Ph.D. thesis presentation by Andrea Barucci Advancements on interferometric radar: studies and applications

1. CorsodiDottorato
in IngegneriadeiSistemiElettronici
XXIII ciclo
Advancements on interferometric radar:
studies and applications
Coordinatore: Prof. Carlo Atzeni
Tutor: Prof. Massimiliano Pieraccini
Candidato: Andrea Barucci

2. Introduction

3. Applicationofadvancedmonitoringtechniquesto the monitoring and
characterizationofquarriesfor the profit optimization and for the
safety and environmentalprotectionof the quarrymining

4. CWSF Ground BasedSynthetic Aperture Interferometric radar
CentralFrequency 16.75 GHz
Banwidth 400 MHz
Tx Power 26 dBm EIRP
SAR scan length 2m
SAR acquisition time 4 min (minimum)
Power consumption < 40 W

5. Radar installation
Powersupply system
Wide angle SAR

6. Measurementcampaign
Start 16 feb 2009
End 25 mar 2009
Days of measurement 39
N. Radar acquisitions about 600 (1 every 2 hours)

7. RCS SAR image
Range 0.5 m
resolution
Cross 5mrad
range
resolution

8. Interferograms in scarp area
(m)
(m)
(m)
(m) (m) (m)
(m)
(m)
(m) (m) (m) (m)
Eachinterferogramrelatesto a timelapseoftwohours

9. Interferometricanalysisin the wallarea
1. PSsselection
DispersionIndex
About 50.000 PSsselected in
all the area
2.
Atmosphericmeanphasescreen
removal
3. Calculationofdisplacements

10. Interferometricanalysis in the wallarea
Selectionof 50 pixels in the wall
cumulated displacement
Timeperiod: 23 days

11. Interferometricanalysis in the wallarea
cumulated displacement
Selectionof 50 pixels in the wall
Timeperiod: 3days

12. Validationof the methodby a corner reflector
Distance: 800 m

13. Actual Measured Error
(mm) (mm) (mm)
2.0 2.05 0.05
1.0 0.89 0.11
0.5 0.53 0.03

14. Interferometric DEM of the quarry
Laser
Conclusions
• A ground based Synthetic Aperture Interferometer was
successfully tested for the first time in a quarry.
• The system showed an accuracy of few tenths of a millimeter
in displacement’s measurement, over a long period and at
800 meters of distance.
• In short term measurements a simulation showed an
accuracy in measurement of displacements of the order of a
tenth of a millimeter.
• DEM reconstruction showed some limitations especially in
high slopes.
Radar

15. Universal fluctuations in tropospheric radar measurements
Introduction
• Long term atmospheric artifacts on GB-SAR are known
• Radar signal propagation through tropospheric turbulence is a new
research topic
Experiment
Data
Analysis
S. T. Bramwell, P. C.W. Holdsworth, and J.-F. Pinton,
Classic: Modern:
Universality of rare fluctuations in turbulence and critical
phenomena, Nature 396, 1998
Fluctuations of signal
Correlated systems, Physical Review Letters [2000, 2005, 2008]
as a function of
Gumbel statistics
turbulence

16. Firenzuola scenario

17. Scenario and raw-data
CR Ultrasonic Anemometer / Radar sampling freq Range Observational time
distance Weather sensor Resolution
65 m 4/1Hz About 50 Hz 1m 6h

18. Detrending – High-pass filter
• Turbulent phenomena occur
at the micro scale,
corresponding to distances
shorter than 1 km, which are
the usual working distances for
a GB-SAR.
• We use a moving average to
remove the fluctuations on
temporal scales greater than 30
minutes

19. Time series data analysis
We use overlapping
temporal windows, with
length of about 30
minutes:
- About 10^5 points ->
rare fluctuations & good
statistics
- Constant Reynolds
number
Turbulent Kinetic
Energy (TKE) is a
measure of the
turbulence

20. Wind fluctuations dependency
R = 0.98 R = 0.89

21. Radar signal statistics & Correlated Systems
Radar signal through a Turbulence
turbulent atmosphere Correlated
Ising& 2D XY
Systems
River water
level
Forest fires,
etc.
Generalized
Gumbel PDF
Global quantity
Radar Data
statistics?

22. Generalized Gumbel
• Generalized Gumbel describes the fluctuations in Correlated Systems, its
shape depends on a real parameter a
• As a varies, the shape of the distribution varies from a completely
asymmetric, negatively skewed, distribution to a symmetric one quite similar
to a Gaussian function
• The parameter a has been proposed to be inversely related to the correlation
length of the system

23. Data distribution
• Fit of the data with the GG(a)
• Amplitude statistic appears to fit with the GG
• Phase statistic doesn’t show the same behaviour
Amplitude
• The radar data distributions calculated over the
analysis windows show different means and
standard deviations new method from Nature
Phase

24. • a is determined by the turbulence strength
• In hard windy conditions, a is nearly equal to pi/2 which is the value
for which GGa is approximately the Bramwell-Holdsworth-Pinton
distribution observed in turbulence and critical systems
Andrea Barucci

25. Conclusions
• The radar signal statistic:
– It is influenced by the turbulence
– It is a global quantity able to measure the “correlation of the
atmosphere” at the micro-scale
• We confirm the adequacy of the Gumbel statistic to describe
highly correlated complex systems
• SAR images - turbulence: work in progress
• Paper published by Europhysics Letters: A. Barucci, G. Macaluso, D. Mecatti, L. Noferini, D. Fanelli, A.
Facchini, M. Materassi, M. Pieraccini and C. Atzeni, Universal fluctuations in tropospheric radar
measurements, EPL, 89 (2010) 20006, DOI 10.1209/0295-5075/89/20006