GPS: Global Positioning GPS: Global Positioning SystemSystem

April 19, 2023April 19, 2023

Global Positioning SystemsGlobal Positioning Systems

• GPS is a revolutionary GPS is a revolutionary navigation systemnavigation system– 24 satellites orbiting the 24 satellites orbiting the

earthearth– Provide location within Provide location within

metres or less anywhere on metres or less anywhere on the globe.the globe.

– Now available in many cars Now available in many cars as an optionas an option

– Created and operated by Created and operated by the US Department of the US Department of DefenseDefense

More about GPS satellitesMore about GPS satellites

• Constellation of 27 satellitesConstellation of 27 satellites– (24 active + 3 spare)(24 active + 3 spare)

• Orbit 12,600 miles above earthOrbit 12,600 miles above earth– (10,900 nautical miles)(10,900 nautical miles)

• Satellites in 12 hour orbitSatellites in 12 hour orbit• First satellite launched in 1978, 24First satellite launched in 1978, 24 thth became became

operational in 1994operational in 1994• Selective availability was removed in May, Selective availability was removed in May,

20002000– Handheld receivers are now much more accurateHandheld receivers are now much more accurate

How does GPS work?How does GPS work?

• Measuring distance by measuring timeMeasuring distance by measuring time

– Satellites send coded signals indicating Satellites send coded signals indicating their position in space and the exact time their position in space and the exact time the signals are being sent the signals are being sent

– Receivers use the time it takes signal to Receivers use the time it takes signal to travel from satellite to receiver to determine travel from satellite to receiver to determine distance from satellite to receiverdistance from satellite to receiver

– Information from multiple satellites is used Information from multiple satellites is used to determine position through ‘triangulation’to determine position through ‘triangulation’

How does GPS work?How does GPS work?

More about GPS receiversMore about GPS receivers

• A GPS receiver's job is to locate A GPS receiver's job is to locate four or more satellites, figure out four or more satellites, figure out the distance to each, and use this the distance to each, and use this information to deduce its own information to deduce its own location. location. – Hand-held receivers for recreational Hand-held receivers for recreational

use with accuracy of 10-15 metresuse with accuracy of 10-15 metres– Vehicle mounted receivers for Vehicle mounted receivers for

navigation or agricultural use with navigation or agricultural use with accuracy of < 1 metreaccuracy of < 1 metre

– Backpack or tripod mounted Backpack or tripod mounted receivers for surveying use with receivers for surveying use with accuracy of 5 – 10 centimetresaccuracy of 5 – 10 centimetres

More about GPS receiversMore about GPS receivers

• Receivers require clear line-of-sight; thus, Receivers require clear line-of-sight; thus, they will not work indoors or where tall objects they will not work indoors or where tall objects obscure the skyobscure the sky

What’s so cool about GPS?What’s so cool about GPS?

• GPS unitsGPS units– Can be used as a digital compassCan be used as a digital compass– Can be used to determine ground speedCan be used to determine ground speed– Can store landmarks (locations)Can store landmarks (locations)– Can be used for dynamic routingCan be used for dynamic routing– Can be used for mapping applicationsCan be used for mapping applications

Applications of GPSApplications of GPS

• In-vehicle Navigation (car, boat, airplane)In-vehicle Navigation (car, boat, airplane)• Asset ManagementAsset Management• ConstructionConstruction• Geologic Research & MiningGeologic Research & Mining• Military Navigation and OperationsMilitary Navigation and Operations• Mapping & SurveyingMapping & Surveying• Precision AgriculturePrecision Agriculture• Public Health Public Health • Public SafetyPublic Safety• Wireless CommunicationsWireless Communications

GPS in the classroomGPS in the classroom

E C Drury Scavenger HuntE C Drury Scavenger Hunt

Integrating GIS and GPSIntegrating GIS and GPS

• Collect a series of latitude and longitude Collect a series of latitude and longitude points using GPS receiverspoints using GPS receivers– add them into an existing digital map add them into an existing digital map

• Skills in Skills in – data collection/creationdata collection/creation– GPS readingGPS reading– observationobservation

• Digital photosDigital photos

GeocachingGeocaching

• A great way to introduce students to GPSA great way to introduce students to GPS– Teach latitude/longitudeTeach latitude/longitude– Take advantage of the wonderful features and Take advantage of the wonderful features and

capability of your GPS unitcapability of your GPS unit

• An entertaining adventure for GPS usersAn entertaining adventure for GPS users– Individuals and organizations all over the world Individuals and organizations all over the world

have set up caches and shared the locations of have set up caches and shared the locations of these caches on the Internetthese caches on the Internet

– Participate in a cache hunt to find an existing Participate in a cache hunt to find an existing cache or create your owncache or create your own

• www.geocaching.comwww.geocaching.com

Classroom projectsClassroom projects

• There are many ways you can incorporate There are many ways you can incorporate GPS data collection into your classroomGPS data collection into your classroom

• Possibilities includePossibilities include– a virtual trail in your areaa virtual trail in your area– mapping the locations of litter and garbage cans to mapping the locations of litter and garbage cans to

determine if there is a relationship, and if more determine if there is a relationship, and if more garbage cans are necessarygarbage cans are necessary

– collecting data about tree types and locations on collecting data about tree types and locations on school grounds and beyondschool grounds and beyond

– gathering water samples from a local stream and gathering water samples from a local stream and taking GPS readings at each locationtaking GPS readings at each location

– orienteering/navigating (hiking, boating, biking, orienteering/navigating (hiking, boating, biking, driving)driving)

Getting startedGetting started

• GPS units - Garmin eTrexGPS units - Garmin eTrex– perfect for introducing students to field perfect for introducing students to field

data collection and the power of GPSdata collection and the power of GPS– industry's smallest and lightest industry's smallest and lightest

handheld GPS receiverhandheld GPS receiver– sleek waterproof housing will fit in sleek waterproof housing will fit in

your shirt pocket and weighs only 5.3 your shirt pocket and weighs only 5.3 ouncesounces

– a 12 channel parallel receiver, a 12 channel parallel receiver, differential ready, with a built-in patch differential ready, with a built-in patch antennaantenna

– runs for 22 hours on just two AA runs for 22 hours on just two AA batteriesbatteries

• Pencil, clipboard, paperPencil, clipboard, paper

Getting started - additionsGetting started - additions

• Connection cables for your GPS unitsConnection cables for your GPS units– Allow you to download data from your GPS unit to Allow you to download data from your GPS unit to

your computeryour computer– Free extension available to convert to shapefileFree extension available to convert to shapefile

• Local dataLocal data– Create a base map for viewing the data you have Create a base map for viewing the data you have

collectedcollected– Provides context and other features for GIS Provides context and other features for GIS

analysis with ArcViewanalysis with ArcView

• Digital cameraDigital camera

Collecting dataCollecting data

• Collect data in the field using GPSCollect data in the field using GPS– Write down point coordinates and Write down point coordinates and

additional data observationsadditional data observations- OR - - OR -

– Use tracking function of your unit to store Use tracking function of your unit to store points, lines, or polygons, and write down points, lines, or polygons, and write down additional observationsadditional observations

Using the data you collectUsing the data you collect

• Manually enter the coordinates and Manually enter the coordinates and observations into a table (Excel, etc.)observations into a table (Excel, etc.)– Save as a .dbf fileSave as a .dbf file– Add to ArcViewAdd to ArcView– Use “Add X,Y” or “Add Event Theme” to Use “Add X,Y” or “Add Event Theme” to

create points on your mapcreate points on your map - OR - - OR -

• Use your GPS unit cable to download Use your GPS unit cable to download the data from the unit to your computerthe data from the unit to your computer

For more information…For more information…

• Books from ESRI PressBooks from ESRI Press– Integrating GIS and the Global Positioning Integrating GIS and the Global Positioning

SystemSystem• Karen Steede-TerryKaren Steede-Terry

– Fun with GPSFun with GPS• Donald CookeDonald Cooke

– Community Geography: GIS in ActionCommunity Geography: GIS in Action• Kim Zanelli English and Laura S. FeasterKim Zanelli English and Laura S. Feaster

For more information…For more information…

• Lessons on the ESRI Canada websiteLessons on the ESRI Canada website– http://k12.esricanada.comhttp://k12.esricanada.com– Integrating GIS and GPS (ArcView 3.x)Integrating GIS and GPS (ArcView 3.x)– Exploring Pukaskwa National Park Exploring Pukaskwa National Park

(ArcView 8.x/9.x)(ArcView 8.x/9.x)• Garmin websiteGarmin website

– http://www.garmin.com/http://www.garmin.com/• Trimble GPSTrimble GPS

– www.trimble.com/gpswww.trimble.com/gps• How stuff worksHow stuff works

– www.howstuffworks.comwww.howstuffworks.com