1. Global Positioning System (GPS) Allen Zhao, Guanlun He, Matt Cui

2. Agenda History How the Technology Works Other uses GPS Versions Available devices Indoor Positioning System 2

3. History Created by American Department of Defense in the 1960s during the Cold War Opened to the public in 1990 GPS released to public after a Korean commercial plane shot down due to accidentally venturing into Russian airspace 3 http://www.big-lies.org/NUKE- LIES/www.insidegnss.com/auto/popupimage/GPS%20IIF- assembly-Flag.jpg

4. 24 operational GPS satellites revolve around the earth Each travel along one of 6 orbits Orbits are created strategically Each point on earth needs at least 4 satellites pointing at you Your receiver only needs 3 - trilateration One is used as an auxiliary How it works https://upload.wikimedia.org/wikipedia/commons/9/9c/Co nstellationGPS.gif 4

5. Satellite A says “You are 50,000 km away from me” Trilateration 5 http://moorefarmsbg.org/wp- content/uploads/2014/05/GPS_3D- trilateration.png

6. Satellite A says “You are 50,000 km away from me” Satellite B says “You are 62,300 km away from me” Satellite C says “You are 40,800 km away from me” Trilateration 6 https://www.e- education.psu.edu/natureofgeoinfo/sites/www.e- education.psu.edu.natureofgeoinfo/files/image/gps_r anging_3.jpg http://farm3.static.flickr.com/2656/3728939543_15aaefe 316_o.jpg

7. Satellite A says “You are 50,000 km away from me” Satellite B says “You are 62,300 km away from me” Satellite C says “You are 40,800 km away from me” Satellite D can be used to get altitude coordinate Though, normally GPS devices will use the surface of the earth (You probably won’t be using Google Maps if you’re you’re floating in space) Trilateration 7 https://www.e- education.psu.edu/natureofgeoinfo/sites/www.e- education.psu.edu.natureofgeoinfo/files/image/gps_r anging_3.jpg http://farm3.static.flickr.com/2656/3728939543_15aaefe 316_o.jpg

8. GPS system receives signal from satellites and times how long it took for the signal to arrive this gives distance Need a very precise timing mechanism Take into account special and general relativistic factors All GPS satellites all have a very precise atomic clock Receiver also needs to know precise time Has a quartz oscillator that constantly syncs with the satellites time Trilateration 8 http://moorefarmsbg.org/wp- content/uploads/2014/05/GPS_3D- trilateration.png

9. Because of their very precise timing, GPS timers are used by time-sensitive systems Stock market Hollywood studios (time audio and video data & multi-camera sequencing) GPS timers Other Uses 9

10. GPS Satellites Types Type IIA (discontinued) One of the earliest GPS systems available to the public Recently discontinued this year Two distinct encoding types: Precise code and Coarse/Acquisition code Type IIF (current) Was designed to replace the IIA satellite First ones to have precise atomic clocks 20 feet accuracy New military (M) code that has enhanced security Type III (2017) Accurate to an arms length Stronger signal, longer life span 10

11. GPS Modules - EECS 373 Application https://www.sparkfun.com/products/1374 0 11 Around $20 - $50 Wide range of capabilities depending on the module. Many have flash memory for data logging applications. Couple require high range antenna to get a better signal. Relays information including but not limited to position, velocity, and time. https://www.sparkfun.com/products/11058

12. How to use them 12 Most communicate in some form of serial communication. Majority uses rs232/ uart, a couple use SPI and I2C Very easy to use with high level microcontrollers like Arduinos and Raspberry Pis

13. 13 $GPRMC Time Latitude, [N/S] Longitude, [E/W] Speed in knots Track Angle Date Magnetic variation Checksum Sample GPS packet $GPRMC,194530.000,A,3051.8007,N,10035.9 989,W,1.49,111.67,310714,,,A*74 http://www.doctormonk.com/2012/05/sparkfun- venus-gps-and-arduino.html

14. 14 #include SoftwareSerial gpsSerial(10, 11); // RX, TX (TX not used) const int sentenceSize = 80; char sentence[sentenceSize]; void setup(){ Serial.begin(9600); gpsSerial.begin(9600); } void loop(){ static int i = 0; if (gpsSerial.available()){ char ch = gpsSerial.read(); if (ch != '\n' && i < sentenceSize){ sentence[i] = ch; i++; } else{ sentence[i] = '\0'; i = 0; displayGPS(); }

15. IPS - Indoor Positioning System GPS does not work well inside buildings because the signal struggles to move through solid objects. Interference can corrupt the signal There is no standard for IPS but there are many commercial systems IPS does not use satellites, but instead can be implemented several ways including magnetic positioning, light, and measuring the distance to nearby nodes 15

16. Magnetic Positioning Magnetic Positioning uses a compass like technology to analyze the magnetic field produced by the earth and how it interacts with the steel and other materials in a building 16

17. Commercial IPS products http://www.wifarer.com/ (mobile app) uses Wifi Nodes http://www.wifarer.com/ http://www.locata.com/ Uses a module to create a beacon, simillar to GPS http://www.locata.com/ https://www.indooratlas.com/ Uses Magnetic Fields https://www.indooratlas.com/ ByteLyte Uses LED Lighting 17

18. 18 Questions?

19. https://en.wikipedia.org/wiki/Global_Positioning_System https://en.wikipedia.org/wiki/GPS_signals https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System http://www.gps.gov/systems/gps/space/ http://www.nasa.gov/directorates/heo/scan/communications/policy/GPS_History.html http://www.trimble.com/gps_tutorial/howgps.aspx http://electronics.howstuffworks.com/10-unconventional-uses-gps.htm https://www.sparkfun.com/categories/17 http://www.doctormonk.com/2012_05_01_archive.html https://en.wikipedia.org/wiki/Indoor_positioning_system Works Cited 19