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ENVISAT Commissioning Phase Review: PF-ASAR Status

ENVISAT Commissioning Phase Review: PF-ASAR Status. PF-ASAR Processor Releases PF-ASAR in PDS vs. Stand-alone PF-ASAR PF-ASAR Changes Since ENVISAT Launch PF-ASAR Unresolved Issues. PF-ASAR v2.13, February 11, 2002 (last release before ENVISAT launch) PF-ASAR v2.14, April 17, 2002

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ENVISAT Commissioning Phase Review: PF-ASAR Status

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  1. ENVISAT Commissioning Phase Review: PF-ASAR Status • PF-ASAR Processor Releases • PF-ASAR in PDS vs. Stand-alone PF-ASAR • PF-ASAR Changes Since ENVISAT Launch • PF-ASAR Unresolved Issues

  2. PF-ASAR v2.13, February 11, 2002 (last release before ENVISAT launch) PF-ASAR v2.14, April 17, 2002 PF-ASAR v2.14.01, May 7, 2002 (parameter updates only) PF-ASAR v2.14.02, May 17, 2002 PF-ASAR v3.00, August 9, 2002 (new BAQD decoder tool binaries also released) PF-ASAR v3.01, August 30, 2002 Another release is anticipated in the near future for Wave Level 2 algorithm updates All releases included both PF-ASAR for PDS and Stand-Alone PF-ASAR/ERS for debugging/testing PF-ASAR Processor Releases

  3. Two versions of PF-ASAR are being supported with each release, both of which use the same core processor but operate within different contexts PF-ASAR in PDS vs. Stand-alone PF-ASAR “Integrated” PF-ASAR within ENVISAT PDS “Stand-alone” PF-ASAR for testing and debugging outside ENVISAT PDS

  4. Internal calibration handling Processor modifications Medium resolution to browse LUT Descalloping enable/disable flag Doppler refinement enable/disable flag GM range inverse filter New geocoding options Parameter updates New Wave Level 2 algorithm PF-ASAR Changes Since ENVISAT Launch

  5. Modified preprocessing to handle Wave Mode case where the chirp calibration packet is missing but the CW packet is still available Added support for extracting calibration packets for chirp reconstruction outside the limits of data to be processed, if available Added threshold check for reconstructed replica spikes at high and low frequencies Internal Calibration Handling

  6. Internal Calibration Handling (cont.) Without correction With correction

  7. Added individual calibration pulse amplitude check and correction Internal Calibration Handling (cont.) Without correction With correction

  8. Added phase unwrapping step for phase average calculation for Wave Mode calibration Internal Calibration Handling (cont.)

  9. Medium resolution to browse LUT Processor Modifications • Added a look-up table and gain factor to be used when converting all medium resolution products to browse • One LUT and gain for all products • Current table has only 11 points for incidence angles between 10 and 50 degrees

  10. Descalloping enable/disable flag Option added to disable application of descalloping function in Specan by applying a flat antenna pattern Descalloping is currently turned off by default Doppler refinement enable/disable flag Option was added to turn doppler refinement off (without the proper azimuth antenna patterns, refinement was not improving the doppler estimates) GM Inverse Filter Specan option enabled for processing GM data Processor Modifications (cont.)

  11. New geocoding options By default, PF-ASAR uses kernel interpolation for geocoding Option to perform linear correction of dark pixels around point targets added Option to perform 2D bi-linear interpolation also added Processor Modifications (cont.) Kernel Interpolation Kernel Interpolation with Linear Correction Bi-linear Interpolation

  12. Beam/swath-dependant processing gain support added for all products/modes Gains have been set for all IM, WS and WV products. These were set based on transponder analysis to ensure products would not saturate in any beam. AP gains also set based on IM Gains for all IM and WV beams currently set to the same value, but could be adjusted in the future WS processor gains vary from swath to swath Parameter Updates

  13. Replica energy reference energy levels set for all IM, WV and WS beams Some processing parameter changes, particularly for new WS settings (range look bandwidth increased, number of looks increased from 3 to 7) Parameter Updates (cont.)

  14. New Wave Level 2 algorithm based on version 2.2.5 of the Software Requirements Document provided by NORUT added to PF-ASAR Wave Mode processor Wave L2 Ocean Wave Spectra created in parallel to Wave L1 Cross Spectra whenever Wave L1 Imagette processing is performed Initial verification of algorithm implementation has been done by comparing one ERS-2 and one ASAR IS2 reference acquisition processed by PF-ASAR with output produced by IDL prototype processor Some differences identified that still need to be resolved - SRD v2.2.7 just released with some algorithm updates which should already be in PF-ASAR New Wave Level 2 Algorithm

  15. Strong scatterer processing artifact In IM medium-resolution products processed by PF-ASAR, a range artifact has been observed around strong targets in some scenes Preliminary analysis indicates this is related to the range multi-looking stage of the Specan processor and the size of the FFT being used. Experiments with different FFT lengths and processing block sizes appear to eliminate the artifact. Additional analysis will be done to understand the problem and make the appropriate fix. PF-ASAR Unresolved Issues

  16. Wave Level 2 Algorithm updates are anticipated based on further investigation into differences between PF-ASAR and IDL prototype Wave Level 1 Spectra noise has been introduced during Wave Level 2 processor development that is under investigation More parameters changes Switch from Extracted to Nominal chirp for all modes Elevation angles for Stripline products still need to be set System offset frequencies for single-beam doppler ambiguity estimation System gains for AP and GM modes Minor software issues PF-ASAR Unresolved Issues (cont.)

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