VLBA Terminal at Effelsberg 100m

The 100meter telescope at MPIfR Effelsberg has a VLBA-type data acquisition system to record VLBA formats, and a Mk4 terminal for mk3/4. This describes the use of the VLBA terminal.

Click here for general VLBA information.

Similarities with the VLBA

  • The data acquisition system is very similar to those at all the VLBA stations.
  • There are four double-sideband baseband converters with bandwidths settable between 62.5 KHz and 16 MHz.
  • The recorder can record up to 14 tape passes. Both thin and thick tape can be written. At present this terminal is only used with thin tape at high density.

  • Differences from the VLBA

  • There is only one tape recorder, so users must allow time in the schedule for tape changes (allow 10-15 minutes) and time for postpassing.
  • Quick changes of observing band (40sec) are available in the wavelength range 7mm-13cm. Frequencies outside this range are generally in prime focus and cannot be quickly changed.
  • The 100m is in a valley which restricts elevation coverage.
  • Slew speed is 30/20 degrees per minute in az/el - slower than for VLBA antennas. Source changes of a few arcsec require 7 seconds. For longer moves beware of the acceleration time.
  • Pointing at 1.3cm and 7mm may be a problem. Allow occasional 10 minute gaps for antenna operator to do pointing and focus, particularly after large changes of azel.
  • Continuous calibration is available, phase cal signals are Mk3 1MHz style, currently not available at 18cm.

    Scheduling

    Preparation of standard 'crd' files using sched. These files also control the antenna.

    Observing Bands and LO equations. These are taken care of by the frequency tables in sched.

    Effelsberg Contact people:

  • A. Kraus (email: evlbi@mpifr-bonn.mpg.de; )
  • D. Graham (email: dgraham@web.de; )
  • Telescope operator during observations: +49-2257-301155 )

  • mpifr home page.
  • dave's vlbi home. dave's other vlbi home.

    • last changed this page 2002 February