1

High Sensitivity Signal Processing for Modern GNSS Receivers

Dr. TA Hai TungSoICT – NAVIS Centre

Hanoi University of Science and Technology

2

Contents:

• Principles of satellite navigation• Global Navigation Satellite Systems: GPS, Galileo• Signal processing chain in GNSS receivers• High sensitivity navigation signal processing• Experiments and Software Receiver demo

History of Navigation.

33

Where am I? How do I get to my destination? These questions are as old as the history of mankind.

Stone Age Celestial Age

LORAN GNSSRadio Age

4

Direction Finding (Angle of Arrival)

5

Hyperbolic Navigation(Time Difference of Arrival - TDOA)

6

Tri-lateration

7

Doppler Navigation

• If a satellite transmits a model for its orbit as a function of time, its relative velocity w.r.t. a given point can be calculated

• This relative velocity (Doppler) profile is unique• Reversing this idea, given the orbit model and a

series of Doppler measurements from the satellite, position can be calculated

8

Radionavigation SystemsHyperbolic

- Loran C (Chayka)- Decca- Omega- Cellular mobile

Direction-finding

- VOR/DME- TACAN- Microwave Landing System

Trilateration- GPS/Glonass/Galileo/Compass

- Cellular Mobile

- Locata

- Transit (US)- Cicada (USSR)

Doppler

Land-based

Satellite-based

9

10

SATELLITE NAVIGATION (GPS TECHNOLOGY)

Position Estimation in SatNav

1111

(x,y,z)

•Tri-lateration technique •Number of required visible satellites: 3 + 1 for

clock bias

(x,y,z,dt)

12

How to measure ranges?

13

How to measure ranges? (#2)

14

How to measure ranges? (#3)

15

How to measure ranges? (#4)

16

How to measure ranges? (#5)

17

How to compute the position?

18

19

How to compute the position? (#2)

20

How to compute the position? (#3)

21

How to compute the position? (#4)Taylor Expansion

22

How to compute the position? (#5)Navigation Equations

23

How to compute the position? (#6)

24

How to compute the position? (#7)

25

How to compute the position? (#8)

26

How to estimate accuracy?

27

How to estimate accuracy? (#2)

28

How to estimate accuracy? (#3)

29

How to estimate accuracy? (#4)

30

How to estimate accuracy? (#5)

31

How to estimate accuracy? (#5)covariance of positioning error

32

33

34

How to estimate accuracy? (#6)Dilution of Precision

35

36

37

38

39

Measurement Errors Sources

40

41

42

43

Ionospheric Delay

44

45

46

47

48

Tropospheric Delay

49

50