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GPS – Global Positioning System

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					    Tree
Identification
  Using GPS
GPS - Global Positioning System




   What   is GPS and how does it work?
         GPS –        Global Positioning System

   Developed for use by the
    U.S. military at the end
    of the cold war to track
    ICBM missiles.
   Fully operational 1995
    (selective availability
    turned off May 1, 2000)


           Original Manpack developed
           for use by military
        GPS –        Global Positioning System

 24 satellites orbit 22,200
  km from earth, with five to
  eight satellites always visible
  from any point on earth
 GPS receiver needs to make
  contact with signals from
  three satellites in order to
  find a location on earth
 Contact with a fourth
  satellite allows for
  determination of elevation
  above sea level
GPS –   Global Positioning System
          GPS –       Global Positioning System

   Cost of GPS receivers from $100 for hand-held unit
    (accurate within 10 meters horizontally) to over
    $50,000 for research receivers (accurate within 1 cm
    horizontally)
   Used extensively for marine and air navigation and
    mapping. Growing popularity of GPS use by hikers,
    hunters, fisherman, and gamers.
   Scientific uses include atmospheric studies, plate
    tectonics, including mapping of volcanoes, and collection
    of coastline data
   No cost to use the system
        GPS –         Global Positioning System

 1.GPS technology relies on the use of satellites.
 2.To locate a satellite, a GPS receiver measures
  distance using the travel time of radio signals
 3.To measure travel time, GPS needs very accurate
  timing which it achieves with some tricks.
     • Along with distance, you need to know exactly where the
       satellites are in space.
     • False code signals are created, one which the satellite
       signals, and one that the GPS matches. When the two
       signals “line up”, the time is determined. The GPS emits a
       radio frequency, similar to the MHz on your radio, which
       increases the accuracy of the GPS.
     • Finally you must correct for any delays the signal
       experiences as it travels through the atmosphere.
GPS –   Global Positioning System
         GPS –      Global Positioning System

How Do You Use a GPS?

     Each brand of GPS is set
      up differently.

     At the Smith Center, we
      use Garmin etrex units.
         GPS –   Global Positioning System

  Internal GPS
    Antenna                          PAGE Button
 UP Button
 DOWN Button
                                     POWER
ENTER Button                         Button




                                  LCD Display with
                                  Backlight
         GPS –       Global Positioning System

The GPS receiver displays pages with separate
 functions.
     There are four main pages that you will be using to
      navigate:
          GPS –      Global Positioning System

Let’s Get Started!

   All GPS receivers operate on information gathered from
    satellites. In order to receive the satellite signals,
    you must be outside, away from any objects such as
    trees or overhangs that might block the signal. You
    need a clear view of the sky.
     GPS –      Global Positioning System


Step 1: Push and hold
down the POWER
BUTTON to turn the unit
on. You’ll see the
“Welcome” page for a few
seconds, followed by the
Satellite Page.
          GPS –       Global Positioning System

How do I know I’m ready
 to go?
   When you see the “Ready to
    Navigate” message, you know
    the etrex has locked onto
    the satellite signal.
   This must be displayed
    before you can begin using
    the GPS to navigate.
   Signal strength bar will be
    filled in to indicate the GPS
    has locked onto signal.
          GPS –       Global Positioning System

Satellite Page Basics:
   Two display pages:
    Normal Skyview that
    shows the satellites,
    satellite signal strength,
    and estimated accuracy.
    Advanced Skyview that
    shows you the numbered
    satellites being used, the
    proximity and horizon and
    sky overhead.
          GPS –      Global Positioning System

What does the MAP
 page do?

   The map page shows
    where you are and uses
    an animated figure to
    show where you are
    actually going.
   Waypoint names and
    symbols are also shown.
          GPS –      Global Positioning System

Map Page Basics:

   You can change the map
    scale by pressing and
    holding the UP button to
    view a larger area, or
    the down button to view
    a smaller area.
   You can change the scale
    from 200 ft to 800 miles
    to view your entire trip!
         GPS –       Global Positioning System

NAVIGATION PAGE
 BASICS
   The Navigation Page guides
    you to your destination. It
    shows you your moving
    direction and speed. If you
    have a specific destination
    entered into the GPS, the
    page shows you the name of
    the location, the distance
    and displays a direction
    arrow that is shown in the
    compass ring.
     GPS –      Global Positioning System

NAVIGATION PAGE BASICS:

We’ll be using LATITUDE and LONGITUDE
 coordinates to describe locations.

Latitude measures distances North or South from
  the Equator (0°) towards the Poles. (90°)
     GPS –      Global Positioning System

NAVIGATION PAGE BASICS:

We’ll be using LATITUDE and LONGITUDE
 coordinates to describe locations.

Longitude measures distances West or East from
  the Prime Meridian (0° at Greenwich, UK).
GPS –   Global Positioning System




    Lines of Longitude
GPS –   Global Positioning System




    Lines of Latitude
GPS –   Global Positioning System




         Combined!
      GPS –    Global Positioning System


                     The units that we will be
                     using to measure are:
                        Degrees (°)

North 39° 06 .582’      Minutes ( ‘ )
                         And . . .
West 77° 06 .086’       THOUSANDTHS of
                        Minutes!
         GPS –       Global Positioning System

MAIN MENU BASICS:

   With the main menu you
    can create waypoints,
    routes, save and view
    your track logs. If you
    select MARK, you can
    mark your location as a
    waypoint.
       GPS –       Global Positioning System
GOING TO A WAYPOINT:
 Press the PAGE button and switch
  to the MENU Page
 Press UP or DOWN and highlight
  WAYPOINTS. Press ENTER..
 Press the UP or DOWN button
  and highlight the alphabetical tab
  for the waypoint. Press ENTER.
 This will take you to a list of
  waypoints.
 Highlight a waypoint, and press
  ENTER.
         GPS –     Global Positioning System

   REVIEW WAYPOINT
    page appears. REVIEW
    WAYPOINT allows you to
    change coordinates,
    name, symbols, and
    delete waypoints.
   On the REVIEW
    WAYPOINT page, press
    the UP or DOWN button
    and highlight GOTO,
    press enter.
  GPS –   Global Positioning System




Using GPS Technology to
      Locate Trees
       GPS –     Global Positioning System



 GPS technology allows us to identify locations
  of specific trees
 Useful in monitoring health of trees over time
 Latitude and longitude coordinates are given for
  each tree location
    GPS –   Global Positioning System

GOING TO A WAYPOINT


                   It would be VERY
                   difficult to use the GPS
                   Unit by itself to find your
                   way to your waypoint, so
                   you will also need to know
                   how to use. . .
GPS –   Global Positioning System

                A Map!

                Use the map to look for
                  landmarks, to stay on
                  trails, to gauge
                  distances, and to find
                  your way back!
          GPS –       Global Positioning System

STEPS TO USING THE GPS:
   From the SATELITE page, press the PAGE button until
    you come to the MENU page.
   Scroll down to WAYPOINTS, press ENTER.
   Scroll down to the tree waypoint entered. Press
    ENTER.
   The REVIEW WAYPOINT screen will appear, select GO
    TO, the COMPASS page will appear.
   Begin walking. The arrow will reorient in the direction
    you should be walking if you could walk a straight line to
    your waypoint. You WILL need to adjust your line of
    travel to avoid obstacles and to remain on trails.
       GPS –     Global Positioning System

STEPS TO LOCATING THE TREE:


 Follow the arrow and stay on trails to find
  desired coordinates. Remember that the GPS is
  only accurate within 10 meters. At this point
  you need to begin looking for the tree marker.
 At this point, you will need to spread your
  group out and look for the tree marker.
       GPS –      Global Positioning System

ONCE YOU’VE FOUND THE TREE:


 Use the dichotomous key to identify the tree.
 Check your identification using a field guide to
  North Eastern trees.
 Enter the next tree number and coordinates
  that you wish to locate as a GPS waypoint.
 Continue to the next tree.
         GPS –       Global Positioning System

THINGS TO KEEP IN MIND:

   Do not cross roads (except Meadowside Lane)
   Stay on trails. No bushwhacking!
   You may need to go around rocks or cross streams.
   Stay together – do not leave your group
   Use your map and compass in conjunction with the GPS
   Respect the park. Take only your memories, leave only
    your footprints.
          GPS –       Global Positioning System

   IMPORTANT POINTS:

   GPS technology is limited – tree canopy and cloud cover
    affect signal strength
   Be aware of your direction of travel. Use a map.
   Watch the time! Return on time!

				
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posted:12/4/2011
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