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Voytsekh Ken
Type of contribution: oral

IAA VGOS GPU-based software correlator: current status and broadband processing

Voytsekh Ken, IAA RAS Yana Kurdubova, IAA RAS Nadezda Mishina, IAA RAS Vladimir Mishin, IAA RAS Violet Shantyr, IAA RAS Igor Surkis, IAA RAS

The VGOS FX-type software correlator was designed in the IAA RAS. The correlator is able to process VDIF data from up to 6 stations simultaneously at a maximum rate of 16 Gb/s from each station. The main idea of the correlator design is the usage of Graphical Processing Units (GPUs) for fringe stopping, Fourier transformation, spectra multiplication and pcal extracting operations. The correlator hardware is based on a hybrid blade server cluster. Each blade server holds two Intel CPUs and two Tesla K20x GPUs. Usage of GPUs allows us to reduce the amount of blade servers required for such a high correlator performance. At present, the correlator cluster and the cooling system are almost assembled in the IAA. The cluster contains 4 compute racks with 8 cache and 40 blade servers, 80 TB data storage based on Panasas, and control servers. In order to test the six-station correlator in a maximal mode, an experiment was carried out with the following setup: 4 frequency channels each of 512 MHz bandwidth at 2 polarizations, 2-bit sampling. In each frequency channel 78 fringes were found. The first results of comparison of the DiFX correlator and the IAA VGOS correlator were obtained. The post-processing software and graphical user interface are close to be completed.