WORKING WITH NAVSTAR GLOBAL POSITIONING SYSTEM SATELLITES AND THE GARMIN PLUS III GLOBAL POSITIONING

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AGENDA

• 730 Check-in/Registration, Continental Breakfast
  
• 800 OVERVIEW OF THE NASA/RAYTHEON SYNERGY
  PROJECT
• 830 DATA COLLECTION
• 850 ABOUT THIS WORKSHOP
• 910 THE NAVSTAR SATELLITES HOW GPS WORKS
• 930 WORKING WITH THE GARMIN GPS III PLUS GPS
  distribution
• 1015 BREAK
• 1030 WORKING WITH THE GARMIN GPS III PLUS
  (Continued)
• 1130 GPS UNIT INITIALIZATION OVERVIEW FIRST
  WAYPOINT
• 1215 LUNCH On-site
• 1245 FIELD WORK WAYPOINT DATA COLLECTION
  Supervised by mentors
• 130 LABORATORY ACTIVITY WAYPOINT DATA REPORTING
  
• 230 BREAK
• 230 WAYPOINT DATA REPORTING (Continued)
• 315 MEMORANDUM OF AGREEMENT
• 330 LANDSCAPE CHARACTERIZATION PROTOCOL
• 345 GPS in the Classroom A Report on Student
  Activities
• 405 FOLLOW-UP ACTIVITIES LONG-TERM RELATIONSHIP
• 420 WORKSHOP EVALUATION AND CLOSING ACTIVITIES

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WORKING WITH NAVSTAR GLOBAL POSITIONING SYSTEM
SATELLITES AND THE GARMIN III PLUS GLOBAL
POSITIONING SYSTEM UNIT
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Orbits

• THE NAVSTAR SATELLITES HOW GPS WORKS

Altitude 20,200 km 12,552 sm 10,915 nm
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THE NAVSTAR SATELLITES HOW GPS WORKS
Locational accuracy

• Satellite distribution varies depending upon the
  time of day
• Affects the signal acquisition time
• Impacts positional accuracy

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THE NAVSTAR SATELLITES HOW GPS WORKS

• What a GPS Does
• Calculates the intersection of measured distances
  (ranges) from several satellites to a receiver
• Trilateration
• Triangulation
• Measures distances by determining travel time
  intervals for signals from satellite to receiver
• Combines distances and reported satellite
  positions to calculate receiver position and time

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THE NAVSTAR SATELLITES HOW GPS WORKS

• How it Does It
• Measures how long a coded radio signal takes to
  reach receiver from satellite
• System assumes that both satellite and receiver
  generate code at exact same time
• Receiver compares how late the satellites code
  appears relative to its code to fix time of
  travel
• Calculates distance traveled by multiplying
  travel time by speed of light

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THE NAVSTAR SATELLITES HOW GPS WORKS

• Time Is Critical
• 0.000 000 003 340 seconds to resolve one meter
  (334 one hundred billionths sec.)
• One nanosecond of time error equals approximately
  0.3 meters (0.984 feet) range error
• Precision timing and frequency control are
  essential to GPS system
• Cesium and rubidium atomic clocks used to keep
  satellite time standards

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THE NAVSTAR SATELLITES HOW GPS WORKS

• Sources of GPS Error
• Ionosphere and Troposphere delays
• Predicted satellite orbit irregularities
• Intentionally introduced error (Selective
  Availability)
• Poor satellite coverage
• Poor collection practices (Multipath)

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THE NAVSTAR SATELLITES HOW GPS WORKS

• Dilution Of Precision (DOP)
• The effect of satellite geometry on position is
  expressed by geometric dilution of position
  (GDOP) parameters
• PDOP - 3D dilution of precision in position
• HDOP - 2D dilution of precision
• VDOP - vertical dilution of precision
• TDOP - time dilution of precision

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THE NAVSTAR SATELLITES HOW GPS WORKS

• Poor GDOP
• Results when angles from receiver to the set of
  SVs used are similar

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THE NAVSTAR SATELLITES HOW GPS WORKS

• Good GDOP
• Angles from receiver to SVs are different

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THE NAVSTAR SATELLITES HOW GPS WORKS

• Caused by reflected signals from surfaces near
  the receiver that interfere with signals
  following straight line from satellite
• Buildings
• Other structures
• Trees
• GPS User

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Multipath Errors

• Multipath Errors
• Caused by reflected signals from surfaces near
  the receiver that interfere with signals
  following straight line from satellite
• Buildings
• Other structures
• Trees
• GPS User

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WORKING WITH THE GARMIN GPS III PLUS

• What Is The III ?
• Hand-held, autonomous (stand alone) GPS receiver
  (DGPS ready)
• 12 channel receiver - can receive signals from 12
  satellites at the same time
• Battery powered (36 hours claimed 22 hours
  actual 10 year Lithium for data)
• Claimed horiz. accuracy - 15 meters (49 feet)
• Actual results - 3.08 meters (10.1 feet)

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WORKING WITH THE GARMIN GPS III PLUS
Garmin GPS unit orientation
Horizontal Vertical
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WORKING WITH THE GARMIN GPS III PLUS

• GPS Handout Time
• 1) Mentors distribute GPS Units (serial cable in
  box), software, GPS carrying case and Memorandum
  of Agreement (MOA).
• 2) Log Serial Number on MOA.
• 3) Return completed MOA to Mentors.

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WORKING WITH THE GARMIN GPS III PLUS

• MEMORANDUM OF AGREEMENT (DRAFT) BETWEEN
• THE MARYLAND SPACE GRANT CONSORTIUM
• AND TEACHERS PARTICIPATING IN THE
• NASA/RAYTHEON/TOWSON UNIVERSITY CENTER FOR
  GEOGRAPHIC INFORMATION SCIENCES
• SYNERGY PROJECT (PHASE II)
• The Maryland Space Grant Consortium (MSGC),
  through its partnership with the Towson
  University Center for Geographic Information
  Sciences (TU CGIS), agrees to provide a GARMIN
  GPS III Plus Global Positioning System (GPS)
  receiver and ancillary equipment to each teacher
  successfully completing a one-day Synergy Project
  (Phase II) workshop.
• Each teacher receiving the GPS receiver and
  ancillary equipment agrees to provide the
  following services in return
• Use the GPS receiver to collect and report
  selected ground truth data in accordance with the
  instructions outlined in the attached "Landscape
  Characterization Protocol.
• MSGC and TU CGIS agree to
• Grant ownership of the assigned GPS receiver and
  ancillary equipment to the teacher and his/her
  school.
• Provide support to the teacher via the Internet
  and/or telephone for technical questions related
  to the use of the GPS receiver and ancillary
  equipment.
• The following restrictions apply
• If the teacher does not collect and report ground
  truth data in accordance with the instructions
  outlined in the attached "Landscape
  Characterization Protocol," he/she will be asked
  to return the GPS receiver and ancillary
  equipment to MSGC.
• If a teacher moves from one school to another in
  the same county he/she may take the GPS receiver
  and ancillary equipment with him/her to the new
  school. However, if the teacher moves to a
  school in a different county, or if the teacher
  retires or leaves teaching for some other
  profession, the GPS receiver and ancillary
  equipment must remain at the school listed below.
  The teacher must notify MSGC in writing within
  thirty (30) days of the intent to move the GPS
  receiver and ancillary equipment from the school
  listed below (or if he/she retires or leaves
  teaching).

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WORKING WITH THE GARMIN GPS III PLUS

• This Memorandum of Agreement signed December 8,
  2001 contains the entire agreement between the
  parties and may not be changed or amended except
  in writing and signed by the parties designated
  below
• ____________________ __________________________
  ____
• Dr. John M. Morgan, III Teacher (sign name)
• Professor and Director
• Center for Geographic Information
  Sciences ______________________________
• Towson University Teacher (print name)
• ____________________ __________________________
  ____
• Anne Anikis Name of School
• Assistant Director
• Maryland Space Grant Consortium _________________
  _____________
• Street Address
• ____________________
• GPS Unit Registration
  ______________________________
• City, State, Zip
• ______________________________
• Email address

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WORKING WITH THE GARMIN GPS III PLUS

• A. INSTALL BATTERIES
• (4 size AA alkaline batteries needed)
• Open battery compartment 
• Raise ring at base to open lid (may need a sharp
  instrument to raise it) 
• Press down lightly and twist ring ¼ turn
  counterclockwise 
• Insert batteries, noting polarity 
• Close battery compartment 
• Press lid down lightly and twist ring ¼ turn
  clockwise

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WORKING WITH THE GARMIN GPS III PLUS
Garmin GPS Pages
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WORKING WITH THE GARMIN GPS III PLUS

• B. POWERING UP THE UNIT
• Press red Power/Backlight key to turn unit on
• Welcome Page is displayed automatically

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WORKING WITH THE GARMIN GPS III PLUS

• Warning Page is displayed automatically

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WORKING WITH THE GARMIN GPS III PLUS

• Satellite Status Page is displayed automatically

• 2D Navigation (Horizontal only)
• 3D Navigation (Horizontal and Vertical)
• Estimated error
• Predicted satellite positions
• Signal strength
• Battery strength
• Satellite geometry (DOP)

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WORKING WITH THE GARMIN GPS III PLUS

• A message will inform you that the unit is
  Searching the Sky or Need To Select
  Initialization Method.
• For the Former
• Press Enter to acknowledge message. Actual
  initialization must be performed outdoors.
• For the latter
• Press Enter to acknowledge message.
• Select None for initialization method.
•  

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WORKING WITH THE GARMIN GPS III PLUS

• C. START SIMULATOR (This function for training
  purposes only)
• Press Menu
• Start Simulator will be highlighted at top.
• Press Enter
• Press Enter again to acknowledge warning message
  and display Satellite Status Page.
• Press Page slowly to observe the next five pages
  displayed on this GPS
• Position Page
• Active Route Page
• Map Page
• Compass Page
• Highway Page
• Satellite Status Page

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WORKING WITH THE GARMIN GPS III PLUS

• DISPLAY OPTIONS
• Continue to press Page until Map Page is again
  displayed
• Orient displayed page horizontally, then
  vertically 
• Press and hold Page key for two seconds. Repeat,
  if necessary, to get vertical orientation.
•  
• Increase map size by deleting data fields 
• With Map Page showing, press Menu to display Map
  Page options 
• Highlight Data Fields Off 
• Press Enter

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WORKING WITH THE GARMIN GPS III PLUS

• D. STOP SIMULATOR 
• Press Menu
• Stop Simulator is highlighted at top 
• Press Enter  

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WORKING WITH THE GARMIN GPS III PLUS

• E. STEP BY STEP MADITORY SETUP FOR WAYPOINT DATA
  COLLECTION
•  
• Select Main Menu (Press Menu twice)
• Use Rocker Keypad to
• scroll down to Setup 
• Press Enter

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WORKING WITH THE GARMIN GPS III PLUS

• To view setup options for the first time, scroll
  horizontally to the right to see file tabs listed
  below
•  
• System Units Timers Time Position Interface
• To Edit Options  
• Scroll horizontally to the left to return to and
  highlight the System tab
• Press Enter

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WORKING WITH THE GARMIN GPS III PLUS

• System
• Scroll down to Power Saver
• Enter to see options
• Scroll to
• On (Power saver mode)
• Enter to select

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WORKING WITH THE GARMIN GPS III PLUS

• Units
• Scroll down to Distance and Speed
• Enter to see options
• Scroll to Statute - Enter
• Scroll to Heading
• Enter to see options
• Scroll to True - Enter
• Scroll to Altitude/Elevation - Enter
• Scroll to Feet - Enter

(AMSL) or perhaps above ellipsoid
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WORKING WITH THE GARMIN GPS III PLUS

• Timers
• Battery timer
• On (Select when new batteries are placed in the
  unit to track battery life optional)

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WORKING WITH THE GARMIN GPS III PLUS

• Time
• Scroll down to Time Format
• Enter to see options, scroll to choose Local 12hr
  or local 24hr, Enter to select
• Scroll to LTZ, Enter to select, use keypad to
  enter time difference. Eastern Daylight Savings
  Time is four hours behind UTC
• Eastern Standard Time is five hours behind UTC
• Do not adjust time or date

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WORKING WITH THE GARMIN GPS III PLUS

• Position
• Scroll down Position Format
• Enter to see options
• Scroll to hddd.ddddd
• Enter to select
• Scroll to Map Datum
• Enter to see options
• Scroll to NAD83
• Enter to select

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WORKING WITH THE GARMIN GPS III PLUS

• Interface
• Important for data transfer
• Scroll to Format, Enter to see options, Scroll to
  Garmin, Enter to select
• Scroll to Transfer Mode, Enter to see options,
  Scroll to Host, Enter to select

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III. UNIT OPERATIONS AND OPTIONS

• A. Simulator Dry Run (Follow along in Simulator
  Mode)
• Average Position (Recording Positions)
• Enter Waypoint
• Edit Waypoint
• Delete a Waypoint
•  

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III. UNIT OPERATIONS AND OPTIONS

• Initialization (starting point for first field
  work activity)
• Orient the receiver to our position (only done
  once)
• Press Enter to acknowledge message.
• If asked for Init Method select Use Map.
  other wise
• Press Menu and highlight Initialize Position,
  press Enter
• Use the rocker keypad to move the map cursor
  (light brown arrow) to your city or town.
• Use Zoom keys (In or Out) to make it easier to
  locate your city or town.  
• Press Enter

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III. UNIT OPERATIONS AND OPTIONS

• Initialization (Starting point for real data
  collection)
• Outside
• Open area, clear view of sky
• Antenna up
• Welcome Page, Warning Page, Satellite Status Page
• Acquiring Satellites
• Receiver has fix when it transitions from
  Satellite Page to Map Page. Quit to return to
  Satellite Page

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III. UNIT OPERATIONS AND OPTIONS

• Recording Positions Requirements
• Select field observation point
• Estimate center of area if possible
• Turn on receiver hold unit at eye level,
  position antenna up and away from obstructions
• Acquire satellite signals
• Need four for 3D location
• Check DOP and EPE

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III. UNIT OPERATIONS AND OPTIONS

• Recording Positions Requirements
• From the Satellite Position Page ensure the
  following
• DOP lt 6.0 (Typically less than 2.0)
• Make sure you have good satellite coverage
• Minimum measurement count 20
• You must take an averaged position reading

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III. UNIT OPERATIONS AND OPTIONS

• Average Position Menu
• Page to Position Page
• Press Menu
• Highlight Average Position
• Press Enter
• Average Position Page will appear
• Estimated Accuracy
• Measurement Count

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III. UNIT OPERATIONS AND OPTIONS

• Average Position Menu
• Estimated Accuracy -OK (usuallyltEPE)
• Measurement Count - OK (20 minimum)
• Scroll to (highlight) Save
• Press Enter

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III. UNIT OPERATIONS AND OPTIONS

• Mark Waypoint (Name)
• Six Character field
• Alpha / Numeric
• Scroll to top box
• Press Enter
• Use rocker keypad to enter name, press Enter

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III. UNIT OPERATIONS AND OPTIONS

• Mark Waypoint (Name)
• Comment field - 20 letters, numbers or symbols
• Scroll to Comment, Enter
• Use rocker keypad to enter description. Press
  Enter
• Scroll to Done. Press Enter to complete

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III. UNIT OPERATIONS AND OPTIONS

• Main Menu
• Scroll selections to Waypoints
• Enter to choose

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III. UNIT OPERATIONS AND OPTIONS

• Edit Waypoints
• Scroll to name or comment field
• Enter
• Keypad to edit
• Enter to complete
• Scroll to Done
• Enter

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III. UNIT OPERATIONS AND OPTIONS

• Delete Waypoints
• On Satellite Status Page
• Press Menu twice
• Waypoints is highlighted
• Press Enter
• Scroll to the Waypoint to be deleted
• Press Enter

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IV. WAYPOINT DATA COLLECTION

• LAND COVER CODES 
• DEC Forest Deciduous
• EVE Forest Evergreen
• HAG Herbaceous Agricultural
• NAG Herbaceous Non-Agricultural
• IMP Impervious
• BAR Bare Ground
•  

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IV. WAYPOINT DATA COLLECTION

• Definitions
• Forest - at least 75 of the area contains
  deciduous (DEC) or evergreen (EVE) trees of any
  height
• Herbaceous - Agricultural (HAG) - land surface
  consists of pasture land, crop land or other
  cultivated land
• Herbaceous - Non Agricultural (NAG) - land
  surface consists of lawn, golf course, athletic
  field (natural) or similar cover
• Impervious (IMP) - a black-topped or concrete
  surface, such as a parking lot
• Bare Ground (BAR) - Large bare ground areas
  including quarries and strip mines

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IV. WAYPOINT DATA COLLECTION

• Approach
• Select land cover areas at least one quarter acre
  in size, one acre preferred, (43, 560 square
  feet)
• Spread observations geographically throughout
  region

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IV. WAYPOINT DATA COLLECTION

• Observation Rules
• Each school shall number all observations
  sequentially, beginning with 001 through 999.
• All must use designated prefixes (codes) to
  identify different land cover types.
• EVE and DEC codes must have a minimum of 3
  sequential points to define a forest polygon.
  These points must follow each other either in a
  clockwise or counterclockwise direction around
  the perimeter of the polygon.
• All must insert at least one other type of land
  cover observation between forest polygon
  sequences.
• Forest polygons are needed due to potential
  multipath errors associated with GPS observations
  under tree canopy.

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IV. WAYPOINT DATA COLLECTION

• What the forest polygon should look like on the
  ground
• 1 acre 43,560 Square Feet
• 209 FT x 209FT
• ¼ Acre 10,890 Square Feet
• 53 FT x 53FT

209 Feet
209 Feet
53 Feet
53 Feet
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IV. WAYPOINT DATA COLLECTION

• Polygons in a large forest area
• Double the size of the area to account for GPS
  error

GPS Error inside of forest
418 Feet
Forest Edge
GPS Error outside of forest
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IV. WAYPOINT DATA COLLECTION
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IV. WAYPOINT DATA COLLECTION
Ground Truth Points

• IMP 001
• IMP 002
• IMP 003
• NAG 004
• NAG 005
• DEC 006
• DEC 007
• DEC 008
• DEC 009
• DEC 010

DEC 006
DEC 007
DEC 010
IMP 003
DEC 009
DEC 008
IMP 002
IMP 001
NAG 005
We are here
NAG 004
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V. WAYPOINT DATA REPORTING
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V. WAYPOINT DATA REPORTING
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V. WAYPOINT DATA REPORTING
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V. WAYPOINT DATA REPORTING
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V. WAYPOINT DATA REPORTING
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V. WAYPOINT DATA REPORTING