VLBI Data Interchange Format (VDIF) (invited)
Alan R. Whitney, Mark Kettenis, Chris J. Phillips, Mamoru Sekido · 2009
An important outcome of the 7th International e-VLBI Workshop in Shanghai in June 2008 was the creation of a task force to study and recommend a universal VLBI data format that is suitable for both on-the-wire e-VLBI data transfer, as well as direct disk storage.This task force, called the VLBI Data Interchange Format (VDIF) Task Force, is the first part of a two part effort, the second of which will address standardization of e-VLBI data-transmissionprotocols.The formation of the VDIF Task Force was prompted by increased e-VLBI activity and the difficulties encountered when data arrive at a correlator in different formats from various instruments in various parts of the world.The task force has proposed a streaming packetized data format that may be used for real-time and non-real-time e-VLBI, as well as direct disk storage.The data may contain multiple channels of time-sampled data with an arbitrary number of channels, arbitrary #bits/sample up to 32, 'real' or 'complex' data; data rates in excess of 100Gbps are supported.Each data packet is completely self-identifying via a short header, and data may be decoded without reference to any external information.The VDIF draft proposal, with a few minor modifications, was formally accepted at the 8th International e-VLBI Workshop in Madrid in June 2009, and work has already begun by several groups to implement software and hardware support for the VDIF specification.