Global Positioning System (GPS)

1. Global Positioning System(GPS)

2. Learning Objectives: By the end of this topic you should be able to: • describe how satellite communications systems are used in global positioning, • describe the advantages and disadvantages of using satellites for global positioning

3. GPS • 24 satellites in Low Earth Orbit • put in place by US military • available to anyone with a receiver • used in marine, aviation & terrestrial navigation

4. GPS • need at least 3 satellites ‘in range’ • line of sight • uses ‘trilateration’ to determine position

5. GPS • 6 satellites used (green) • 1 low power signal (red - going out of range?)

6. GPS receivers • inexpensive, • from <£100 • can be a handheld device • portable • walking, cycling …. • can be used in remote locations • text readout of latitude & longitude • built-in software can calculate speed and direction

7. GPS receivers

8. GPS plotters • add map data to system • plot current position on map

9. GPS plotters

10. GPS plotters

11. GPS PDA + GPS card

12. Satellite Navigation • requires Global Positioning System (GPS) • at least three satellites required for fix • radio signal, line of sight • accurate to within a kilometre • use of receiver on vehicle to decode the signals • current position shown on a screen map • overlay other data: • points of interest (POI) e.g. petrol stations, hotels • traffic cameras • roadworks, delays - recalculate & display new route

13. Advantages of GPS/Sat Nav • accuracy can be as good as 30cm • can find lost people from lat/long or position • no need to use map • concentrate on driving • save time by not planning journeys • software does it automatically • new route calculated if driver makes an error • maps can be updated from the Internet

14. Disadvantages of GPS/Satnav • requires line of sight access to satellites • no use in a building or in tunnels • atmospheric conditions can affect accuracy • system may not have up-to-date maps • driver given incorrect instructions • over reliance on satnav may mean loss of map skills • may get lost if system fails • operating system while driving is dangerous • destinations may not be recognised by system

15. Satellite Navigation Communicating with unit: • push buttons to set instructions, • voice to dictate instructions (voice recognition), • keyboard to type instructions, • use of predictive text, • touch screen, • joystick, • CDROM, DVD or mobile phone to input maps

16. Satellite Navigation Communicating with unit:

17. Satellite Navigation Communicating with unit:

18. Satellite Navigation Communicating with unit:

19. Satellite Navigation Communicating with unit:

20. Satellite Navigation Communicating with unit:

21. Satellite Navigation Communicating with user: • Visual Display Unit (screen) showing turns on map

22. Satellite Navigation Communicating with user: • Visual Display Unit (screen) showing turns on map

23. Satellite Navigation Communicating with user: • Visual Display Unit (screen) showing turns on map

24. Satellite Navigation Communicating with user: • Visual Display Unit (screen) showing turns on map • audio communication - voice synthesis

25. Satellite Navigation Communicating with user: • Visual Display Unit (screen) showing turns on map • audio communication - voice synthesis

26. Satellite Navigation Communicating with user: • Visual Display Unit (screen) showing turns on map • audio communication - voice synthesis

27. Satellite Navigation Communicating with user: • Visual Display Unit (screen) showing turns on map • audio communication - voice synthesis • head up display (HUD) available

28. Satellite Navigation Head Up Display:

29. Satellite Navigation Head Up Display:

30. Satellite Navigation Head Up Display (night vision):

31. Satellite Navigation Head Up Display (night vision):