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ASAR Processing Facility Status. Processor releases Internal calibration updates Processing parameter updates Auxiliary Files updates Future development Conclusions. Josep Closa ESA-ESRIN. Processor Version. Installation Date. PF-ASAR v3.01. 13-09-2002. PF-ASAR v3.02. 12-11-2002. - PowerPoint PPT Presentation
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Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
ASAR Processing Facility Status
Processor releases Internal calibration updates Processing parameter updates Auxiliary Files updates Future development Conclusions
Josep Closa
ESA-ESRIN
Page 2ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Processor Releases 3 new releases since the calibration workshop All releases preceded by the delivery of a standalone version
used to perform pre-validation before installation in the PDS Last version (3.03) to be installed within next week Products for the validation workshop processed with the
latest standalone version
Processor Version
Installation Date
PF-ASAR v3.01 13-09-2002
PF-ASAR v3.02 12-11-2002
PF-ASAR v3.03 Next week !!
Page 3ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Internal Calibration Updates High variations detected on the instrument gain calculated
from the calibration pulses specially in WS – SS4 and SS5
Page 4ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Internal Calibration Updates Strong modulation in the P2 (receive) calibration pulses not
detected by the pulse filtering based on nominal amplitudes Variation in the calculated gain due to wrong phase values
extracted from the calibration pulses
P2 amplitude in SS4
P2 amplitude in SS5
-25
-23
-21
-19
-17
-15
-13
1 2 3 4 5 6 7 8 9 10 11 12 13 14
SS1
SS2
SS3
SS4
SS5
Calculated Elevation Gain
Elevation gain filtering based on nominal chirp energy values
Page 5ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Calibration Pulse Compression Calibration pulse compression to extract the phase initially
performed with the reconstructed replica Artefacts on the chirp reconstruction from any corrupted
calibration pulse influence on the extracted phase
Calibration pulse compression performed with the nominal chirp
Page 6ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Calibration Pulse Compression
-200
-150
-100
-50
0
50
100
150
200
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31
-200
-150
-100
-50
0
50
100
150
200
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31
P2 extracted Phase with extracted chirp
P2 extracted Phase with nominal chirp
0
0.5
1
1.5
2
2.5
3
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31
Extracted
Nominal
P2 Phase standard deviation
-40
-35
-30
-25
-20
-15
-10
-5
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
SS5 nominal
SS5 extracted PF-ASAR
SS5 elevation gain nominal - extracted
Page 7ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Wave Mode Phase Estimation Variations in the elevation gain due to noisy phase values
introduced by the first sample in the calibration window Phase average within the window discarding the first sample Recalculation of the IS2 wave calibration constant
47.38 dB
Page 8ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Alternating Polarization Internal Calibration P1 pulses are saturated for some rows and P2 calibration pulses
are not present for some swaths for all calibration cycles: incorrect values of the elevation gain
Use of reference energy values for product normalization Same values are used for the different polarization combination
images Nominal values not available for IS5 and IS7. Refinement is needed
for the rest of swaths Different calibration constant values per beam
Page 9ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Processing Parameters Updates Change of range processing parameters following the change in
transmitted bandwidths to 16 MHz for IM / AP Changes impact the characterization / quality of all the IM / AP
products
Image Mode
Change in the IMP/ IMG processing bandwidths to keep range resolution: decrease of the SNR
Variation of processing gain with beam to compensate for bandwidth throw out in order to keep previous calibration constant values
Intermediate versions generating IMP/IMG products with higher range resolution
Future processor update to apply range multilooking on high incidence swaths: Higher ENL and SNR
Page 10ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Processing Parameters Update: IM
Total processed bandwidth for the IMM products set to 16 MHz Number of looks in IMM increased from 5 to 10 overlapped looks:
throughoutput implications Future update to make the number of overlapped looks beam
dependent No change for the IMS products: all expected range resolutions
values are ~9.22 m
Beam Fraction bandwidth (16 MHz) ProcessedBandwidth
Gain (linear)
IS1 1.0 16.0 MHz 8.0 E5
IS2 1.0 16.0 MHz 8.0 E5
IS3 0.8 12.8 MHz 8.99E5
IS4 0.67 10.72 MHz 9.74E5
IS5 0.6 9.6 MHz 10.4E5
IS6 0.55 8.8 MHz 10.8E5
IS7 0.51 8.16 MHz 11.2E5
Page 11ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Processing Parameters Update: AP APP/ APG / APM processing gains update in order not to saturate the
transponders and maximize the cross-polarization values
Some products in intermediate versions affected by range modulations due to processing parameters different from instrument parameters
APM product number of range looks changed from 5 to 10 overlapped looks
Future development to include two overlapped looks in APP/APG and make the number of range looks beam dependent
No changes on the APS processing parameters: expected range resolution ~8.3 m
Beam Gain
IS1 2.0 dB
IS2 2.0 dB
IS3 2.0 dB
IS4 2.0 dB
IS5 5.0 dB
IS6 5.0 dB
IS7 5.0 dB
Beam GainIS1 14.3 dB
IS2 14.3 dB
IS3 14.3 dB
IS4 14.3 dB
IS5 14.3 dB
IS6 14.3 dB
IS7 14.3 dB
Page 12ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Processing Parameters Update: WSM / GMM Following the update in the transmitted bandwidths, the number
of looks and the look bandwidths in range have been updated Parameter changes guarantee consistent range resolution at the
center of the swath and increase the ENL Look overlap around ~40 % Processing gains per beam modified to achieve radiometric
continuity No beam merging performed over the beam overlap area Beam Transmitted
BandwidthLook
BandwidthNumber of
Looks
SS1 14.75 MHz 3.35 MHz 7
SS2 12.86 MHz 2.80 MHz 7
SS3 10.48 MHz 2.38 MHz 7
SS4 9.54 MHz 2.06 MHz 7
SS5 8.48 MHz 1.90 MHz 7
Beam WSM Gain GMM Gain
SS1 10.15 42.66
SS2 9.5 35.75
SS3 1.0 35.40
SS4 9.4 34.40
SS5 9.9 33.46
Page 13ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Other Updates
Range Compression performed with the nominal chirp function
Detection of calibration pulses based on the amplitude
thresholding
Solution to the generation of the cross spectra
Wave Mode Level 2 algorithm clean up
Wide Swath Doppler Ambiguity estimation from data instead of
orbit
Alternating Polarization Doppler refinement based on azimuth
antenna patterns turned on
Page 14ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Solution to Specan IRF degradation Problem affecting the range response of ALL products
processed with the Specan algorithm ASA_IMM_1P ASA_APP_1P ASA_APG_1P ASA_APM_1P ASA_WSM_1P ASA_GMM_1P
Problem solved by adding some zero padding to the RIVs and stitching the regions before looks extraction
Buffering problems introduced by the solution already solved
Page 15ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Auxiliary Parameters Update ASA_INS_AX
Updated nominal calibration pulse amplitude and phase values
Updated chirp coefficients for 16 MHz transmitted chirp Updated azimuth antenna patterns generated from MS New instrument WSM number of burst per beam to avoid
azimuth ambiguities ( < -21 dB) and obtain consistent azimuth resolution for all the beams (~120 m)
Updated embedded row patterns: slight normalization variation
Beam Number of pulses / burst
SS1 50
SS2 65
SS3 55
SS4 71
SS5 60
Page 16ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Auxiliary Parameters Update ASA_XCA_AX
Updated calibration constants from the cal / val review results
Updated co- and cross-polarization antenna patterns (HV-IS3, IS6 missing)
ASA_XCH_AX Updated external characterization factors for both
polarizations: slight normalization variation ASA_CON_AX: No update
Page 17ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Open Issues - Future Development (1)
Number of extracted range looks to be set to 2 for IMP / IMG / APP / APG products
Number of extracted range looks to be beam dependent for IMP / IMG / IMM / APP / APG / APM products
Elevation gain calculated from the calibration pulses filtering based on difference with reference replica energy values
Dependency of the reference replica energy values with polarization
Solution to the stripline products Doppler estimates on the last slice of the product
Solution to minor anomalies in the annotations GM inverse filter verification Introduction of the scene altitude over WGS 84 to perform
geometry calculations: Effects of incorrect antenna pattern correction can be noticed on high terrain areas
Page 18ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Open Issues – Future Development (2) Altitude information needs to be passed to the processor to avoid
radiometric errors
Page 19ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Conclusions Processor installed on the PDS generating ALL Level 1b and
Level 2 products with expected quality Minor algorithmic and operational problems solved during the
Commissioning Phase period Internal calibration procedure has been updated to avoid most
of calibration pulse artefacts: additional filtering is required All ASAR products normalized with the equivalent chirp energy
calculated from internal calibration except for AP where cal pulses are corrupted: use of reference values
Processing parameters have been updated to accommodate instrument bandwidth changes in IM/AP/WS products and improve product quality
Page 20ENVISAT Cal/Val Workshop – ESRIN – 9/13 December
2002
Conclusions
Auxiliary files have been updated with the latest antenna patterns and instrument characterization parameters
Minor modifications will be added to the processor in order to improve product quality (ENL & SNR) and avoid radiometric errors over high terrain areas