GPSTHE GLOBAL POSITIONING

SYSTEM

GPSIt’s in cars, boats, planes, tractors, golf carts, cell

phones, shoes

What is GPS?

GPS technology has matured into a resource that goes far beyond its original design goals. These days scientists, sportsmen, farmers, soldiers, pilots, surveyors, hikers, delivery drivers, sailors, dispatchers, lumberjacks, fire-fighters, and people from many other walks of life are using GPS in ways that make their work more productive, safer, and sometimes easier.

These applications fall into five broad categories:

Location - determining a basic position Navigation - getting from one location to another Tracking - monitoring the movement of people and things Mapping - creating maps of the world Timing - bringing precise timing to the world

What is GPS? GPS is a satellite-based radio

navigation system that allows anyone anywhere on the planet to determine their 3D position with great accuracy and precision.

Because there are still security issues (this was created by the DOD) there are places where signals don’t always pick up with high precision.

The system does undergo uprades periodically so signals may not be accurate “forever”

– DOD - NAVSTAR– Russia -GLONASS– EEC - Under development

Who maintains GPS?

The system is composed of three segments– Space - The orbiting satellites

– Control - The monitoring stations on earth– User - The GPS units such as you will use today.

The System kind-of “In Action”

A NAVSTAR satellite. •Life expectancy of about 10 years….new ones are being put in to orbit annually. •They are approx. 11,000 miles above the earth.•Each one weighs about 2,000 pounds and span about 17 feet across.•They are powered by solar panels

The system is composed of three segments– Space - The orbiting satellites– Control - The monitoring stations on earth

Our Model – The eTrex Legend from Garmin

The GPS pre-test: When was GPS first used?

–Sputnik…1957–TRANSIT…1960’s–NAVSTAR…1970’s

– 27 at the current time – 24 to maintain a system

How many satellites make up a GPS?

Your GPS receiver must track at least 3 satellites to give you an accurate position

location. 4 for an accurate elevation measurement.

From Circles to Waves

These two graphs both represent The NAVSTAR constellation of

satellites.

How would you describe the path of a single satellite in each graph? How would you explain the transition from one graph to the other?

– Government Military Agencies - Conservation, Weather, Rescue

– Industry Transportation Fishing Agriculture

– General Public Recreation Emergency / Security Reasons Health Related Reasons

Who uses GPS?

– Each GPS satellite transmits an accurate position and time signal.

– The user’s receiver measures the time delay for the signal to reach the receiver.

– Measurements collected from 4 satellites are processed to solve for the 3D position, velocity and time.

How does GPS Work?

Where on Earth are we?

Your Task Outside

1) Get a locked reading on your unit. 2) Chose a direction either east-west, or north-south.3) Walk along the direction vector until the reading on your unit changes.4) Design a method for finding the circumference of the earth based on your observations.

What you discovered outside.

1) Did you all get the exact same reading?2) How did you know your direction?3) How many paces until the reading on your unit changed?4) What was your method for finding the circumference of the earth?5) Would the circumference be the same for N/S as E/W?

A Sample LessonFrom:

Mission MathematicsA NASA/NCTM Project

How Does This Fit Into a Math Class?!

Pre Algebra: Latitude and Longitude, Integers Algebra I: Linear Systems, Absolute Value Geometry: Degree Measure, Circles, Spherical

Geometry Algebra II: Systems of Circles, 3D Graphing

How Does This Fit Into a Math Class?!

Trigonometry: Orbits as Sinusoids, Bearing, College Algebra: Conic Sections, 3D

Systems Pre Calculus: Accuracy, Precision, Error Calculus: Discrete Math: Circuits, Paths,

Triangulation

Available Materials The WEB:

Overview of GPS: http://www.utexas.edu/depts/grg/gcraft/notes/gps/gps.html U.S. Coast Guard: http://www.navcen.uscg.milInst. of Navigation: http://www.ion.orgGLONASS info: http://www.rssi.ru/SFCSIC/SFCSIC_main .htmlGPS sites: http://www.inmet.com/~pwt/gps_gen.htm "GPS for Fun": http://www.gps4fun.com SpatialTek: http://www.mapfacts.com/gps/history.aspCraig Haggart: http://vancouver~webpages.com/peter/gpswork.txtTrimble: http://www.trimble.com/gps/Science Junction: http://www.ncsu.edu/science junctionLesson Plans: http://wwwedu.ssc.nasa.gov/Itp/LessonPlans/