Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S....
-
Upload
madeline-thomas -
Category
Documents
-
view
218 -
download
1
Transcript of Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S....
![Page 1: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/1.jpg)
Ionospheric mitigation schemes and their consequences for BIOMASS product quality
O. French & S. Quegan, University of Sheffield, UK
J. Chen, Beihang University, China
ESA, Holland, 20th May 2010
Task 200: Definition of Ionospheric Correction Schemes
![Page 2: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/2.jpg)
Ionospheric Scintillation - Outline
• Summary of previous results
• Effect of 9m antenna
• GPS TEC data
• SAR simulator
• Correction strategies
![Page 3: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/3.jpg)
Ionospheric Scintillation: Local Time
Summary
• Scintillation effects severe for Boreal latitudes at all local times
• For temperate and equatorial zones, much reduced levels of scintillation in general...
• ...BUT: severe post-dusk scintillations in the equatorial zone for orbits with local time later than 20:00.
![Page 4: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/4.jpg)
Effect of 9m Antenna
• Shorter antenna of 9m does not change the previous conclusions, in fact very little apparent effect on PSF.
• However, increased resolution drastically increases required computing power to simulate a given area.
-Increased synthetic aperture;-Increased resolution on aperture;-Number of data points for 2D screen increases as d-4.
• Developed 1D slice simulator for which required number of datapoints scales as d-2.
![Page 5: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/5.jpg)
GPS TEC data
• Spatial resolution at 2.5° latitude, 5 ° in longitude.• Temporal resolution of 2 hours.
![Page 6: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/6.jpg)
GPS TEC data
![Page 7: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/7.jpg)
GPS TEC data
• Still to do: perform comparison of IRI and GPS TEC data.
• Expect IRI to be “smoother” than GPS data- Compare IRI with window averaged GPS data
• GPS likely to be better data source - GPS data accurate within 3-5 TECU- IRI comprises a model fitted to experimental data
![Page 8: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/8.jpg)
Correction Strategies
• 1D SAR simulator built that images point target • Incorporates arbitrary phase perturbation across synthetic aperture
- Polynomial, degree n;- 1D Ionospheric phase simulations.
• Simple multi-aperture mapdrift (MAM) correction strategy employed.
![Page 9: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/9.jpg)
Correction Strategies: MAM
• Phase error modelled as
• Require N sub-apertures to estimate the ak’s
• Decrease in SNR with increasing number of sub-apertures limits N
• Simulations performed for 2π phase error per term in polynomial, i.e. ak = 2π/Lk
![Page 10: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/10.jpg)
Correction Strategies: Mapdrift
Uncorrected and corrected images for N=4
![Page 11: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/11.jpg)
Correction Strategies: Mapdrift
Uncorrected and corrected images for N=8
![Page 12: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/12.jpg)
Correction Strategies: Mapdrift
Uncorrected and corrected images for N=4 and with simulated ionospheric phase
![Page 13: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/13.jpg)
Correction Strategies: Mapdrift
• Mapdrift ill-equipped to correct for ionospheric scintillation
• Probably due to high order of taylor expansion required to capture phase perturbations
• Alternative is PGA which does not rely on model for phase error
![Page 14: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/14.jpg)
Ionospheric mitigation schemes and their consequences for BIOMASS product quality
O. French & S. Quegan, University of Sheffield, UK
J. Chen, Beihang University, China
ESA, Holland, 20th May 2010
Task 500: Definition of Calibration Scheme
![Page 15: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/15.jpg)
Calibration - Outline
• Fujita three target approach
• Chen-Quegan compact polarisation approach
• Preliminary results for HV full polarisation approach
• Further work
![Page 16: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/16.jpg)
Fujita Three Target ApproachAssumptions
• crosstalk same for transmit and receive channel;• discount all quadratic terms;• zero-mean complex Gaussian noise.
Five parameters (4 complex, 1 real): • transmit and receive channel imbalance, Fr and Ft;
• hv and vh crosstalk, C1 and C2;• Faraday rotation, Ω.
Masaharu Fujita, ‘Polarimetric Calibration of Space SAR Data Subject to Faraday Rotation – A Three-Target Approach’, IEEE 2005
![Page 17: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/17.jpg)
Fujita Three Target Approach
System model: M = RTFSFT + N
where
are transmit and receive distortion matrices,
is Faraday rotation matrix. N is additive noise.
![Page 18: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/18.jpg)
Fujita Three Target Approach
![Page 19: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/19.jpg)
Fujita Three Target Approach
Simulation parameters used (taken from original paper)• Fr = 0.9;• Ft = 0.9;• C1 = 0.1;• C2 = -0.1;• Ω from 0 to 360°;• Additive noise -20dB in power;• No error in scattering matrices.
Two estimators for each quantity, denoted a and b
![Page 20: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/20.jpg)
Fujita Three Target Approach
Faraday Rotation, Ω
![Page 21: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/21.jpg)
Fujita Three Target Approach
Receive channel imbalance, FR
![Page 22: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/22.jpg)
Fujita Three Target Approach
Transmit channel imbalance, FT
![Page 23: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/23.jpg)
Fujita Three Target Approach
vh crosstalk, C1
![Page 24: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/24.jpg)
Fujita Three Target Approach
hv crosstalk, C2
![Page 25: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/25.jpg)
Fujita Three Target Approach
vh crosstalk, C1 hv crosstalk, C2
![Page 26: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/26.jpg)
Fujita Three Target Approach
Introduce phase into single quantity, C1
• Fr = 0.9;• Ft = 0.9;• C1 = 0.1 exp (iπ/12);• C2 = -0.1;• Ω from 0 to 360°;• Additive noise -20dB in power;• No error in scattering matrices.
![Page 27: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/27.jpg)
Fujita Three Target Approach
Amplitude Phasevh crosstalk, C1
![Page 28: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/28.jpg)
Fujita Three Target Approach
Amplitude PhaseTransmit channel imbalance, Ft
![Page 29: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/29.jpg)
Fujita Three Target Approach
Limitations of Fujita approach:• Assumes equivalence of transmit and receive crosstalk• Poor phase results• Discounts all quadratic terms• Does not consider large TEC/FR
Incorporate GNSS TEC estimator
22
round
GNSSF
![Page 30: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/30.jpg)
Chen-Quegan Approach
• Good results for compact polarisation
• System model: transmit in right-circular polarised, receive in linear H,V.
2
1
1
2
cossin
sincos1
2
1,
N
N
eej
ee
SS
SS
ferA
M
Mj
cj
jc
j
VVVH
HVHHj
RV
RH
c
cc
V
H
jjjT
T
1
1
2
111
2
1
![Page 31: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/31.jpg)
Chen-Quegan Approach
• Five parameters:- Circular crosstalk on transmit, δc;- Crosstalk on receive, δ2 (hv) and δ1 (vh);- Channel imbalance on receive, f;- Faraday rotation, Ω.
• δc and f calculated first, ignoring quadratic terms
• All other quantities derived from these including quadratic terms
• Estimators optimised
![Page 32: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/32.jpg)
Chen-Quegan Approach
• Uses at most 4 calibrators from- PARCx- PARCy Active- PARCp- Dihedral- Trihedral Passive- Gridded trihedral (x 2)
![Page 33: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/33.jpg)
Chen-Quegan Approach
Amplitude PhaseChannel imbalance, f
|1| = |2 |= 0.1, |c| =0.32, arg{1}= arg{2}= arg{c}=0, = /4
arg{f} = /3 |f | = 1.5
![Page 34: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/34.jpg)
Chen-Quegan Approach
Amplitude PhaseCrosstalk, 1
|f | = 1.5, arg{f} = /3, |2 |= 0.1, |c| =0.32, arg{2}= arg{c}=0, = /4
arg{}=0 |=0.1
![Page 35: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/35.jpg)
Chen-Quegan Approach
• Excellent results for compact polarisation - Amplitude- Phase
• Reduced set of assumptions- Quadratic terms only initially discarded
• Need to extend to full HV polarimetric case
![Page 36: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/36.jpg)
Full Polarisation Scheme
System model: M = RTFSFT + N
Where now
are transmit and receive distortion matrices,
is Faraday rotation matrix. N is additive noise.
![Page 37: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/37.jpg)
Full Polarisation Scheme
Reduced assumptions• discount some quadratic terms;• zero-mean complex Gaussian noise.
Seven parameters (6 complex, 1 real): • transmit and receive channel imbalance, Fr and Ft;
• receive crosstalk, Cr1 and Cr2;• transmit crosstalk, Ct1 and Ct2; • Faraday rotation, Ω.
Preliminary results with same values as previously, using PARCx, PARCy, GT1 and GT2 calibrators.
![Page 38: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/38.jpg)
Full Polarisation Scheme
Faraday rotation, Ω
![Page 39: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/39.jpg)
Full Polarisation Scheme
Amplitude PhaseTransmit channel imbalance, Ft
![Page 40: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/40.jpg)
Full Polarisation Scheme
Amplitude PhaseReceive channel imbalance, Fr
![Page 41: Ionospheric mitigation schemes and their consequences for BIOMASS product quality O. French & S. Quegan, University of Sheffield, UK J. Chen, Beihang University,](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649e985503460f94b9b758/html5/thumbnails/41.jpg)
Full Polarisation Scheme
• Preliminary results show better (in)sensitivity to phase in crosstalk
Future work• Full analysis needs to be performed using method of Chen & Quegan.• Incorporate GNSS FR estimator• Consider suitability of calibrators