The LOFAR Beam Former: Implementation and Performance Analysis
The LOFAR Beam Former: Implementation and Performance Analysis
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LOFAR 波束形成器：实施和性能分析
DOI：
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发表时间：
2011
期刊：
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通讯作者：
J. Romein
中科院分区：
文献类型：
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作者：
J. Mol;J. Romein
传统的射电望远镜使用大型的钢制碟形天线来观测射电源。LOFAR射电望远镜是不同的，它使用了成千上万个固定的、不可移动的天线，这是一种新颖的设计，有望在天文学领域进行开创性的研究。这些天线进行全方位的观测，而天空中的源则通过信号处理技术进行观测，该技术将来自所有天线的数据进行联合收割机组合。
LOFAR的另一个新功能是精心使用软件来进行真实的信号处理，而传统望远镜使用定制的硬件。软件的使用使仪器本身更加灵活。然而，巨大的数据速率（198 Gb/s的输入数据）和处理要求迫使使用超级计算机：我们使用IBM Blue Gene/P。
本文介绍了一系列新的处理管道，统称为波束形成管道，大大提高了望远镜的功能。我们的第一条管道只能关联数据来创建天空图像，新的管道允许发现未知的恒星，观测已知的恒星，并（在未来）观测宇宙射线和研究瞬态事件。与传统望远镜不同，我们可以同时从数百个方向进行观察。这是有用的，例如，搜索天空中的新恒星。软件的使用使我们能够快速添加新功能，并适应新的见解，充分利用我们独特仪器的新颖功能和强大功能。我们还描述了我们的优化，以非常高的效率使用蓝色基因/P，最大限度地提高整个望远镜的有效性。全面的性能研究确定了我们系统的局限性。
Traditional radio telescopes use large, steel dishes to observe radio sources. The LOFAR radio telescope is different, and uses tens of thousands of fixed, non-movable antennas instead, a novel design that promises groundbreaking research in astronomy. The antennas observe omnidirectionally, and sky sources are observed by signal-processing techniques that combine the data from all antennas.
Another new feature of LOFAR is the elaborate use of software to do signal processing in real time, where traditional telescopes use custom-built hardware. The use of software leads to an instrument that is inherently more flexible. However, the enormous data rate (198 Gb/s of input data) and processing requirements compel the use of a supercomputer: we use an IBM Blue Gene/P.
This paper presents a collection of new processing pipelines, collectively called the beam-forming pipelines, that greatly enhance the functionality of the telescope. Where our first pipeline could only correlate data to create sky images, the new pipelines allow the discovery of unknown pulsars, observations of known pulsars, and (in the future), to observe cosmic rays and study transient events. Unlike traditional telescopes, we can observe in hundreds of directions simultaneously. This is useful, for example, to search the sky for new pulsars. The use of software allows us to quickly add new functionality and to adapt to new insights that fully exploit the novel features and the power of our unique instrument. We also describe our optimisations to use the Blue Gene/P at very high efficiencies, maximising the effectiveness of the entire telescope. A thorough performance study identifies the limits of our system.