CAPABILITIES OF THE BONN MK4 VLBI CORRELATOR

                  Version 12:   15 January 2009                    

INTRODUCTION
          The Bonn MK4 VLBI correlator is operated jointly by the MPIfR
and GIUB (Bonn) and the BKG (Frankfurt). It has 12 disk playback units and can
correlate up to 16 channels of MK3, MK4 or VLBA formatted data from each
in a single correlation pass. The current capabilities are summarised below. 
For further information contact the Correlator Manager, Walter Alef:
       =====> walef@mpifr-bonn.mpg.de

PLAYBACK UNITS
  Number available:   8 Mark 5A systems 
                      4 Mark 5B systems
  Playback speeds:    real-time up to 1024 Mb/s 
                      (2024 Mb/s slowed down by a factor of 2)

SUPPORTED RECORDING
  Record data-rates:  any supported by Mark 5    
  Formats:            MK3/MK4/VLBA (MK4/VLBA w/wo barrel roll, data demod.)
  Sampling:           1 or 2-bit  (over-sampling not yet tested)
  Fan-out:            1:1  1:2  1:4  (fan-in not supported)
  No. of channels:    <= 16, USB and/or LSB 
                      (multiple passes supported for >16 channels in MK4IN)
  Bandwidth/channel:  ....2, 4, 8, 16 MHz
  Signals:            mono, dual frequency or dual polarisation
  Modes:              MK3:  B, C, BB, CC; A, AA (in 2 passes)

                      128-16-1  128-16-2  128-8-1
                      128-8-2   128-4-1   128-4-2
                      128-2-2   256-16-1  256-16-2
                      256-8-1   256-8-2   256-4-2
                      512-16-2  512-8-2  1024-16-2 
                      2048 Mb/s with Mark 5B+

CORRELATION
  Geometric model:    CALC 8
  Number of boards:   16 (DSP not yet implemented)
  Phase cal:          dual tone extraction at selectable frequencies
                          (single-tone analysed)
  Pre-average times:  0.2 -> 5 s  (default 2 s; 60/N s, N an integer; short
                          integration times not with full correlator capacity)
  Lags per channel:   32 minimum  (==> frequency resolution = BW/16)
                          1024 maximum
  Maximum output:     8 stations: 28 baselines, 16 channels, 32 lags
                          with ACF and full cross polarisation
                          (higher output possible, but untested)
                      10 stations tested with single polarisation and ACF
                          (requires mixture of Mark 5A and 5B)
  Multiple streams:   Maximum of 4 independent correlations for
                          simultaneous correlation of sub-nets, etc.
  Multiple passes:    Supported for >8 stations (up to 16 in 6 passes or less)
  Fringe-fit:         Off-line FOURFIT run. (Dual frequency in single
                          execution: dual/cross-polsn. in multiple executions)

AUXILIARY FILES
  Correlator control: Observing VEX file (from SKED or SCHED)
  Station logs:       Standard FS logs, VLBA logs
  GPS data:           EVN and VLBA standard formats

ARCHIVE AND EXPORT
  Archive medium:     DDS4 DAT, hard disk
  Archive content:    root, type1('51'), type2('52'), type3(station-based)
                          and FITS for astronomical observations
                          Data-base for geodetic observations
  Post-cor. software: HOPS data inspection, re-processing software
                      data-base generation and interface to CALC/SOLV 
                      interface to AIPS using task MK4IN via HOPS with
                      automatic application of phase-cal and other corrections,
                      transfer of FOURFIT solutions (AIPS task BLAPP).


(Maintained by W.Alef at:   http://www.mpifr-bonn.mpg.de/EVN/MK4CORstatus)