1. 1. 10 things You need to know About GPS
2. 2. Definition The Global Positioning System (GPS) is a space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the earth where there is an unobstructed line of sight to four or more GPS satellites. 1
3. 3. The Generic Term The generic term for these systems is Global Navigation Satellite System, GNSS. There is such systems as Russian`s GLONASS, USA`s GPS, European project Galileo, etc. 2
4. 4. How GNSS Works 3 The satellites orbit around earth and broadcast information. That information is basically a time stamp.
5. 5. GNSS Receivers Receive GNSS receivers do not have two-way communication with the navigation satellites; the satellites are broadcast-only. 4
6. 6. GNSS is not Great at Elevation Horizontal accuracy for recreational/consumer devices and many cell phones is about +/- 10 meters (within a tennis court) while vertical accuracy can be two or three times that, about +/- 20 or 30 meters. The cause of this relies to geometry. 5
7. 7. Assisted GPS With multiple GNSSs online, or coming online, and a variety of non-GPS locating technologies in use (wi-fi, cell tower, etc.), theres an effort to bring them together for enhanced solutions. 6
8. 8. GPS Interference Because GPS signals from satellites are very weak radio signals, they are susceptible to interference by natural and man-made signals. 7
9. 9. Government Control of GPS While the U.S. Department of Defense developed and operates GPS, it serves a wide range of civilian users. To date, the Department of Defense has never shut off GPS in any part of the world, for any reason. 8
10. 10. Navigating by GNSS The GNSS only provides information to a receiver to determine its current location, velocity and time. Any other information, such as the direction of motion, a suggested route to a destination, a map, is provided by software algorithms and stored map data. 9
11. 11. The GPS is Wrong! Most of the time a GPS receiver is correct in determining its position, within its tolerance. If a navigation system fails to provide an accurate route, other things are more likely to be the culprit, for example: poor algorithm out-of-date street network wrong destination address The U.S. government received so many complaints on this matter it compiled an article to explain to users how to fix such errors. 10
12. 12. This is the end