Global Positioning System

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Global Positioning System

• Applications in Agriculture

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INTRODUCTION

• Agriculture is a changing industry. As
  technology makes agriculture more efficient,
  these systems have become commonplace in our
  industry. The goal of the Global Positioning
  System Applications in Agriculture instructional
  materials is to introduce precision agriculture
  into the Agricultural Education curriculum.

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• General instruction of Global Positioning Systems
  will be presented, as well as technical
  information and hands on applications on using
  the Garmin III and Garmin 12 handheld units. It
  is our hope that this curriculum will give both
  instructors and students a comprehensive
  understanding of Global Positioning Systems,
  regardless of the make and model of equipment
  that is available.

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• Global Positioning System Applications in
  Agriculture was prepared by Paul Oehlke,
  Agriculture Department Chair and instructor at
  the North Dakota State College of Science, and
  Tony Boehm, Agricultural Education instructor at
  the Richland County Vocational Center. This
  project was made possible by a United State
  Department of Agriculture grant received by NDSCS
  and RCVT, titled Implementing Precision
  Agriculture into the NDSCS and RCVT curriculums.

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Unit 1 Introduction to Global Positioning
Systems
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I What is GPS

• 1 Global Positioning Systems a network of
  satellites that makes it possible to precisely
  identify a location on earth
• 2 U.S. Dept. of Defense satellites transmit
  signals while orbiting the Earth in a precise
  pattern

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• 3 System comprised of
• a - at least 24 satellites
• 1 in a distinct pattern
• 2 approximately 12,000 miles above the earth
• 3 contain atomic clocks accurate to 1 second of
  error every 1 million years

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• b - ground control stations
• 1 uplinks corrected orbital and clock
  information
• 2 5 stations worldwide
• c receivers
• 1 handheld GPS receivers
• 2 mounted on farm implements, vehicles, planes,
  boats, ect

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II How does GPS work

• 1 Each satellite sends a data message to the
  receiver including
• a satellite location
• b clock corrections
• c rough information about other satellites in
  the constellation

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• 2 The time it takes the signal to reach the
  receiver allows the receiver to calculate the
  distance to the satellite
• 3 Using 3 satellites, latitude and longitude
  can be identified

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• 4 Altitude can be identified with a fourth
  satellite
• 5 Differential GPS (DGPS) uses known beacon
  locations to correct satellite within inches

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III History

• 1 The U.S. Dept. of Defense (DOD) designed and
  implemented the system for military applications
• 2 This system was referred to as NAVSTAR, or
  the Navigation Satellite Timing and Ranging by
  the DOD
• 3 The first satellite was launched in 1978

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• 4 A full constellation of 24 satellites was
  completed in 1994
• 5 GPS was to become available to civilians by
  an executive decree in the 1980s and in May 1,
  2000 GPS became fully available when the
  Selective Availability, or intentional clock
  noise, was turned off

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IV Uses and Careers

• 1 Engineering
• a city planning
• b city information systems
• c construction site restoration

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• 2 Military
• a troop deployment
• b navigation
• c artillery fire

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• 3 Outdoor Recreation
• a hiking and camping
• b finding specific recreation location

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• 4 Automotive/Aviation
• a navigate to specific location
• b identify location if lost, stolen, or in need
  of repair
• c locate and track fleet vehicles

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• 5 Agriculture
• a Field Guidance
• 1 reduce skips and overlap
• 2 mark locations
• a insect and weed infestations
• b low yield
• c soil characteristics

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• 3 create and follow accurate rows
• 4 advantages over foam
• a drive 20 faster with light bar in cab than
  foam 30 feet away
• b can be seen at night
• c foams can freeze
• 5 custom application of correct locations
• 6 variable rate application of fertilizers and
  seed

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• b Field Information Management
• 1 measure acreage accurately
• 2 keep records
• a yield
• b application rates
• c infestations
• 3 map fields for drainage
• 4 create topographical maps for variable rate
  application

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V Terminology

• 1 Control segment - A world-wide network of GPS
  monitor and control stations that ensure the
  accuracy of satellite positions and their clocks
• 2 Atomic Clock - A very precise clock that
  operates using the elements cesium or rubidium
  with an error of one second per million years
  GPS satellites contain multiple atomic clocks

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• 3 Beacon Land based transmitter that emits
  signals in all directions, broadcasting
  correction data to nearby GPS receivers for
  greater accuracy
• 4 Differential GPS (DGPS) - GPS system that
  uses beacons to correct GPS receivers DGPS
  reduces the effect of selective availability,
  weather, buildings, etc. and can improve position
  accuracy to within feet

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• 5 Waypoints - Locations or landmarks worth
  recording and storing in your GPS
• 6 Bearing - The compass direction to a waypoint
  measured to the nearest degree also call an
  azimuth
• 7 Track (TRK) - Your current direction of
  travel relative to a ground position Course Over
  Ground

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• 8 Coordinate - A set of latitude/longitude
  numbers that describes your location on or above
  the earth
• 9 Prime Meridian - The zero meridian, used as a
  reference line from which longitude east and west
  is measured runs from the north to south pole
  and passes through Greenwich, England

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• 10 Greenwich Mean Time (GMT)- The mean solar
  time for the meridian at Greenwich, England
  still the standard time zone for the prime
  meridian
• 11 Coordinated Universal Time (UTC) - Replaced
  GMT as the world standard for time in 1986 and is
  based on atomic measurements rather than the
  rotation of the earth

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• 12 Latitude - A position's distance north or
  south of the equator measured by degrees from
  zero to 90 one minute of latitude equals one
  nautical mile
• 13 Longitude - The distance east or west of the
  prime meridian

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• 14 Nautical Mile - Used in sea and air
  navigation and based on the length of one minute
  of latitude/longitude equal to 1,852 meters
  (about 6,076 feet)
• 15 Statute Mile Equal to 5,280 feet or 1,760
  yards (1,609 meters)

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• 16 Triangulation - A method of determining the
  location of an unknown point by using the laws of
  plane trigonometry
• 17 Dilution of Precision (DOP) - A measure of
  the GPS receiver-satellite geometry a low DOP
  value indicates better relative geometry and
  correspondingly higher accuracy

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• 18 Geographic Information Systems (GIS) - A
  computer system or software capable of
  assembling, storing, manipulating and displaying
  location information
• 19 Magnetic North - Represents the direction of
  the north magnetic pole from the observers
  position, or the direction a compass points may
  not be accurate

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• 20 True North - The true direction of the north
  pole
• 21 2D Operating Mode - A two-dimensional GPS
  position fix that includes only horizontal
  coordinates requires a minimum of three visible
  satellites

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• 22 3D Operating Mode - A three-dimensional GPS
  position fix that includes horizontal and
  elevation coordinates requires a minimum of four
  visible satellites
• 23 Wide Area Augmentation System (WAAS) a
  DGPS system used by the Federal Aviation
  Administration

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 Unit 2 - How to Use the Garmin III