GSC Sentinel-2 PDGS OCD - Emits - ESA

GSC Sentinel-2 PDGS OCD
Issue 1 Revision 2 (draft) - 25.07.2010
GMES-GSEG-EOPG-TN-09-0008
page 196 of 350
○ a system-level functionality expected to be translated into an automated behaviour of
the PDGS through actual systems but which is intentionally left at system-level to
maximise the opportunity of fulfilling it by reusing aggregate or customisable existing
solutions;
5.2 Functional Model
This section describes the decomposition of the PDGS overall functionality into
complementary high-level primary Functions.
5.2.1 DESIGN LOGIC
Based on the overall design rationale presented in the previous paragraph, the functional
decomposition aims at defining a logical split of the PDGS overall required functionality into
primary Functions which can optimally be distributed across centres to globally implement the
operation baseline of the PDGS. As such, the functional breakdown comprehensively aims at:
○ Providing a first-level layout of primary Functions each one solving part of the problem
in coordination with others in a logical way;
○ Providing a clear basis for the definition of operation concepts at Function-level that
logically aggregate at system-level in responding to the PDGS baseline services;
○ Isolating Functions in view of optimising the logical-to-physical mapping into macrofunctional
roles for the definition of PDGS Centres;
○ Isolating Functions according to typical existing market solutions that can be reused in
parts or entirely from previous PDGS developments, while concentrating the
specificities of the Sentinel-2 PDGS into other dedicated Functions;
○ Providing a clear view over the envisaged enhancements compared to previous
developments, to meet the particular challenges of the Sentinel-2 mission;
○ Ensuring the functional blocks can be clearly associated to their key design-drivers in
view of their implementation;
○ Embedding the required flexibility and scalability in the design in view of the distributed
but yet unknown physical layout of the PDGS;
Following a first section defining the breakdown, each identified function is then separately
detailed with its specific objective, design-drivers and logical interfaces to the other functional
blocks. The design rationale pertinent to each function group or function is described recalling
the source operation constraints and drivers of section 4.3. Specific relevance to the PDGS
operation baseline definitions outlined in chapter 4 is also pointed out.
5.2.2 FUNCTIONAL BREAKDOWN
The first-level of the PDGS functional decomposition discriminates between Data
Management functions, System Control functions and Data-Communication functions.
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