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ASAR IMAGE MODE MEDIUM RESOLUTION PRODUCT STATUS

ASAR IMAGE MODE MEDIUM RESOLUTION PRODUCT STATUS. Nominal Product Characteristics Image Quality Characterization Open Quality Issues Conclusions. Josep Closa ESA - ESRIN. Ground range projected detected products Nominal resolution < 150 m Pixel spacing 75 m ENL > 30

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ASAR IMAGE MODE MEDIUM RESOLUTION PRODUCT STATUS

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  1. ASAR IMAGE MODE MEDIUM RESOLUTION PRODUCT STATUS • Nominal Product Characteristics • Image Quality Characterization • Open Quality Issues • Conclusions Josep Closa ESA - ESRIN

  2. Ground range projected detected products Nominal resolution < 150 m Pixel spacing 75 m ENL > 30 8 looks in azimuth, 4 looks in range 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 Product size: multiple of granule interval (1.5 seconds) Innovative ground range projection to keep constant incidence angle at the center of the product (common to all stripline products) IMM PRODUCT NOMINAL SPECIFICATION

  3. IMM PRODUCT FROM ORBIT 1987 – IS6 - VV polarization

  4. IMM SLANT TO GROUND PROJECTION

  5. IRF quality analysis performed only using ESA transponders Only VV polarization Products processed with latest processor version and updated elevation patterns IRF MEASUREMENTS

  6. Range Resolution match expected theoretical values for all beams Theoretical values ranging from 107 m (far range IS1) to 160 m (near range IS1) Range resolution > 150 m for near range of IS1 but within requirements (10 % degradation) IRF RANGE RESOLUTION

  7. PF-ASAR automatically selects the number of range lines to achieve the required Doppler bandwidth Azimuth resolution within the requirements (10 % degradation) for all beams IMM AZIMUTH RESOLUTION

  8. PSLR AND ISLR MEASURENTS • Range PSLR = -16.7 dB Std Dev = 1.9 Theoretical value: -21.2 dB • Azimuth PSLR = -19.1 dB Std Dev = 1.0 Theoretical value: -20.5 dB • ISLR > requirements on high percentage of cases due to energy from the background

  9. Calibration constant derived from ESA transponder measurements Some outliers not taken into account in the calculation Different calibration constants for each swath (~0.6 dB) could be compensated in the processor by changing the processing gains More acquisitions needed to establish a stable calibration constant CALIBRATION CONSTANT AND RADIOMETRIC STABILITY

  10. Measurements performed for all swaths on acquisitions over the rainforest Values within the requirements (30 – 3%) for all the beams EQUIVALENT NUMBER OF LOOKS AND RADIOMETRIC RESOLUTION

  11. Noise measured on dark areas from several swaths from the acquisitions over the ESA transponders Values calculated using the derived IMM calibration constant from the transponders consistent with measurements on other product types NOISE EQUIVALENT SIGMA NOUGHT

  12. IMM products are processed using the Specan algorithm (data is treated as burst mode data): Remote possibility of scalloping Scalloping detected occasionally on certain beams generally over sea areas Scalloping usually due to inaccurate azimuth antenna patterns in the auxiliary files (update ongoing) and in very few cases to Doppler treatment in the processor Processing parameter to be changed in new PF-ASAR version to not apply a descalloping function OPEN ISSUES: SCALLOPING

  13. Effect detected occasionally on some strong targets and only on IMM products Degradation affects only the response in range Effect due to ground processing: under investigation OPEN ISSUES: IRF DEGRADATION ON SOME STRONG TARGETS

  14. Pre-validation of the IMM products done for all IM beams finished All IRF measurements as expected: Difficulty to measure the ISLR due to low resolution All quality measurements within the expected values Initial value for the calibration constant derived Some open quality issues affecting very small number of products under investigation CONCLUSIONS

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