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IM and WS Mode Level 1 Product quality update

IM and WS Mode Level 1 Product quality update. Introduction IM Mode Optimisation Updated IMS product quality (VV & HH) Updated IMP product quality (VV & HH) Updated IMM product quality (VV & HH) Updated WSM product quality (VV & HH) Conclusions. B. Rosich ESA/ESRIN.

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IM and WS Mode Level 1 Product quality update

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  1. IM and WS Mode Level 1 Product quality update Introduction IM Mode Optimisation Updated IMS product quality (VV & HH) Updated IMP product quality (VV & HH) Updated IMM product quality (VV & HH) Updated WSM product quality (VV & HH) Conclusions B. Rosich ESA/ESRIN

  2. IM Mode products characterised and preliminary calibrated at the ECR (September) for VV polarisation. IM Mode optimisation peformed in October requires a revision of the product quality. Characterisation of HH polarisation also needed. Very prelimianry verification of WSM products at the ECR for VV polsarisation. An additional change in the mode requires revision of product quality. Characterisation of HH polarisation also needed. Introduction

  3. IM mode optimisation at instrument level - Increase the Tx. Chirp BW to 16 MHz for all swaths (17-10-02): IM mode optimisation at processing level - Depends on product type IM Mode Optimisation

  4. 1751, IS1 ASAR IMS Product charateristics • Slant range, single look complex image. • Single polarisation VV or HH. Multiple incidence angles (IS1 to IS7). Coverage from 100 Km to 56 km • Natural pixel spacing in range and azimuth. Azimuth resolution from 4 m to 5 m.Range resolution from 9 m to 18 m due to decreasing chirp bandwidth. • Elevation antenna pattern correction not applied. Range spreading loss correction not applied. • Hamming window with a=0.75 applied in azimuth and range • Processing algorithm: Range Doppler. Phase preserving.

  5. Range Processing: Full BW processed for all beams. Constant slant range resolution from IS1 to IS7. Change of processing settings & products characteristics for IMS products Change in quality requirements for IMS products.

  6. Azimuth processing: No changes. Gain settings: No changes. Complete Tx. BW used before/after the BW change. No changes in the processor gain. Same K as for data acquired before the BW change. IMS Absolute Calibration update

  7. IMS Product quality vs. time & vs. PF-ASAR version

  8. IMS HH Ambiguities Visible az. Ambigities for HH products - Distributed target ambig. ratio: -25.5 dB (IS5), -24 (IS4) Point target ambiguity ratio: ~-26 dB Ambiguity ratio requirement is –25 dB. Migth be too high for HH products over low backscattering areas.

  9. Properties of IMP Products • Ground range detected imagery • Single polarisation (VV or HH) • Elevation antenna pattern and range spreading loss corrections applied • Size of up to 150Mbytes with 2 byte (16bit) amplitude pixel values • Swath widths of 100 km (IS1) to 56 km (IS7) with azimuth extents of ~100 km • Azimuth resolution of 20.7m (4 looks of 320 Hz) • Range resolution from 21m (IS2 far range) to 37m (IS1 near range) and ~26m for IS3 to IS7 • 12.5m by 12.5m pixels

  10. Change of processing settings & product characteristics for IMP products Azimuth processing: - No changes. Same number of looks (4) and same look BW. Range Processing: • Range look BW: same as before, i.e. same range resolution • Number of range looks: same as before (1). Increase in noise level expected for the higher inc. ang. beams. Gain settings: • Gain adjusted to compensate the fact that the full Tx. BW is only partially processed. • Same K as for data acquired before the BW change.

  11. IMP Range resolution Measurements demonstrate that there is no change in range resolution and values are well within the requirements for VV & HH

  12. IMP Absolute Calibration Measurements demonstrate that the same absolute calibration factor applies for data acquired before and after the BW change.

  13. IMP Azimuth resolution, ISLR, PSLR • Values are within the requirements • High PSLR observed however in few cases

  14. IMP Product quality vs. time & vs. PF-ASAR version

  15. Clear Az. Ambiguities on HH products, over low backscattering areas. Amb.ratio: -25.8 (IS5) -21.1 (IS4) 3354, IS5, 4 looks 3354, IS5, 2 looks IMP HH Az. Ambiguities Processing only 2 looks in az.: Amb.ratio: -28 dB (IS5)

  16. IMMProduct Characteristics • Ground range projected detected products • Nominal resolution < 150 m . Pixel spacing 75 m • 8 looks in azimuth, 4 looks in range. ENL > 30 • Antenna pattern and range spreading loss correction applied • Data output as unsigned 16 bit • Systematic stripline processing: products as long as the complete acquisition segment • Innovative ground range projection to keep constant incidence angle at the center of the product (common to all stripline products)

  17. Range Processing: Range look BW: same as before, i.e. same range resolution Number of range looks: 10 (5 before). ENL increase expected. Look overlap different for different beams. Different ENL expected. Change of processing settings & products characteristics for IMM products Azimuth processing: - No changes. Same number of looks (8) and same look BW.

  18. IMM ENL • Measurements not available yet for all swaths. • No changes expected for IS1 and IS2. • For the beams with very small look overlap, values up to 80 looks are achieved • Initial requirement for IMM ENL was 30 looks. • Only negative impact is throughput Change in quality requirements needed.

  19. IMM Spatial Resolution • Range & Azimuth Resolution match expected theoretical values for all beams • Theoretical values ranging from 107 m (far range IS1) to 160 m (near range IS1)

  20. IMM Absolute calibration No changes in processing gain. Changes in product level expected between data acquired before/after the BW change. Change of K between products with original Tx. Chirp BW and products with new full TX. Chirp BW.

  21. IMM Product quality vs. time & vs. PF-ASAR version

  22. 3354 ,IS5, HH, 4 looks 3397,IS4, HH 3354 ,IS5, HH IMM HH Az. Ambiguities • Visible Az. Ambiguities for HH products: • Distributed target ambig. ratio: ~-20 dB • IMM reprocessing using 4 rather than 8 looks in azimuth: • Amb. Ratio: - 24.5 dB

  23. WSM Product characteristics • Ground range projected detected products • Nominal resolution < 150 m • Swath width: 406 Km • Pixel spacing 75 m • ENL > 12 for all the different subswaths • Antenna pattern and range spreading loss correction applied • Data output as unsigned 16 bit • Systematic stripline processing: products as long as the complete acquisition segment

  24. Initial instrument settings (till 13-08-02) Tx.Chirp BW: Mode timeline (pulses per burst): SS1-SS5: 50, 80, 67, 87, 74 Initial processing/product settings (version < 3.01): Rg. Look BW: Number of range looks: 3 WSM Initial product quality • Result: • - Range resolution ~ 150 m and Azimimuth resolution ~90 m • - ENL: below the requirements (12) -> from 8 for SS1 to 6 for SS5

  25. First mode optimisation at instrument level (13-08-02): IncreaseTx.Chirp BW: New processing/product settings (version >= 3.01): • Rg. Look BW: • Number of range looks: 7 First WSM optimisation (I)

  26. First WSM optimisation (II) • Result: • Range resolution: ~ 120 m • Azimimuth resolution: ~90 m -> High undersampling & not-square resolution • ENL: higher than initial spec (12) • Inter-burst ambiguities (~-21 dB) detected in high contrast scenes (already present before the BW change)

  27. Second WSM optimisation Second WS mode optimisation at instrument level (30-10-02) • Change of mode timeline (expect SS1): SS1-SS5: 50, 65, 55, 71, 60 New processing settings: • None. Only AUX data updated Result: • Removal of inter-burst ambiguities • Increase of Az. Res. WSM 2703

  28. WSM Final products resolution • Nominal products are still undersampled: 1.2 in range, 1.4 in azimuth. • Resolution is almost square. Could be adjusted to be more similar in both directions. • IRF measurements performed on oversampled products of 40x40 m.

  29. WSM Absolute calibration update K (VV) from rain forest: 69.08 dB

  30. Noise level for SS1 expected to be higher than for the other swaths. Measured values for final settings: SS1: ~-22 dB SS2-SS5: ~-24,-25 dB The difference in noise level between SS1 and SS2 is clearly visible in the images. WSM Noise Equivalents0 SS1 SS2

  31. IM mode BW increase has resulted in an improved IMS and IMM product quality and will increase the IM InSAR performance. Products quality shall be now stable. The BW increase shall be almost transparent for IMP products. Quality could be improved with multi-look in range. WSM optimizations provide very good product quality. Products should be now stable. Quality results for HH polarisation are equivalent to those for VV polarisation. Conclusions

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