Global Positioning System (GPS)

GPS is quite common nowadays. It can be found in cars , taxis and in handheld. Recently, on a kayaking trip into the Ubin Mangrove ( see previous posting), one of us brought a handheld GPS; it showed the route we travelled into the mangrove! no need to be afraid of getting lost - cool.

Depending on devices, the accuracy can go up to 10m. Although for military use, with super duper computers, accuracy up to mm is possible. Imagine locating a mm spot anywhere on Earth!!!

Beside civilian uses, it is also used in military, for example to cruise missiles and precision-guided munitions.
For more applications of GPS:
http://en.wikipedia.org/wiki/GPS_applications


Do you know?

1. GPS is owned by the United States and is allowed for public use ( in 1996 during Bill Clinton's presidency) .
   
2. It works by 24 satellites orbitting round the earth.
   
3. You need to communicate to at least 4 satellites to 'log on' your position.
   
4. To compute such precise timing in such a big distance, GPS needs Einstein's General Theory of Relativity.( to account for the gravitational redshift)
5. And US can choose to shut the system down ... and there goes our taxi booking ...
   
6. A few other countries are trying come out with their own Global Navigation Satellites System. They are

• Beidou by China
• Galileo by EU
  
• Glonass by Russis
• Indian Regionaly Navigational Satellite System by India (regional)