Home     Contact     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science     RSS     Terms of services     Privacy policy  
   
 Home      Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science   


<< Back to INDEX

What nuclear particles and general relativity has to do with your GPS? [Science]
posted February 12 2013 21:55.44 by Giorgos Lazaridis




Nuclear particles? What has to do with my GPS? One may ask. Well, first lets see how a GPS works. Any GPS needs at least 4 GPS satellites to operate. 3 of these satellites transmit a regular signal of their position in space, and the fourth satellite transmits a time signal. Your GPS will then trilaterate the position using these signals. But the time signal has to be very accurate, accurate down to the nano-second! And there is indeed one time-base generator that can achieve such an accuracy, the atomic clock. Using a canon that fires radioactive Cesium, the atomic clock can achieve extremely high accuracies. The rotation of the Earth itself actually is less precise than modern atomic clocks used as time standards.

You should read this article and watch the video to learn how the atomic clock works.



Image: Global Positioning System (GPS) Time Dissemination for Real-Time Applications by PETER H. DANA [link]


And what about general relativity? Einstein proved that time is not a constant through the universe. A clock that is placed in a higher altitude will run faster than a clock on the surface of earth. This effect is called "Gravitational time dilation", according to which, the lower the gravitational potential (the closer the clock is to the source of gravitation), the more slowly time passes, and the higher the gravitational potential (the furthest the clock is to the source of gravitation) the fastest time passes. Therefore, due to general relativity and gravitational time dilation, the clock on the GPS satellites has to be constantly compensated. Leaving the clock without this correction will result in positioning errors within 2 minutes, and every day this error will increase by 10km! Each nanosecond of time-error results into 0.3meter of distance-error. Each year, the clock of a GPS satellite is corrected by about 12 seconds! This would have resulted in a distance-error of roughly the size of Europe, from East to West!



[Link: Minute Physics]
 
Share



You might also like...


CO2 bike pump to Uzi [Hack]

Relax, Watching these Machines in Action...

Flying RC Model StarTrek USS-Enterprise NCC-1701-D [Project]

How to make a motherboard - a GIGABYTE Factory Tour

Thales' Theorem [Education]

Higgs Boson: The Inside Scoop [Physics]

A pinwheel calculator emulated by Arduino [Project]

How Good Is Facebook's Facial Recognition? [Entertainment]


<< Back to INDEX



Comments

  Name

  Email (shall not be published)

  Website

Notify me of new posts via email


Write your comments below:
BEFORE you post a comment:You are welcome to comment for corrections and suggestions on this page. But if you have questions please use the forum instead to post it. Thank you.


      

No comment yet...

Be the first to comment on this page!












 Contact     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science     RSS   

Site design: Giorgos Lazaridis
© Copyright 2008
Please read the Terms of services and the Privacy policy