A Simulation Tool for Payload Data Volume & Downlink Latency Estimation in Leo Earth Observation Satellite
- Paper number
IAC-08.B1.4.7
- Author
Mr. Mario Cossu, ThalesAlenia Space Italia S.p.A., Italy
- Coauthor
Dr. Michelangelo L'Abbate, Thales Alenia Space Italy, Italy
- Coauthor
Dr. Paolo Venditti, Thales Alenia Space Italy, Italy
- Coauthor
Dr. Adriano Lupi, Thales Alenia Space Italy, Italy
- Coauthor
Dr. Roberto Sigismondi, Thales Alenia Space Italy, Italy
- Coauthor
Dr. Ugo Pattacini, Thales Alenia Space Italy, Italy
- Year
2008
- Abstract
In Earth Observation Satellites, Thales Alenia Space Italia (TASI) indicates with the acronym PDHT (Payload Data Handling & Transmission) the unit aimed to acquisition, storage and formatting of scientific data provided by embarked measurement instruments (i.e. SAR, Optical, etc…) and the transmission to ground stations. As part of this payload, DSHA (Data Storage & Handling Assembly) is deputed to the instrument interface, the data storage and the subsequent formatting and forward to modulation and amplification section. Following the increasing request of high resolution images, near real time acquisitions and data time-lines requirements, DSHA memory sizing and throughput is becoming a very crucial task that shall take into account both stringent mission requirements and technological constraints. A simulation tool called DESOS (Data Exchange Simulator in Orbital Scenarios) was recently conceived in TASI to carry out this challenging trade-off activity, and in particular to verify the capability to store a maximum number of images per orbit and downlink them within an acceptable timelines, avoiding at the same time a “Memory full” status. DESOS is implemented in the MATLAB environment as a Simulink model exploiting the powerful capabilities of SimEvents blockset, which permits system's state transitions to depend on asynchronous discrete incidents that are called ‘events’. SimEvents enables the development of activity-based models to evaluate system parameters such as congestion, resource contention, and processing delays. DESOS uses data from STK or internal developed Mission Simulator as input for a given orbital cycle, allowing a customizable scenario in terms of data acquisition time-line and ground station number & location; it computes the dynamic of the on-board memory occupancy throughout the entire orbital cycle, simulating the memory data flux between data acquisition (filling) and transmission to Ground (emptying), considering as ‘event’ each data packet passing through the memory and the transmission assembly. Although the memory is internally organized as FIFO, a priority flag can be given to input data to simulate the presence of near real time data; hence, events’ transmission is simulated following a set of rules depending on acquisition modes (e.g. FIFO based or in near real time data), downlink data rates, data compression ratio and other more parameters selectable through a graphical user interface. At the end of a simulation, a set of statistics is provided, showing the capability of the simulated system in terms of data downlink latency and maximum on-board memory capacity expected during the orbital cycle.
- Abstract document
- Manuscript document
IAC-08.B1.4.7.pdf (🔒 authorized access only).
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