Daily Image
14-12-2007
eVLBI: First real-time1Gb/s fringes
| Submitter: | Paul Boven |
| Description: | On tuesday we conducted an e-VLBI test during which we observed fringes for the first time from 5 telescopes at network speeds of nearly 1Gb/s per telescope. The VLBI equipment at each of the telescopes is only capable of generating data at certain speeds, e.g. 256Mb/s, 512Mb/s, and the highest datarate is 1024Mb/s. But the 1Gb/s network lightpath connections from the telescopes to JIVE are just a bit too small to handle that highest datarate. With special control software developed at JIVE we can now drop a small amount (~10%) of data before sending it across the network, and at the receiving end substitute error flags for the lost data in order to present the correct datarate to the EVN correlator. This allows us to make the most use of our networking resources, and increase the sensitivity of the e-EVN. The top set of graphs show the actual fringes from each of the participating telescopes against the WSRT (not every telescope had valid data in each subband, so some fringes are missing). The bottom graph shows the network throughput for the various phases of this experiment. |
| Copyright: | JIVE |
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