space reflecto 2013

Simulations and exploitation of GNSS-R signals from a 60-meter lighthouse for applications in

surface hydrology processes

Space Reflecto 2013

Nicolas ROUSSELLaurent LESTARQUIT

PhD advisers: Guillaume RAMILLIEN, Frédéric FRAPPART

04/05 novembre 2013

2

PlanIntroduction Simulations Field measurements

Introduction

Simulations

Field measurements

GNSS-based tide gauge system with SILICOM datalogger

Analysis of signal-to-noise ratio (SNR) series

4/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

PlanIntroduction Simulations Field measurements

Introduction

Simulations

Field measurements

GNSS-based tide gauge system with SILICOM datalogger

Analysis of signal-to-noise ratio (SNR) series

34/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Ground configuration Embedded configuration

Direct/reflected signals correlation Position of the specular reflection point Altimetry Properties of the reflection surface

(roughness)

Source : Institut de Ciències de l’Espai (http://www.ice.csic.es)

IntroductionIntroduction Simulations Field measurements

44/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

- 60

m -

IntroductionIntroduction Simulations Field measurements

The Cordouan Lighthouse (45°35’11’’N ; 1°10’24’’O)

54/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

PlanIntroduction Simulations Field measurements

Introduction

Simulations

Field measurements

GNSS-based tide gauge system with SILICOM datalogger

Analysis of signal-to-noise ratio (SNR) series

64/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Modeling the trajectories of GNSS electromagnetic waves that are reflected on the surface of the Earth, based on real ephemeris

Determine the potential of GNSS-R for mapping the characteristics of the reflecting surface

Explore different configurations of performing measurements and instrument installations:

variations in the reflectometer height, mask effects due to the terrain, satellites geometry, ...

Simulator development

SimulationsIntroduction Simulations Field measurements

74/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

84/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Determination of the position of the specular reflection points: 3 algorithms

- Approximation of the Earth into a local sphere

- Approximation of the Earth into a local ellipsoid

- DEM (Digital Elevation Model) integration

Correctness Computation speed

Gnu R

For further information : Simulations of direct and reflected waves trajectories for in situ GNSS-R experiments, submitted in Geosciences Model DevelopmentN. Roussel, F. Frappart, G. Ramillien, C. Desjardins, P. Gegout, F. Pérosanz, R. Biancale

SimulationsIntroduction Simulations Field measurements

94/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

SimulationsIntroduction Simulations Field measurements

Simulator outputs Simulations on the Cordouan lighthouse (45°35’11’’N ; 1°10’24’’O)

SimulationsIntroduction Simulations Field measurements

104/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Simulations over a week

SimulationsIntroduction Simulations Field measurements

114/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Simulations over a week

SimulationsIntroduction Simulations Field measurements

124/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Introduction

Simulations

Field measurements

GNSS-based tide gauge system with SILICOM datalogger

Analysis of signal-to-noise ratio (SNR) series

134/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

PlanIntroduction Simulations Field measurements

14

PlanIntroduction Simulations Field measurements

Introduction

Simulations

Field measurements

GNSS-based tide gauge system with SILICOM datalogger

Analysis of signal-to-noise ratio (SNR) series

4/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

SILICOM Data-LoggerData Logger

records and time tags a wide choice of supported RF GNSS signals

makes possible the characterization of the reflected signal and the development of algorithms for processing the GNSS-R signals.

SILICOM Data-loggerIntroduction Simulations Field measurements

154/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

31st may 2013 campaignData Logger

to collect GNSS-R signals, receiving the direct signal via a RHCP zenith-looking antenna, and the reflected signal via a LHCP nadir-looking antenna

Approx. 25 min of acquisitions, 25 MHz, 8 bits

SILICOM Data-loggerIntroduction Simulations Field measurements

164/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Acquisition

1 ms Doppler : [-5000:1:5000] Hz

Detection of 6 satellites :

- PRN12- PRN15- PRN17- PRN24- PRN25- PRN26

In agreement with the simulations

SILICOM Data-loggerIntroduction Simulations Field measurements

174/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Acquisition

Reflected signalDirect signal

PRN15 exemple : detection of the initial doppler

SILICOM Data-loggerIntroduction Simulations Field measurements

184/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Acquisition

Reflected signalDirect signal

PRN15 exemple : detection of the initial delay

SILICOM Data-loggerIntroduction Simulations Field measurements

194/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Correlation functionReflected signalDirect signal

SILICOM Data-loggerIntroduction Simulations Field measurements

1 ms 1 ms

100 ms100 ms

204/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Correlation function

SILICOM Data-loggerIntroduction Simulations Field measurements

Reflected signalDirect signal

1 ms 1 ms

100 ms100 ms

214/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Delay-Doppler Maps

SILICOM Data-loggerIntroduction Simulations Field measurements

244/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Tracking

SILICOM Data-loggerIntroduction Simulations Field measurements

234/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

Differences between direct and reflected paths – C/A PRN12

Time (s)

Dis

tanc

e (m

)

𝛿d=2h𝑠𝑖𝑛(𝜖) : satellite elevation

Determination of the C/A pseudo-distance for both direct and reflected signals The difference between both gives the extra distance traveled by the reflected wave

Tracking

Direct signal

𝛿d=2h𝑠𝑖𝑛(ϵ ) With the elevation Satellite Num Receiver height h (m)PRN12 57,47

PRN15 60,47

PRN17 57,75

PRN24 61,98

PRN25 61,66

PRN26 59,46

Mean 59,80 ± 1,92

SILICOM Data-loggerIntroduction Simulations Field measurements

234/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

25

PlanIntroduction Simulations Field measurements

Introduction

Simulations

Field measurements

GNSS-based tide gauge system with SILICOM datalogger

Analysis of signal-to-noise ratio (SNR) series

4/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

26

PlanIntroduction Simulations Field measurements

Introduction

Simulations

Field measurements

GNSS-based tide gauge system with SILICOM datalogger

Analysis of signal-to-noise ratio (SNR) series

4/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

phase difference between the direct signal and the reflected signal (multipath)

Direct signal amplitude

Multipath amplitude

x = sin θ :

SNR dataIntroduction Simulations Field measurements

Larson et al., GPS Sol., 2008

274/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

SNR dataIntroduction Simulations Field measurements

L2 SNR data

2nd order polynom

284/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

SNR dataIntroduction Simulations Field measurements

294/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

L2 SNR data

0 – 40° elevation filtration

SNR dataIntroduction Simulations Field measurements

L2 SNR data

304/5 November 2013 Space Reflecto – Nicolas ROUSSEL / Laurent LESTARQUIT

The whole 3 months time series is currently being analyzed in order to make the tide appear

Thanks for your attention !