GPS Global Positioning System

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GPS Global Positioning System

• Wolfgang Leister

Translated and adapted by Beate Heilemann May 2006
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GPS (Global Positioning System)
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How does GPS work ?

• Introduced in 1973 in USA for military purposes
• 24 satellites, which send
• signals and their own
• positions
• Receiver which
• receives signals
• from several satellites

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GPS Receiver

• Receives signals from several satellites
• The positions of the satellites are known
• GPS receivers calculate theircurrent position
  and the precise time
• The GPS receiver calculates its own position
• Convertes to degrees or UTM

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When does GPS work?

• Your GPS must have free visibility to at least 3
  satelittes (Works much better with 4)
• (3 satellites unreliable and without height
  measuring)
• The satellites schedule must be known
• Trees (forest), walls (tall buildings), mountain
  slopes, certain weather conditions all these
  can confuse your GPS
• Your GPS needs power! Always Remember batteries!

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Where can I start my GPS

• Indoors ?
• Not possible
• In car, bus, train?
• Limited possibilities, but possible by the
  windows
• Takes a long time, but does work in general
• In towns and cities
• Limited visibility to the sky
• Takes a long time to warm up
• Not precise (ca. 100 meters divergence)

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CoordinatesThe 2 mostly used coordinate systems
worldwide

• UTM (Universal Transverse Mercator)
• Grades / minutes/ seconds (the Nautical
  coordinate system)
• Local coordinate systems (out-dated)
• German Grid, Swedish Grid, NAD, ED etc. etc
  etc.etc..
• Where is the referanse?(In the left corner)

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UTM

• Universal
• Transverse
• Mercator
• 60 x 6 stripes

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UTM

• In the middle 500 000
• Measured in meters in both directions

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What does the position show us?
N 4303.150 E 07428.317

• Degrees (nautical coordinates)
• UTM ( Universal Transverse Mercator) (metric
  coordination system)
• Better for use on land
• This is at Manas air base!

43T E 0456996 UTM N 4766780
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GPS-use in Practice

• Which functions are pliable in the mountains?
• Cases
• Where am I?
• How far is it to ...?
• How do I get to ...?

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Turn on the GPS ...

• Turn on the on/off-button
• Wait for the satellites
• 2D Nav
• 3D Nav
• Preciseness
• GPS can be used when the precision is good enough

• Always check if the answer from your GPS makes
  sense!!!
• Check the map datum
• Check the coordinate system

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Read and save positions

• Actual position
• Shows directly
• Saves as waypoint
• New position
• Mark and edit

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Save the position

• You need
• GPS
• MAP

• Turn on the GPS
• Read the coords from the map and log your GPS
• Or Mark when you are visiting the spot

32V 0596700 UTM 6649260
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Direction

• When you are MOVING the GPS can calculate the
  direction.
• GOTO function show with an arrow in which
  direction you must go.
• Held the GPS in the correct direction.

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Case from the Norwegian mountainsTick fog at the
hilltop St. Pål

• Fog at the hilltop St. Pål, visibility 20 meters
• Snow-covered without tracks or trail marks
• Read the coords to Klemsbu (shelter) at the map
• Log as waypoint
• Push Goto and choice Klemsbu
• Follow the arrow (but be aware of steep slopes
  and cliffs)

Geiteryggen (Staffed cabin)
Snow /Fog
St. Pål
Klemsbu (shelter)
Finse (Staffed cabin)
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Digital maps

• You can buy digital maps (on CD) and download to
  you GPS. Expensive at last in Norway. The
  Oslo-area costs 100.-
• Warning. Use ordinary maps as well. The display
  on your GPS is not good enough for overall views.

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Where are the traps?

• Wait till you have got sufficient satellites
  Sometimes the satellites are in a unfavourable
  position
• Wait a bit and check that the accuracy is ok
• NB Be aware of typing in wrong ciphers
• Check that you have got updated information.
• (sometimes this can take quite some
  time...)Remember. Batteries dont last for ever.

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Good advices

• Always bring with you map and compass!
• Use the ruler on the compass to read the coords
  on the map!
• Do not rely too much on altitude measuring,
  speed,
• direction, time of arrival
• Using you GPS when walking Easy to stumble!!!
• Remember the GPS is calculating air line. Mind
  the terrain (steep slopes, rivers and other
  obstructions)
• Always have extra sets of batteries with you

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Use of GPS in the forest north of Oslo -
Geocaching
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GPS tour on one of lakes east of Oslo
www.geocaching.com
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GPS use on horseback. In Trøndelag
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Fun to use your GPS in the mountains!!! At the
western part of Norway