1 SatNav

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High Sensitivity Signal Processing for Modern GNSS Receivers

Dr. TA Hai TungSoICT – NAVIS Centre

Hanoi University of Science and Technology

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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.

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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

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Direction Finding (Angle of Arrival)

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Hyperbolic Navigation(Time Difference of Arrival - TDOA)

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Tri-lateration

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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

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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

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SATELLITE NAVIGATION (GPS TECHNOLOGY)

Position Estimation in SatNav

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(x,y,z)

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

clock bias

(x,y,z,dt)

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How to measure ranges?

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How to measure ranges? (#2)

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How to measure ranges? (#3)

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How to measure ranges? (#4)

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How to measure ranges? (#5)

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How to compute the position?

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How to compute the position? (#2)

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How to compute the position? (#3)

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

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

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How to compute the position? (#6)

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How to compute the position? (#7)

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How to compute the position? (#8)

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How to estimate accuracy?

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How to estimate accuracy? (#2)

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How to estimate accuracy? (#3)

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How to estimate accuracy? (#4)

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How to estimate accuracy? (#5)

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

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

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Measurement Errors Sources

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Ionospheric Delay

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Tropospheric Delay

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