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Mark IV VLBI Terminal

Consists of a PC running the Field System and controlling the Mark III VLBI Data Acquisition Terminal (DAT). Presently running version 8 of the field system under Venix but will soon be replaced by version 9 which will run under Linux.

During VLBI observing the field system is master of the telescope and bypasses the HP 1000. It sends commands to PC-STEER and has control of all necessary equipment via SDIO (cf. Instrumentation Control section above).

Because the NCCS is supposed to provide an integrated control system with common log files, user interface, file formats etc. VLBI should be better integrated into the control system so that it runs as one of the observing programs in the same way as spectral lines, continuum etc.

The VLBI field system should coexist with the NCCS but be in control during VLBI. Other programs (e.g. Vela monitoring) must not be able to run during VLBI unless called by SNAP commands.

Mike Gaylard