gnss-r, an innovative remote sensing tool for the mekong delta, jamila beckheinrich, brest 2013...
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GNSS-R, an Innovative Remote Sensing Tool for the Mekong Delta, Jamila Beckheinrich, Brest 2013Slide 1
GNSS Reflectometry, an Innovative Remote Sensing Tool for the Mekong Delta
J. Beckheinrich1, S. Schön2, G. Beyerle1, M. Semmling1, H. Apel1, J. Wickert1
1.GFZ, German Research Center for Geosciences, Potsdam, Germany
2.Leibniz University Hannover, Institute of Geodesy, Hannover, Germany
Space Reflecto 2013Brest, France
WP within the WISDOM project
Experimental Setup
Data Analysis
Latest Results
Conclusion and Outlook
Slide 2
WP within the WISDOM project
Experimental Setup
Data Analysis
Latest Results
Conclusion and Outlook
Slide 3
Slide 4
WP within the WISDOM Project:
Severe changes could be observed in the Mekong Delta:
extreme flood eventsimportant to monitor coastal
area with dense population
Test the possibility of using low elevation GNSS-Reflectometry for flood monitoring of the Mekong Delta
Develop and implement algorithms to process GPS signals into water levels
WP within the WISDOM project
Experimental Setup
Data Analysis
Latest Results
Conclusion and Outlook
Slide 5
Experimental setup:
Slide 6
Gauge
Measurement location
6 km 150 m
Experimental setup:
Two time series with two different antenna heights above the reflecting surface:
Terrace with ~10 m
Roof with ~20 m
Slide 7
Experimental setup:
Two antennas (Antcom):RHCP oriented to the zenith (direct signal)
LHCP tilted to the reflecting surface (reflected signal)
Slide 8
L1/L2 GPS RHCP
RHCP/ LHCPL1/L2 GPS
Direct signal
Reflected signal
Experimental setup:
Slide 9
a: GORS
b: Control unit
c: Laptop
d: External Hard Disk
WP within the WISDOM project
Experimental Setup
Data Analysis
Latest Results
Conclusion and Outlook
Slide 10
Antenna height ~ 10 m ~ 20 m
Recording time ~84 h ~60 h
Reflection events ~194 h ~ 191
Continuous phase observations > 2 min. ~26 % ~ 29 %
Continuous phase observations > 10 min ~22 % ~ 22%
Slide 11
Data Analysis:
Slide 12
Data Analysis:
Roof (~20 m)
Hotel
River
Terrace (~10 m)
Incoherent Observations Coherent Observations
Slide 13
Data Analysis:
Slide 14
Data Analysis:
River
Receiver
Reflection track
Empirical Mode Decomposition (EMD)
Method:1998 Huang [1]
2008 and 2013 Hirrle [2]
Motivation:Fourier Transform assume stationarity and linearity
Wavelet Transform assume linearity
EMD is a fully data-driven signal analysis
No need of an a priori base
Slide 15
Data Analysis:
𝑥 (𝑡 )=∑𝑖=1
𝑛
𝑥 𝑖 (𝑡 )+𝑇 (𝑡 )
Slide 16
Intrinsic Mode Functions (IMF)
Data Analysis:
𝑥𝑖𝑇 (𝑡)
IMF
Trend
𝑥 (𝑡) Input signal
Slide 17
Data Analysis:
Input Signal
Slide 18
Data Analysis:
Maxima and minima
Slide 19
Data Analysis:
Cubic spline interpolation
Slide 20
Data Analysis:
Mean
Slide 21
Data Analysis:
Resulting Signal
𝑥 (𝑡 )=∑𝑖=1
𝑛
𝑥 𝑖 (𝑡 )+𝑇 (𝑡 )
Slide 22
𝑥𝑑𝑖𝑓𝑓=𝑥 (𝑡 )−𝑥𝑖 (𝑡)=∑𝑖=2
𝑛
𝑥 𝑖 (𝑡 )+𝑇 (𝑡 )
Intrinsic Mode Functions (IMF)
Data Analysis:
𝑥𝑖𝑇 (𝑡)
IMF
Trend
𝑥 (𝑡) Input signal
Slide 23
Data Analysis:
Trend
Slide 24
Data Analysis:
Horizontal Reflector h = 13 m Vertical Reflector h = 1 m
Slide 25
Data Analysis:
IMF 1 vs Horizontal Reflection IMF 2 vs Vertical Reflection
Completness
Slide 26
Data Analysis:
PRN 12, Vietnam, Can Tho City, 28th February 2012
Fre
qu
ency
Slide 27
Fre
qu
ency
Data Analysis:
PRN 12, Vietnam, Can Tho City, 28th February 2012
Slide 28
First results: EMD Observations
WP within the WISDOM project
Experimental Setup
Data Analysis
Latest Results
Conclusion and Outlook
Slide 29
Slide 30
Latest Results:
EMD
Beckheinrich J. et al, GNSS Reflectometry: Innovative Flood Monitoring at the Mekong Delta, submitted JSTARS august 2013
Slide 31
Latest Results:
Vietnam, Can Tho City, 29th February 2012
With EMD: std (1σ) = 0.05 m Without EMD: std (1σ) = 0.12 m
Slide 32
Latest Results:
Vietnam, Can Tho City, 29th February 2012
WP within the WISDOM project
Experimental Setup
Data Analysis
Latest Results
Conclusion and Outlook
Slide 33
Although the measurement were made under challenging conditions we could reach a correlation of 0.84 with the data recorded from a gauge instrument
GNSS-R could contribute to monitor water level changes of the Mekong Delta
Improvement of stochastic and functional modelDetermination of sigma reflected signals (Experiment)Include Phase Wind up effectAmplitude
Better understanding of the EMD parameters and there impact on the IMF decomposition
Slide 34
Conclusion and Outlook:
[1] Huang N.E. et al., The Empirical Mode Decomposition and the Hilbert Spectrum for non linear and non-stationary time series analysis, Proc. R. Soc. London A, (1998), pp. 903-995
[2] Hirrle A. Et al., Estimation of Multipath Parameters using Hilbert Huang Transform, ION GNSS, Nashville, Tennessee, USA, 2012
[3] Beckheinrich J. et al., GNSS Reflectometry: Innovative Flood Monitoring at the Mekong Delta, submitted at JSTARS, August 2013
Slide 35
References:
Slide 37
First Fresnel zone, 10 m height antenna
First Fresnel zone, 20 m antenna height
Slide 38