1. Andrew McLean Kelvin Barraclough Gisborne Secondary College

2. What is GPS? 24 + satellites

3. What is GPS? 24 + satellites Several ground stations

4. What is GPS? 24 + satellites Several ground stations GPS receiver

5. Satellites Altitude ≈ 20200 km

6. Satellites Altitude ≈ 20200 km Period 12 hours

7. Satellites Altitude ≈ 20200 km Period 12 hours At least 4 visible everywhere

8. Satellites Altitude ≈ 20200 km Period 12 hours At least 4 visible everywhere Solar powered, ≈ 50 W transmitter

9. Satellites Altitude ≈ 20200 km Period 12 hours At least 4 visible everywhere Solar powered, ≈ 50 W transmitter Transmit on 1575.42 MHz

10. Satellites Altitude ≈ 20200 km Period 12 hours At least 4 visible everywhere Solar powered, ≈ 50 W transmitter Transmit on 1575.42 MHz Fitted with atomic clocks

11. Satellites Altitude ≈ 20200 km Period 12 hours At least 4 visible everywhere Solar powered, ≈ 50 W transmitter Transmit on 1575.42 MHz Fitted with atomic clocks Lifespan ≈ 10 years

12. Ground Stations I master station, four remote

13. Ground Stations I master station, four remote Monitor satellites and send back accurate orbital and time data

14. The Signal The “almanac”. Approximate position of all satellites, transmitted and stored in the GPS.

15. The Signal The “almanac”. Approximate position of all satellites, transmitted and stored in the GPS. The “ephemeris”. Accurate data of individual satellite position.

16. The Signal The “almanac”. Approximate position of all satellites, transmitted and stored in the GPS. The “ephemeris”. Accurate data of individual satellite position. The “pseudo random code”. Effectively, an accurate time signal

17. The Signal The “almanac”. Approximate position of all satellites, transmitted and stored in the GPS. The “ephemeris”. Accurate data of individual satellite position. The “pseudo random code”. Effectively, an accurate time signal Turned off while satellite orbit is adjusted

18. Satellite positions 27400 km 20200 km

19. Signal times 0.091 s 0.067 s

20. Establishing position

22. If receiver had a good enough clock – Two satellites – somewhere on a circle

23. Establishing position If receiver had a good enough clock – Two satellites – somewhere on a circle 3 rd satellite – cuts this circle twice, but usually one solution is obvious

24. Establishing position If receiver had a good enough clock – Two satellites – somewhere on a circle 3 rd satellite – cuts this circle twice, but usually one solution is obvious 4 th satellite – removes ambiguity

25. Establishing position With a small, cheap clock -

26. Establishing position With a small, cheap clock – 3 satellites give 2D fix

27. Establishing position With a small, cheap clock – 3 satellites give 2D fix 4 satellites give 3D fix

28. Accuracy Given clear view of sky typically 5 – 10 m

31. Receivers Aren’t equal

32. Receivers Aren’t equal Need “good view” of sky

33. Possible information Position

34. Possible information Position Distance travelled

35. Possible information Position Distance travelled Speed

36. Possible information Position Distance travelled Speed Direction

37. Possible information Position Distance travelled Speed Direction Altitude

38. Gathering data – “low tech”

42. Gathering data – “hi tech” Almost all GPS receivers can be connected to a computer to transfer data

43. Suitable software (1) “OziExplorer”

44. Suitable software (1) “OziExplorer” $130

45. Suitable software (1) “OziExplorer” $130 Uses raster mapping

46. Suitable software (1) “OziExplorer” $130 Uses raster mapping Suitable for all brands of GPS

47. Suitable software (1) “OziExplorer” $130 Uses raster mapping Suitable for all brands of GPS Transferring data from Ozi is awkward

48. Suitable software (2) Garmin “Mapsource”

49. Suitable software (2) Garmin “Mapsource” Free with Garmin GPS

50. Suitable software (2) Garmin “Mapsource” Free with Garmin GPS Uses Vector mapping

51. Suitable software (2) Garmin “Mapsource” Free with Garmin GPS Uses Vector mapping Allows easy transfer of data to other programs (eg Excel)

54. Some possibilities Real aircraft - loop the loop Model aircraft Racing cars, dragsters, motorbikes Skydivers, bungee jumpers Yacht racing Theme park rides Relative motion on moving ship

55. Cost? Cheap GPS ≈ $100 Garmin GPS Map 60 CSx ≈ $470 OziExplorer $130 Oztopo maps for Garmin (all of Australia) $229