascertain the position of a GPS receiver.
- It takes 24 satellites and several backup satellites orbiting the Earth at a height of over 20,000 kilometers, to ensure that three satellites are available anywhere in the world and at any time.
- Satellites transmit an uninterrupted signal detailing their current location and time, and it’s up to the GPS receiver to handle the signal delay with the help of an integrated clock to calculate its own position and speed.
- Using distance measurements from three points, known as trilateration, exact positions are determined. The signal from the first satellite determines the receiver’s degree of longitude; the second identifies the degree of latitude. As the receiver’s integrated clock is not accurate enough to measure the exact signal delays, the clock error is calculated using a third satellite and thus identifying the exact position.
Jason D. O'Grady is the editor of PowerPage.org, which has been publishing daily mobile technology news since December 1995. For disclosures on Jason's industry affiliations, click here or to view Jason's full profile click here.
Tip: David Morgenstern
Follow Jason on Twitter @jasonogrady.
GISuser:
Known as “selective availability”, this block was set up by the US government to prevent the military use of GPS by their enemies. Clinton’s decision to turn off the GPS interference signal helped mobile satellite navigation to finally make its breakthrough.
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