40 Gbps data acquisition system for NectarCAM
40 Gbps data acquisition system for NectarCAM
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适用于 NectarCAM 的 40 Gbps 数据采集系统
DOI：
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发表时间：
2017
期刊：
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通讯作者：
J. Houles
中科院分区：
文献类型：
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作者：
D. Hoffmann;J. Houles
切伦科夫望远镜阵列(CTA)将是下一代地面伽马射线天文台。它将由大约100个直径从4米到23米的三种不同大小的望远镜组成。先前提出的用于CTA的高速数据采集(DAQ)系统的原型(CHEP 2012，[6])已在NectarCAM项目中具体化，该项目是最具挑战性的相机项目之一，对数据处理的带宽要求非常高。我们设计了一个Linux-PC系统，能够集中和处理来自265个前端板卡(FEB)的40 GB/S平均数据速率，通过千兆以太网链路，并通过外部触发判决和定制的压缩算法来减少数据以适应两条万兆以太网下行链路。在给定的限制范围内，我们使用项目所需的现成设备，在至少30年的运行期内，对FEB发出的相对较小的UDP包接收的事件片段进行去随机化。我们测试了开箱即用的接口，并使用了独创的技术来满足这些要求，并建立了带有数百条同步千兆链路的测试台，以验证和调整采集链，包括基于zeroMQ和Google ProtocolBuffers的下行数据记录[8]。
The Cherenkov Telescope Array (CTA) will be the next generation ground-based gamma-ray observatory. It will be made up of approximately 100 telescopes of three different sizes, from 4 to 23 meters in diameter. The previously presented prototype of a high speed data acquisition (DAQ) system for CTA (CHEP 2012, [6]) has become concrete within the NectarCAM project, one of the most challenging camera projects with very demanding needs for bandwidth of data handling. We designed a Linux-PC system able to concentrate and process without packet loss the 40 Gb/s average data rate coming from the 265 Front End Boards (FEB) through Gigabit Ethernet links, and to reduce data to fit the two ten-Gigabit Ethernet downstream links by external trigger decisions as well as custom tailored compression algorithms. Within the given constraints, we implemented de-randomisation of the event fragments received as relatively small UDP packets emitted by the FEB, using off-the-shelf equipment as required by the project and for an operation period of at least 30 years. We tested out-of-the-box interfaces and used original techniques to cope with these requirements, and set up a test bench with hundreds of synchronous Gigabit links in order to validate and tune the acquisition chain including downstream data logging based on zeroMQ and Google ProtocolBuffers [8].