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FOT 2213 Applications of GPS/GIS in Forestry

Prepared by the Eddie L. Moore

Itawamba Community College

Global Positioning System

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Where on Earth am I?Where on Earth am I?Have you ever asked yourself this question

when you were in unfamiliar surroundings?

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Technology to the Technology to the RescueRescue

One of the most exciting technologies to evolve in the past decade is now available practically to everyone.

More and more people and businesses are using this technology for a variety of applications.

What is this technology called?

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G P SG P S Global

Positioning

System

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What is GPS?What is GPS? GPS is a satellite navigation system that

allows a properly equipped user to determine his or her exact position on the earth anytime, in any weather, and in most any location.

The GPS satellites are operated and maintained by the United States Department of Defense.

NAVSTAR is the official U.S. Department of Defense name for GPS.

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GPS –A New ConstellationGPS –A New Constellation GPS is the most significant recent advance in

navigation and positioning technology. In the past, the stars were used for navigation. Today's world requires greater accuracy.  The new constellation of artificial stars provided by the GPS serves this important need.

GPS is an aerospace technology that uses satellites and ground equipment to determine position anywhere on Earth.  Anyone with a small receiver can use the system at no cost.  GPS has drastically changed methods of navigation and is fast becoming important in everyday life.

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The GPS RevolutionThe GPS Revolution During the 1960s the military worked on a

number of navigation systems for a variety of applications.

In 1973 the Department of Defense directed the services to unify their systems.

The basis for the new system would be atomic clocks carried on satellites.

The Air Force would operate the new system called the Navstar Global Positioning System.

It has since become known simply as GPS.

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GPS Goes PublicGPS Goes Public GPS was designed so that civilian users could

not obtain the same accuracy that the military could. Nevertheless, civilian use was also intended from the start.

In 1983, President Ronald Reagan issued a directive that guaranteed GPS signals would be available at no charge to the world.

That directive helped open up a commercial market.

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GPS Public AwarenessGPS Public Awareness Deployment of GPS continued at a steady pace

through the 1990s. GPS burst into public awareness during the

Persian Gulf War in 1991. GPS was used extensively during that conflict, so

much so that not enough military-equipped GPS receivers were available.

To satisfy demand, the Department of Defense acquired civilian GPS units and temporarily changed GPS transmissions to give civilian receivers access to higher-accuracy military signals.

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GPS History and FactsGPS History and Facts First satellite launched in 1978.

Initial operational capability Dec. 8, 1993

Full constellation of 24 satellites was achieved in 1994. Fully operational April 27, 1995.

Each satellite is built to last about 10 years.

Transmitter power is only 50 watts or less.

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Advantages of GPSAdvantages of GPS

Operates in all weather.Operates in all weather.

Available 24 hours a day.Available 24 hours a day.

Available anywhere on earth. Available anywhere on earth.

No subscription or set-up fees.No subscription or set-up fees.

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Who Uses GPS?Who Uses GPS?GPS has a variety of applications on land,

at sea and in the air.GPS allows you to record or create

locations for places on the earth and help you navigate to and from those spots.

Airborne applications include navigation by private and commercial aircraft.

On the water, GPS is used for navigation by boaters and fishing enthusiasts.

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Land Based ApplicationsLand Based Applications GPS has become popular with hunters, hikers,

bikers, cross-country skiers, etc. Delivery trucks can receive GPS signals and

instantly transmit their position to a central dispatcher.

Police and emergency services use GPS to dispatch vehicles with reduced response time.

Foresters and surveyors use GPS for an ever increasing portion of their work.

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GPS in EducationGPS in EducationGPS Technology is becoming more widely use

in a variety of educational programs.The latest editions of Forestry, Surveying,

Geography and other textbooks have added sections and/or chapters devoted to GPS Technology and related applications.

GPS courses of study have been added to program curriculum.

GPS textbooks are being published.

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GPS SegmentsGPS SegmentsThe Global Positioning System is

made up of three segments:

Space SegmentSpace Segment

Control SegmentControl Segment

User SegmentUser Segment

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Space SegmentSpace SegmentConsists of the GPS satellites (space vehicles) which send radio signals from space. The GPS constellation consists of 24

satellites that orbit the earth in 12 hours. There are six orbital planes with four satellites

in each plane. The constellation provides the user with 5 to 8

visible satellites from any point on earth. The satellites send orbital data to GPS

receivers via radio signals.

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Space SegmentSpace Segment

Satellite

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Control SegmentControl SegmentConsists of a system of tracking stations

located around the world. The Master Control facility is located at

Schriever (Falcon) Air Force Base in Colorado. These control stations monitor data from the

satellites to compute precise orbital data and clock corrections for each satellite.

The Master Control station uploads corrected orbital and clock data to the satellites.

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Control StationsControl Stations

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GPS ControlGPS Control

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User SegmentUser Segment

Consists of the GPS receivers and the user community.

GPS receivers convert satellite signals into position, velocity, and time estimates.

Four satellites are required to compute the four dimensions of X,Y, Z (position) and Time.

GPS receivers are used for navigation, positioning, and other research.

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GPS ReceiverGPS Receiver

A specialized electronic device

with the ability to determine the

user’s position on earth by

processing signals received from

satellites orbiting the earth.

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Some Available GPS Some Available GPS ReceiversReceivers

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How Does GPS Work?How Does GPS Work? Global Positioning System satellites transmit signals to

equipment on the ground. Each GPS satellite transmits data that indicates its

location and the current time. Distance from GPS receiver to the each satellite is

determined by estimating the amount of time it takes for the signal to reach the receiver.

When the receiver estimates the distance to at least four GPS satellites, it can calculate its position in three dimensions by a process known as trilateration.

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Determining PositionDetermining Position

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The GPS Receiver’s JobThe GPS Receiver’s Job

Locate 4 or more satellites.Locate 4 or more satellites.

Calculate the distance to each.Calculate the distance to each.

Use this information to determine Use this information to determine it’s own location. it’s own location.

This process is ‘This process is ‘TrilaterationTrilateration’.’.

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Indicating PositionIndicating PositionA GPS unit will normally indicate the A GPS unit will normally indicate the user’s 3D position using the World user’s 3D position using the World Geographic Grid and will indicate the Geographic Grid and will indicate the latitude, longitude and altitudelatitude, longitude and altitude (LLA).(LLA).

In addition to LLA many GPS units can In addition to LLA many GPS units can be setup to indicate the position in be setup to indicate the position in other grid systems including other grid systems including Universal Transverse Mercator (UTM) Universal Transverse Mercator (UTM) and State Plane Coordinates (SPC).and State Plane Coordinates (SPC).

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Accuracy of GPSAccuracy of GPS

GPS receivers are extremely GPS receivers are extremely accurate due to their parallel multi-accurate due to their parallel multi-channel design. channel design.

GPS receivers, on average, are GPS receivers, on average, are usually accurate to within 15 meters.usually accurate to within 15 meters.

GPS receivers equipped with the GPS receivers equipped with the Wide Area Augmentation System Wide Area Augmentation System (WAAS) can improve accuracy to (WAAS) can improve accuracy to within 3 meters on average.within 3 meters on average.

Differential GPS corrects GPS signals Differential GPS corrects GPS signals to an accuracy to an average of 3 to 5 to an accuracy to an average of 3 to 5 meters.meters.

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Sources of Position ErrorsSources of Position ErrorsAtmospheric signal delay.Atmospheric signal delay.

Signal multi-path.Signal multi-path.

Receiver clock errors.Receiver clock errors.

Orbital errors.Orbital errors.

Number of satellites visible.Number of satellites visible.

Satellite geometry.Satellite geometry.

Selective AvailabilitySelective Availability (this intentional (this intentional degradation of the satellite signal by the degradation of the satellite signal by the U.S. military was made inactive in May U.S. military was made inactive in May 2000).2000).

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Reduction of GPS Signal Reduction of GPS Signal ErrorsErrors

GPS data can be differentially corrected to GPS data can be differentially corrected to remove many of the errors and improve remove many of the errors and improve accuracy. These corrections can be done in accuracy. These corrections can be done in real time or by post processing on a computer real time or by post processing on a computer using PC GPS software. In both cases data in using PC GPS software. In both cases data in obtained from a GPS reference station at a obtained from a GPS reference station at a known location. Knowing the exact location known location. Knowing the exact location the reference station can determine the errors the reference station can determine the errors in the satellite signal. This error data is applied in the satellite signal. This error data is applied to the GPS receiver data to correct many of to the GPS receiver data to correct many of the errors and improve accuracy.the errors and improve accuracy.

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Satellite GeometrySatellite Geometry

The satellites continuously orbit the earth and therefore their orientation in relation to the GPS receiver in always changing.

Therefore, a major factor in determining GPS positional accuracy is the geometry (or spread) of the group of satellites (constellation) from which signals are being received.

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Dilution of Precision (DOP)Dilution of Precision (DOP)

The geometry of the constellation is evaluated for several factors, all of which fall into the category of Dilution of Precision or DOP.

DOP is an indicator of the quality of the geometry of the satellite constellation.

A lower DOP value indicates a better signal and accuracy.

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Satellite SpreadSatellite Spread

Good satellite geometry.

Greater angles/better spread between satellites.

Lowers the DOP and provides a better signal.

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Satellite SpreadSatellite Spread

Poor satellite geometry

Smaller angles/poorer spread between satellites.

Increased DOP and inferior measurement configuration.

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GPS Applications:GPS Applications:An Instructional TechnologyAn Instructional Technology

Forestry Agriculture Geography Surveying Environment Natural Resources

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GPS Forestry InstructionGPS Forestry Instruction

GPS units are is being used for instruction and GPS units are is being used for instruction and application in the following Forestry classes at application in the following Forestry classes at Itawamba Community College.Itawamba Community College.

Applications of GPS/GIS in ForestryApplications of GPS/GIS in Forestry

Forest Measurements IIForest Measurements II

Silviculture ISilviculture I

Timber HarvestingTimber Harvesting

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The Forestry classes at ICC use The Forestry classes at ICC use the Corvallis Microtechnology, the Corvallis Microtechnology,

Inc. Inc. March II EMarch II E GPS GPS

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GPS Forestry ApplicationsGPS Forestry Applications

The GPS units and PC-GPS software are used to The GPS units and PC-GPS software are used to collect and process data for a number of Forestry collect and process data for a number of Forestry applications including:applications including:

Navigation. Navigation.

Field acreage determination.Field acreage determination.

Road, boundary and geographic point layout.Road, boundary and geographic point layout.

Mapping tracts of timber and other land areas.Mapping tracts of timber and other land areas.

Georeferencing GPS data on aerial photos.Georeferencing GPS data on aerial photos.

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ICC Forestry Students ICC Forestry Students Receiving GPS InstructionReceiving GPS Instruction

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Instructor Collects GPS Field Instructor Collects GPS Field Data for Class ExercisesData for Class Exercises

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ICC Forestry Students ICC Forestry Students Preparing GPS Units for Data Preparing GPS Units for Data

CollectionCollection

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ICC Forestry Students collect GPS ICC Forestry Students collect GPS data to find acreage.data to find acreage.

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Students Comparing Collected Students Comparing Collected DataData

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GPS NavigationGPS Navigation

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I used GPS to get here so this I used GPS to get here so this must be the right place?must be the right place?

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Military Use of GPSMilitary Use of GPS

                                                            

      More than 9,000 GPS receivers were More than 9,000 GPS receivers were used by U.S. and coalition forces during used by U.S. and coalition forces during Operation Desert Storm.Operation Desert Storm.

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PROJECT 2005PROJECT 2005

CONGRESSIONAL MANDATECONGRESSIONAL MANDATE"LIMITATION ON PROCUREMENT OF SYSTEMS NOT GPS-"LIMITATION ON PROCUREMENT OF SYSTEMS NOT GPS-EQUIPPED:EQUIPPED:

After September 30, 2005, After September 30, 2005, funds may not be obligated funds may not be obligated to modify or procure any to modify or procure any Department of Defense Department of Defense aircraft, ship, armored aircraft, ship, armored vehicle, or indirect-fire vehicle, or indirect-fire weapon system that is not weapon system that is not equipped with a Global equipped with a Global Positioning System Positioning System receiver."receiver."

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Scientist uses GPS to Scientist uses GPS to collect data for collect data for

topographic survey.topographic survey.

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Land ManagementLand Management

GPS receivers installed in farm equipment provide accurate position information. This enables farmers to apply fertilizers and harvest crops with great precision.

GPS and Agriculture

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Land ManagementLand ManagementCrop Yield Map

Maps of crop yield can be made using agricultural GPS systems. The map shown here indicates how crop yield varies across a field. These maps can be created during harvesting, allowing farmers to accurately plan how the fields should be used and fertilized for future crops.

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GPS Navigation System GPS Navigation System in Automobilesin Automobiles

Find your way without asking directions. Find your way without asking directions. The GPS unit will show and tell you the way.The GPS unit will show and tell you the way.

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GPS Navigation System GPS Navigation System in Emergency Vehiclesin Emergency Vehicles

Faster DeploymentFaster Deployment

Quicker ResponseQuicker Response

Tracking of VehiclesTracking of Vehicles

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GPS Navigation System GPS Navigation System in Airplanesin Airplanes

Better air traffic control Better air traffic control

Easier navigationEasier navigation

Keep planes on courseKeep planes on course

Minimize effect of weatherMinimize effect of weather

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GPS Navigation System GPS Navigation System in Ships and Boatsin Ships and Boats

Easier navigation at seaEasier navigation at sea

Maintains set courseMaintains set course

Works in any weatherWorks in any weather

Works night or dayWorks night or day

Faster search and rescueFaster search and rescue

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Final ThoughtsFinal Thoughts

The future of GPS technology is The future of GPS technology is as unlimited as your imagination. as unlimited as your imagination. New applications will continue to New applications will continue to be created as the technology be created as the technology evolves. The GPS satellites, like evolves. The GPS satellites, like handmade stars in the sky, will be handmade stars in the sky, will be guiding you well into the 21st guiding you well into the 21st century. century.