how does gps work, what is geocaching?

GPS •  history •  functionality •  accuracy

geocaching •  ? •  equipment •  conclusion

the journey

1973 U.S. Air Force & Navy decided to develop a satellite navigation system.

1974/79 System tests: Pseudolites and 11 Block I satellites

1979 Decision to expand the GPS system to 24 satellites.

1983 When a civilian airplane (Korean Airline) was shot down after it had gone lost over Soviet territory, it was decided to allow the civilian use of the GPS system.

1989/94 replacement with improved Block II satellites

1995 Full Operational Capability (FOC) is announced.

2000 deactivation of the selective availability and therefore improvement of the accuracy for civilians

2005 Launch of the first 2R-M GPS-satellite. January 2006: 28 satellites (oldest one Feb. 1989)

GPS - history

atomic clock

2R-M assembly Lockheed Martin

26.560 km from centre of earth

- 6.360 km earth radius ________ 20.200 km pathway-height MEO - "medium earth orbit"

GPS - functionality

true to scale

Monitor Stations - Hawaii

GPS - functionality Position Determination

I am satellite X, my position is Y and this information was sent at time Z.

distance

GPS - functionality

clock difference

•  Signals travel with the speed of light: c = 299 792 458,0 m/s

•  Time span between the satellite and the receiver lies in the range of 0.07 sec.

•  A clock error of 1/100 second would lead to a mistake in the position of about?

3000 km ! 2997924.58 m ;-)

•  To achieve an accuracy of 10 m of the position, the runtime of the signal must be precise to 0.00000003 seconds …

1983

GPS - accuracy

2000 Galileo… 2007

100

[m]

[year]

5 2

0.01

US Army …

SA (Selective Availability)

SA WAAS / EGNOS

DGPS (Differential GPS)

geocaching - ?

geocaching - ?

spoiler! :-/

geocaching - ?

Implosion Meteor solarthermienator

-

cachenote

geocaching - ?

cache content

•  Log-book •  Pencil •  Cachenote •  Trade stuff •  Deed of FTF

….

geocaching.com

Log our visit!

geocaching - equipment

=> GPSr •  Compass •  Map •  Cache Bag •  PDA •  Location •  Stuff to Stash (trade) •  Container (waterproof) •  Micro-caches •  Hiking Staff •  special equipment like: scuba gear, things for climbing …

geocaching - conclusion

•  Find places you’ve never been or recognised before. •  Do outdoor sports with a mission in background. •  Enjoy the beautiful nature ...

... and protect her!

chief source of information

Global Positioning System: http://en.wikipedia.org/wiki/Global_Positioning_System http://www.kowoma.de/en/gps/index.htm

Pictures and Art: http://www.deviantart.com/ http://www.lockheedmartin.com/GPS/

Geocaching: http://www.geocacher-u.com/ http://www.geocache.at/ http://www.geocaching.com/