1. USE OF GPS METHODOLOGY IN CELLPHONE Submitted to Dr. Ahmed El-Rabbany Professor of Geometrics Engineering Department of Civil Engineering Ryerson University Submitted by: Atique Ahmed ID # 989056528 Images courtesy of USDoD and writer

3. OVERVIEW GPS OPERATIONS What does GPS ? GPS was originally intended for military applications, but in the 1980s, the US DoD made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day. There are three Satellite Navigation systems; GPS, GLONASS and GALILEO. I would reflect GPS only. GPS was developed in the 1970s GPS is satellite navigation system used to know specific location and time almost anywhere on the globe.

6. HOW RECEIVERS WORK? The GPS receiver and satellite generate the same pseudo-random code at exactly the same time. When the code arrives from the satellite, the time difference is compared to the same code generated by the receiver. This difference is multiplied by the speed of light 299,729,458 m/s (186,000 miles per second) to determine the distance to the satellite. (Note: Considering there is no GPS errors or biases interface)

7. HOW RECEIVERS WORK?.... Pseudo-random code generated by receiver Pseudo-random code generated by satellite Time difference Image courtesy to Nokia website

8. CALCULATION METHODOLGY Let suppose a driver travels from Toronto to Niagara Fall city, triangulation is a trigonometry function helps us to find the distance to a destination point using known angle and sides of a triangle. Measures distance using law of Cosine 20100 ? Calculate the distance from A to B ( C ) using Law of Cosine 19 0 20000 Suppose a satellite (S ) is from 20100 KM away from a point A (Toronto) and 20000 KM from point B (Niagara Fall City). B = Niagara falls A = Toronto S = Satellite

9. CALCULATION METHODOLGY By inserting the values in equation we find that C2 is equal to (20000)2 + (20100)2 – 2(20000)(20100) Cos(19deg). Measures distance using law of Cosine As Cellphone receiver does not measure angles, but they calculate the time in which signal took to reach Cellphone receiver. By simplifying, we calculated C 2 is equal about 1,000KM or C = 100KM This example helps us how to GPS on Cellphone determine the distance from one point to destination point.

10. USE OF TRILATERATION Trilateration is the method using measured distance from three satellites to cell phone receiver. When the distances from three different satellites are obtained in Cellphone receiver then using trilateration method, position of the receiver can be measured. HOW GPS RECEIVER WORKS?

11. Using Trilateration Mythology Intersection Point Providing location HOW GPS RECEIVER WORKS?

12. Understanding Errors and Biases Light Refraction: Sometimes the GPS signal from the satellite doesn’t follow a straight line. Refraction is the bending of light as it travels through one media to another. HOW GPS RECEIVER WORKS?

13. Differential Correction Differential correction is a technique that greatly increases the accuracy of the cellular collected GPS data. It involves correlation of Cell Phone receiver with base station - like Fido, Bell, or TELUS. Satellite signals use L1 and L2 to communicate with cellular while Base Stations use CDMA - Code Division Multiple Access at 1900 MHz. CELL PHONE METHODOLOGY USING GPS

14. Differential GPS System Photo courtesy to Google Base Station-Tower CELL PHONE USING GPS…. Differential Global Positioning System (DGPS) is an improvement to Global Positioning System data received by cellular receiver. The Cellular Receiver correct their pseudoranges by synchronizing with base stations. The correction signal is typically broadcast over UHF radio modem.

15. Differential Correction Cell phones & Service Provider: User + Service Provider + Satellite Link Images courtesy to Clip Art & iPhone CELL PHONE USING GPS….

16. 4G Cell phones converts RF to digital signals User + Service Provider + Satellite Link Digital Signals Service Provider Processor RF Images courtesy to clip art & iPhone CELL PHONE USING GPS….

17. Cellular system is very attractive to use in: 911 For emergency calls AVL Automatic Vehicle Location RTK GPS Real Time Kinematic Real Time Kinematic (RTK) is a technique used to measure carrier phase for GPS satellite navigation. GPS and Cellular Integration FEATURES OF CELL PHONE USING GPS

19. CONCLUSION A reference station (base station and tower) calculates differential corrections for its own location and time. Phones would remain in contact with their respective base stations up to 370 km (200 miles) from the station. However, some atmospheric errors and biases vary this space: specifically, satellite ephemeris errors and those introduced by ionospheric and tropospheric distortions. For this reason, the accuracy of DGPS may decreases with distance from the reference station.

20. Case Study How does iPhone work with GPS Developer: Apple Inc. Manufacturer: Foxcom & Pegatron Model 3G or 4G Built in GPS Receiver CDMA Mode enable UMTS/OSM enable Network 2.4 GHz at 802.11 b/g/n GPS enable with A-GPS support Simcard: MicroSIM card support CPU – A4 (ARM cortex-A8) dual core RAM 512 KB Storage memory: 8-32 GB Frequency response: 20Hz to 20KHz Power Li-ion battery 3.7V Software iOS 4.3.1 CDMA Application: Google Maps and Digital compass

21. Useful Acronyms using iPhone CDMA = Code Division Multiple Access UMTS = Universal Mobile Telecommunication System (Terrestrial Radio Access Network) GSM = Global System for Mobile-communication iOS = iPhone Operating System CPU = Central Processing Unit (ARM-Cortex – A8) RAM = Random Access Memory

23. Questions? Thanks for Your Attention