1. Signal processing algorithms for GNSS
receiver
Baharak Soltanian
Tampere University of Technology,
Finland
Presentation for Doctorate of Technology
Friday 11th September, 2015

2. 1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
Outline
1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
Signal processing algorithms for GNSS receiver –
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3. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
Signal processing algorithms for GNSS receiver –
B. Soltanian 3/38

4. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
1 Introduction
History.
Invention of GPS.
Global Positioning System (GPS)
Fundamental of GPS signal
2 Thesis objective.
3 Solution.
4 Conclusion
Signal processing algorithms for GNSS receiver –
B. Soltanian 4/38

5. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
History of navigation.
Directing vessels upon the open sea
traditional practice
geometry
astronomy
special instruments
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6. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Cont.
Astronavigation
use of angular measurements (sights) between celestial
bodies and the visible horizon to locate one’s position on
the globe, on land as well as at sea.
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7. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
1 Introduction
History.
Invention of GPS.
Global Positioning System (GPS)
Fundamental of GPS signal
2 Thesis objective.
3 Solution.
4 Conclusion
Signal processing algorithms for GNSS receiver –
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8. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
How Global Navigation Satellite System was invented?
Originally designed for military in the 1960s.
Inspiration coming from the launch of the Soviet spacecraft
Sputnik in 1957.
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9. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
How popular it becomes?
Smart phone.
Stand alone.
Wearable devices such as smart watches.
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10. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
1 Introduction
History.
Invention of GPS.
Global Positioning System (GPS)
Fundamental of GPS signal
2 Thesis objective.
3 Solution.
4 Conclusion
Signal processing algorithms for GNSS receiver –
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11. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
How it works.
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12. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Cont.
Definition: GNSS is a system of satellites that provide
autonomous geo-spatial positioning with global coverage.
Types:
Global Positioning System (GPS): consists of up to 32
satellites in six different orbital planes.
Galileo: The European Union and European Space Agency
agreed in March 2002 to introduce their own alternative to
GPS, called the Galileo positioning system.
GLONASS: Russian Globbal Navigation Satellite System
which was fully functioning in 1995. After collapse of the
Soviet Union it fell into disrepair. It was recovered and fully
restored in 2011.
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13. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Basic idea.
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14. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
1 Introduction
History.
Invention of GPS.
Global Positioning System (GPS)
Fundamental of GPS signal
2 Thesis objective.
3 Solution.
4 Conclusion
Signal processing algorithms for GNSS receiver –
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15. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
GPS Signals.
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16. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Cont.
The SVs transmit two microwave carrier signals.
The L1 frequency (1575.42 MHz) carries the navigation
message.
The L2 frequency (1227.60 MHz) is used to measure the
ionospheric delay.
The C/A Code (Coarse Acquisition):
modulates the L1 carrier phase.
It is repeated every 1 ms
Pseudo Random Noise (PRN) Code.
Spreading the spectrum over a 1 MHz bandwidth.
More resistance to noise and interference.
Its length is 1023 chips (one millisecond).
There is a different C/A code PRN for each SV.
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17. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Pseudo Random Noise (PRN).
Code-phase is a random variable, ∈ [0, 1023]
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18. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Auto-correlation.
Maximum correlation with itself.
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19. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Cross-correlation.
Minimum cross-correlation with other PRN codes.
Minimum correlation with its own shifted version.
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20. 1 Introduction
History.
Invention of GPS.
Global Positioning
System (GPS)
Fundamental of GPS
signal
2 Thesis objective.
3 Solution.
4 Conclusion
Introduction
Doppler frequency shift.
The Doppler effect (or Doppler shift) is the change in
frequency of a wave (or other periodic event) for an observer
moving relative to its source.
The Soviet Union launched the first man-made satellite,
Sputnik 1, in 1957. Two American physicists, William Guier
and George Weiffenbach, at Johns Hopkins’s Applied
Physics Laboratory (APL), decided to monitor Sputnik’s
radio transmissions. Within hours they realized that,
because of the Doppler effect, they could pinpoint where the
satellite was along its orbit.
For GPS signals fd ∈ [−10, + 10]kHz
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21. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
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22. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
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23. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
Thesis objective.
First generation of GPS (probably)
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24. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
Thesis objective.
Cont.
To reduce the complexity of acquisition algorithm in GPS
devices.
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25. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
Thesis objective.
Cont.
Make it more suitable for wearable devices.
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26. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
Thesis objective.
GPS module.
Arduino + GPS module + SD card module
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27. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
Thesis objective.
Cont.
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28. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
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29. 1 Introduction
2 Thesis objective.
Complexity problem.
Acquisition stage.
3 Solution.
4 Conclusion
Thesis objective.
Types of acquisition in GPS devices.
Time domain
Suitable for application-specific integrated circuit
(ASIC)-based devices.
Time consuming for Software-defined radio (SDR).
Frequency domain
Suitable for Software-defined radio (SDR).
High complexity particularly due to required IFFTs.
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30. 1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
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31. 1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
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32. 1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
Solution.
Utilization of multi-rate signal processing for GNSS-SDR
receivers.
Decimation.
Proposed a new architecture for the receivers.
Utilization of IIR filter.
Half-band IIR filter needs lowest multiplication rate per
input sample.
Utilized FFT-domain equalization concept to compensate
the nonideality caused by IIR filters.
Based on three complementary publications
Two publications on WDF filters
One publication on affect of decimation on acquisition stage.
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33. 1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
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34. 1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
Solution.
Utilization of binary tree search in GNSS receivers.
Modified binary search (MBS).
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35. 1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
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36. 1 Introduction
2 Thesis objective.
3 Solution.
Publication I
Publication II
Publication III
4 Conclusion
Solution.
Reduced-complexity FFT-based method for Doppler
estimation in GNSS receivers
Doppler search in FFT-domain.
Testing the presence of a code in FFT-domain utilizing
energy detection ideas.
Advantage Reduced number of I/FFTs if the CNR is
reasonably high.
Disadvantage Probability of misdetection is increased.
Solution Employed block averaging (BA) and none
coherent integration (NCI)
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37. 1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
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38. 1 Introduction
2 Thesis objective.
3 Solution.
4 Conclusion
Conclusion
Future work:
Optimized filters.
Probability of detection and misdetection for MBS.
Estimate the probability density function of the Doppler
frequency shift and take it in account for MBS.
Check the SNR wall for FFT-based Doppler search.
Effective overall search process with Doppler estimation in
FFT-domain.
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