1 / 20

GOCE L1b processing

GOCE L1b processing. Frommknecht, Bjoern 1 ; Stummer, Claudia 2 ; Gilles, Pascal 1 ; Floberghagen, Rune 1 ; Cesare, Stefano 3 ; Catastini, Giuseppe 3 ; Meloni, Marco 4 ; Bigazzi, Alberto 4 1 ESA/ESRIN (ITALY); 2 IAPG - TU Munich (GERMANY); 3 TAS-I (ITALY); 4 SERCO (ITALY).

sheila
Download Presentation

GOCE L1b processing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GOCE L1b processing Frommknecht, Bjoern 1; Stummer, Claudia 2; Gilles, Pascal 1; Floberghagen, Rune 1; Cesare, Stefano 3; Catastini, Giuseppe 3; Meloni, Marco 4; Bigazzi, Alberto 4 1ESA/ESRIN (ITALY); 2IAPG - TU Munich (GERMANY); 3TAS-I (ITALY); 4SERCO (ITALY)

  2. Telemetry (TLM) Extraction Level 0 Processing Level 1b Data levels

  3. Datation Angular Rate STR_VC2/3_1b EGG_NOM_1b SST_NOM_1b SST_RIN_1b Data types and products

  4. SSTI Data Processing • Conversion into engineering units • Correction of phase and code observations for instrument specific effects (IFB and ICB) • Corrected observations form RINEX product (SST_RIN_1b) • Nominal product contains position solution using only code observations (SST_NOM_1b) • Position solution used to derive correlation between OBT and GPS time • In case of single frequency measurements effect of Ionosphere is corrected using Ionosphere maps

  5. SSTI Data Processing • Positioning accuracy of several [m] sufficient for geolocation

  6. Star tracker processing • Conversion into engineering units • Transform datation from On Board Time to GPS time and UTC • Correction for orbital relativistic aberration (annual relativistic aberration is corrected on-board) • Resolve sign ambiguity to get continuous quaternion

  7. Gradiometer processing

  8. Depacketing • Apply calibration to transform into physical units • Transform datation from On Board Time to GPS time and UTC • Interpolate control voltages to star tracker measurement epochs

  9. Voltage to Accelerations

  10. Voltage to Accelerations • Correction of gain attenuation and phase delay of Science read-out branch (Butterworth anti-aliasing filter) and ADC • Electrode measurements recombination • Correction of gain attenuation and phase delay of the control loop and read-out function • Application of electrostatic gains • Generation of uncalibrated differential and common mode accelerations

  11. Calibration • Two parts • Gradiometer linearization (Proof mass shaking): Determination of quadratic factors + uplink of correction parameters • Relative calibration of accelerometer pairs (satellite shaking): Result is used in the nominal processing • See presentation: • The In-flight Calibration of the GOCE Gradiometer

  12. Calibration • Interaction between satellite and ground segment • Proof mass offset correction uplinked to satellite • Iterative process • Fast convergence

  13. Common and Differential Mode • Common and Differential Mode accelerations are formed by addition/subtraction of the individual linear accelerations per accelerometer and per axis • Multiplication with ICM delivers calibrated measurements • Calibrated Differential Mode accelerations deliver angular accelerations

  14. Angular Rate Reconstruction • Combination takes place on the level of angular rates • STR quaternions are converted into angular rate • Gradiometer derived angular accelerations are integrated • Additional parameters like acceleration low frequency noise and drifts are estimated as well

  15. Angular Rate Reconstruction • Results: • Angular Rate • Optimized attitude quaternion • Both data are available as Measurement Data Sets in the EGG_NOM_1b product • Angular Rate quality depends on used star tracker • Each filter reinitialisation ‘costs’ about 40 000 s of data

  16. Gravity Gradients • Gravity Gradients are formed by linear combination of Differential Mode accelerations and Angular Rate • Gravity Gradients are contained as a separate MDS in the EGG_NOM_1b product

  17. L1b processing status • Production is nominal and complete, no processing failures • Almost 7 months of L1b data generated • Nov and Dec 2009 released • Regular changes in Star Tracker that is used in the processing due to reconfiguration of the attitude control system

  18. L1b processing status STR 2 STR 1

  19. Define algorithms for star sensor fusion: ‘Virtual Star Tracker’ Update of existing Angular Rate Recovery processor for use of Virtual Star Tracker data Alternative Angular Rate and Attitude Recovery algorithm Way Forward

  20. Poster on PDGS architecture: GOCE Payload Data Ground Segment - Architecture and data access Poster on L1b Quality Control: Quality control of GOCE Level 1b data products L1b products description: http://earth.esa.int/GOCE

More Related