GSC Sentinel-2 PDGS STBD - emits - ESA

More documents

Recommendations

Info

GSC Sentinel-2 PDGS STBDIssue 1 Revision 2 (draft) - 25.07.2010GMES-GSEG-EOPG-TN-09-0031page 35 of 603.4.2 PROCESSING RESOURCES ESTIMATIONThe processing activities of only one satellite are considered.The budget estimations consist in an evaluation of number of needed resources allowing torespect the delivery time constraints defined in section 3.4.2, according to the benchmarks(cf. Section 3.2) and the parallelisation opportunities of each Processing Step (recalled inSection 3.3). Assuming a linear scalability of the performance with the hardware as justifiedin 3.3.3, the number of resources (in CPU-units) will be computed as:Resources = (Scaled Benchmark time / Timeliness constraints) + Margins (%)With the following timeliness constraints: Front-End Processing: T FE = downlink-time Bulk-Processing: T BP = 100 minutesAssuming a linear relationship with the data volumes, the Reference Benchmark timeswill be scaled from the reference times by the actual volume of data to be processed withrespect to the reference datastrip volume of 57Gbytes.3.4.3 RE-PROCESSING RESOURCES ESTIMATIONThe estimation of the number of CPUs dedicated to re-processing has been made under theassumption that the data corresponding to X time shall be reprocessed up to Level-1C in 2times X (e.g. 2 months to re-process 1 month of data).Re-processing is based on the Level-0 data already processed, consolidated and archivedthen there is no need to allocate computing resources to the Level-0 processing.3.4.4 PROCESSING RESOURCES ESTIMATION WITH BOTH SATELLITESIn the previous paragraphs only the data acquired and downlinked by one satellite havebeen considered for the estimations.When both satellites will be operational, the computing resources shall be doubled to facethe doubled data volume except if some optimization in the processing time management isfound.The rationale of this scenario is fundamentally equal to Scenario 0 - one centre receivingand processing the entire amount of data, no difference between RT, NRT and Nominal dataprocessing time - but both satellites are considered and slight differences therefore arise.One satellite has an orbit period of 100 minutes.The second satellite will follow the same orbit of the first satellite with a constant phasing of180° (as showed in figure 13), i.e. 50 minutes of delay.In terms of imaging/downlink cycle, the combination of this 180° phase difference on theorbit and Earth rotation. This allows reaching the 5 days of repetitively required by themission.ESA UNCLASSIFIED – For Official Use© ESAThe copyright of this document is the property of ESA. It is supplied in confidence and shall not be reproduced, copied orcommunicated to any third party without written permission from ESA.
GSC Sentinel-2 PDGS STBDIssue 1 Revision 2 (draft) - 25.07.2010GMES-GSEG-EOPG-TN-09-0031page 36 of 60Figure 13: Sentinel-2A and Sentinel-2BIt is then assumed that data downlink will take place with 50 minutes of difference.The following rationale is adopted.Sentinel-2A downlinks on board data to the unique station at first.If all Sentinel-2A data are processed in 50 minutes, when Sentinel-2B transmits its on boarddata, the CPUs of the station will have completed S2A data processing and will be availableto process Sentinel-2B data.As shown by the chronogram of the following figure, the timeliness of the end-to-endproduction for each satellite will be lowered by 50 minutes.S2Adownlink20 min40 minS2Bdownlink60 min80 minS2Adownlink100 min120 minX CPUL0 generation (S2A)L0 generation (S2B)L0 generation (S2A)Y CPUL0 consolidation + L1 processing (S2A)L0 consolidation + L1 processing (S2B)Figure 14: Chronogram of the Scenario with 2 satellites3.4.5 SCENARIO-0 BUDGET ESTIMATIONS3.4.5.1 AssumptionsIn this simplified scenario, the resources necessary to globally process all the data areestimated assuming a simple and ideal case where all data were received and processed inone unique centre.Although not a realistic scenario, it has been considered to describe the rationale andprovide preliminary processing budget estimates.It assumes a regular pattern of data downlinks occurring once per orbit, each onecorresponding to the recovery on-ground of an average MSI datastrip identical to the oneESA UNCLASSIFIED – For Official Use© ESAThe copyright of this document is the property of ESA. It is supplied in confidence and shall not be reproduced, copied orcommunicated to any third party without written permission from ESA.
Page 2 and 3: GSC Sentinel-2 PDGS STBDIssue 1 Rev
Page 13 and 14: - (A 1 - D 1 ) ≤ 100 minutes, i.e
Page 27 and 28: 3.3.2 ANALYSIS OF PARALLELISATION O
Page 39: GSC Sentinel-2 PDGS STBDIssue 1 Rev
Page 59: GSC Sentinel-2 PDGS STBDIssue 1 Rev

GSC Sentinel-2 PDGS STBD - emits - ESA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?