The Data Processing Unit of the Solar Wind Analyzer SWA onboard Solar Orbiter
The Data Processing Unit of the Solar Wind Analyzer SWA onboard Solar Orbiter
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太阳轨道飞行器上太阳风分析仪 SWA 的数据处理单元
DOI：
10.1002/essoar.10501320.1
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Bruno R
中科院分区：
文献类型：
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作者：
Bruno R
数据处理单元（DPU）是血浆套件SWA的“心脏”，是与S/C的唯一接口。DPU通过SpW专用链路与EAS、PAS和HIS传感器连接，并负责支持EAS和PAS的电源、功能控制、临时存储、通信和计算能力，此外，还支持HIS与S/C的通信。它的架构来自一个权衡分析，旨在定义一个系统，能够执行所需的计算任务，同时保持质量，体积和功率的限制内的约束。此外，DPU被设计为“单一故障”容错，“冷备用”概念被采纳为冗余原理。它通过冗余SpaceWire（SpW）数据链路和冗余电源输入HV-HPC命令接口实现与S/C的数据和命令接口。两个独立的可执行软件映像代表整个SWA DPU软件：靴子软件（BSW）和飞行软件（FSW）。BSW管理基本硬件初始化，FSW管理TC/TM，控制与传感器状态相关的所有过程，验证和执行TC，在EAS（1和2）和PAS传感器下行链路之前获取、处理、压缩和格式化科学数据，而HIS自主处理其科学数据。特别是，FSW负责数据压缩、力矩计算和遥测生成限制，以使每个传感器保持在其各自的遥测分配范围内。EAS的数据压缩，产生最大的数据量，达到了显着的水平，通过定制实现无损CCSDS 121.0的基础上的“复杂的重新排序”机制，避免了周期性的相位空间中的采集方向之间的跳跃。质子和电子的速度分布函数的时刻计算板载。用于PAS和EAS的不同查找表（LUT）允许通过这些表中包含的因子的组合来执行调制相空间的每个体积中的计数的矩计算。最后，由于SWA数据产生从正常模式到突发模式发生了很大变化，因此簿记算法（BKA）将沿着轨道连续地沿着监视和控制突发模式的量，所述突发模式的量是针对按比例的期望而被调度或触发的。
The Data Processing Unit (DPU) is the “heart” of the plasma suite SWA and is the only interface with the S/C. The DPU is interfaced with EAS, PAS and HIS sensors via SpW dedicated links and is in charge of supporting EAS and PAS with power, functionality control, temporary storage, communication and computational capability and, in addition, supports HIS with communication to the S/C. Its architecture derives from a trade-off analysis aiming to define a system able to perform the needed computational tasks while keeping mass, volume and power within the limits imposed by the constraints. Additionally, the DPU has been designed to be “single fault” tolerant and the “cold-spare” concept has been adopted as redundancy philosophy. It implements data and command interfaces with the S/C via the redundant SpaceWire (SpW) data links and the redundant power input HV-HPC command interface. Two independent, executable SW images represent the overall SWA DPU SW: the Boot SW (BSW) and the Flight SW (FSW). While the BSW manages the basic hardware initialization, the FSW manages TC/TM, controls all the processes related to the state of the sensors, validates and executes TC, acquires, processes, compresses and formats science data prior to downlink for EAS(1&2) and PAS sensors, while HIS autonomously processes its scientific data. In particular, FSW is in charge of data compression, moments calculation and telemetry generation restrictions to keep each sensor within its respective telemetry allocation. Remarkable level of data compression for EAS, which generates the largest data volume, is reached via customized implementation of lossless CCSDS 121.0 based on a “Complex Reordering” mechanism, which avoids periodical jumps among acquisition directions in phase space. Moments of proton and electron velocity distribution functions are computed onboard. Different Look-Up Tables (LUT) for PAS and EAS allow to perform moments calculation modulating the counts in each volume of phase space by a combination of the factors contained in these tables. Finally, since SWA data production greatly changes from normal to burst mode, a book keeping algorithm (BKA) will monitor and control, continuously along the orbit, the amount of burst mode, scheduled or triggered, used against the pro-rata expectation.