20
Page 1 ENVISAT 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 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status Processor releases Internal calibration updates Processing

Embed Size (px)

Citation preview

Page 1: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 2: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 3: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 4: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 5: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 6: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 7: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 8: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 9: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 10: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 11: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 12: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 13: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 14: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 15: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 16: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 17: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 18: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 19: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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 20: Page 1ENVISAT Cal/Val Workshop – ESRIN – 9/13 December 2002 ASAR Processing Facility Status  Processor releases  Internal calibration updates  Processing

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