The Mark 5C VLBI Data System

The Mark 5C disk-based VLBI data system is being developed as the third-generation Mark 5 disk-based system, increasing the sustained data-recording rate capability to 4 Gbps. It is built on the same basic platform as the Mark 5A, Mark 5B and Mark 5B+ systems and will use the same 8-disk modules as earlier Mark 5 systems, although two 8-disk modules will be necessary to support the 4 Gbps rate. Unlike its earlier brethren, which use proprietary data interfaces, the Mark 5C will accept data from a standard 10 Gigabit Ethernet connection and be compatible with the emerging VLBI Data Interchange Format (VDIF) standard. Data sources for the Mark 5C system will be based on new digital backends now being developed, specifically the RDBE in the U.S. and the dBBC in Europe, as well as others. The Mark 5C system is being planned for use with the VLBI2010 system and will also be used by NRAO as part of the VLBA sensitivity upgrade program; it will also be available to the global VLBI community from Conduant. Mark 5C system specification and development is supported by Haystack Observatory, NRAO, and Conduant Corporation. Prototype Mark 5C systems are expected in early 2010.