EVN MkIV DATA PROCESSOR AT JIVE Operational & Development Status Sheet 13 November 2006 OPERATIONAL HOURS: Operational hours: 80/week. We are currently using a three-week cycle of 80-80-40 hr/week. Typically 60-70% of the time is spent on user experiments, the remainder being tests of new features/bug fixes, NME/network-test processing, and equipment upgrades/casualties. CURRENTLY OPERATIONAL SYSTEM: 16 Mk5A systems are available for use (all now housed in racks, both head-stacks connected to SUs). 9 tape drives are available for thick and thin tape playback; they are equipped with a single (read)head. Can be connected to an SU through reconnecting a pair of cables. Most experiments are now disk-only, but correlation of mixed tape-disk observations is also standard. MkIV, VLBA, Mk5, MkIII playback without barrel-roll (for tapes), including modulation for VLBA format. Multiple projects per disk-pack is supported. Supported recording speeds: Disk: 4, 8, or 16 Mb/s/track x up to 64 tracks Tape: 4 or 8 Mb/s/track x up to 32 tracks Data streams: Fan-outs of 1:1, 1:2, or 1:4; using 1 or 2 bit recording; oversampling operational (up to 4 times Nyquist). Fan-in not planned. Maximum total data rates: Disk: 1 Gb/s - 64 tracks at 16 Mb/s/track Tape: 512 Mb/s - 64 tracks at 8 Mb/s/track; correlated in 2 passes. Bandwidths: 500kHz, 1 MHz (both via oversampling), 2, 4, 8, 16 MHz. Sidebands: Upper, Lower, or Dual Polarization: Single or Dual or Cross (mixed single- and dual-pol channels in an experiment need to be correlated in separate passes) Sampling: 1 or 2 bits per sample (correlation of experiments in which some stations record at 2-bit sampling and some at 1-bit sampling is also possible). CORRELATION: Spectral Capacity (full correlator in local validity): 9-16 telescopes: 512 spectral points/baseline 2-8 telescopes: 2048 " " These spectral points must be spread evenly over the product of the number of subbands times the number of polarizations correlated per baseline, with a minimum of 16 spectral points per individual Bsln/SB/Pol. There is a separate maximum of 16 (subbands)*(parallel polarizations) arising from the station units -- i.e., either 16 single-pol subbands or 8 dual-pol subbands (regardless of whether cross-pols are correlated). Integration Times: Minimum integration time using the whole correlator is 0.25s. The maximum output rate from the correlator to the data-distribution computer is 6 MB/s (data in lag-space; includes ancillary header information). Exceeding Correlator Capacity via Multiple Passes: Correlation of projects with more than 16 stations recording simultaneously is possible by processing in multiple passes and automatically merging the data. For 17-24 stations, 3 passes would be required to ensure coverage of all baselines. Correlation of multiple-subband experiments at a higher spectral resolution than permitted by the full set of N_sb*N_pol can be done in multiple line/continuum passes, in which a smaller set of N_sb or N_pol may be correlated separately, each with higher number of spectral points. The "Spectral Capacity" numbers above represent the current maximum per SB/pol if done in separate passes. Correlation at multiple phase-centers currently supported by multiple passes. Correlation of tape-based projects using 64 tracks currently possible by making a separate pass per head-stack. No automated handling of sub-netted observing schemes yet (but can be manually made to work in reasonable cases). No space VLBI support. OUTPUT DATA FORMAT: Data is transfered to aips++ measurement sets (MS version 2), reviewed, and exported to IDI Fits, ready for processing in classic AIPS. The data-size the user would receive at the full output rate is on the order of 7-12 GB/hr (FITS files with higher numbers of frequency points seem to be larger for a given raw-correlator ouput size). The correlator archive consists of raw data files in JIVE specific format. The EVN Archive provides access to the standard-plots, pipeline results, station feedback, and FITS data. The EVN Archive release policy came into effect on 1 June 2004. In aips++ standard flagging is done (rate zero crossings, playback quality threshold). A better amplitude compensation for the 2-bit van Vleck correction is performed post-correlation for each visibility. ENHANCEMENT PROJECTS: Description Status -------------------------------------------------------------------------- Calibration transfer Being verified PCInt: data rate >6MB/s Development in progress Phase-cal detection Development in progress Recirculation Development in progress Pulsar gating Designed LIST OF MODES: The following modes were processed successfully. The columns indicate the number of BBs (N_sb * N_parellel.pol) times the filter used, the sample rate, the number of bits per sample, the polarization, the fan-out, and the corresponding NRAO notation equivalent. 16x16MHz 32Ms/s 2b Dpol 1:2 1024-16-2 16x8MHz 16Ms/s 2b Dpol 1:2 512-16-2 16x16MHz 32Ms/s 1b Dpol 1:4 512-16-1 8x16MHz 32Ms/s 2b Dpol 1:4 512-8-2 16x4MHz 8Ms/s 2b Dpol 1:1 256-16-2 8x8MHz 16Ms/s 2b Dpol 1:4 256-8-2 8x8MHz 16Ms/s 2b Dpol 1:2 256-8-2 8x8MHz 16Ms/s 2b Lpol 1:2 256-8-2 8x8MHz 16Ms/s 2b Rpol 1:2 256-8-2 4x16MHz 32Ms/s 2b Dpol 1:4 256-4-2 16x2MHz 4Ms/s 2b Dpol 1:1 128-16-2 28x2MHz 4Ms/s 1b Rpol 1:1 112-28-1 8x4MHz 8Ms/s 2b Dpol 1:2 128-8-2 8x4MHz 8Ms/s 2b Dpol 1:1 128-8-2 8x4MHz 8Ms/s 2b Lpol 1:1 128-8-2 8x8MHz 16Ms/s 1b Dpol 1:4 128-8-1 4x8MHz 16Ms/s 2b Dpol 1:4 128-4-2 4x8MHz 16Ms/s 2b Dpol 1:2 128-4-2 4x8MHz 16Ms/s 2b Lpol 1:4 128-4-2 2x16MHz 32Ms/s 2b Dpol 1:4 128-2-2 8x2MHz 4Ms/s 2b Dpol 1:1 64-8-2 4x4MHz 8Ms/s 2b Dpol 1:2 64-4-2 4x4MHz 8Ms/s 2b Dpol 1:1 64-4-2 4x8MHz 16Ms/s 1b Dpol 1:1 64-4-1 2x8MHz 16Ms/s 2b Dpol 1:4 64-2-2 2x8MHz 16Ms/s 2b Dpol 1:2 64-2-2 6x2MHz 4Ms/s 2b Dpol 1:1 48-6-2 4x2MHz 4Ms/s 2b Dpol 1:1 32-4-2 4x500kHz 4Ms/s 2b Dpol 1:1 32-4-2 2x4MHz 8Ms/s 2b Dpol 1:2 32-2-2 2x2MHz 4Ms/s 2b Dpol 1:2 16-2-2 2x2MHz 4Ms/s 2b Dpol 1:1 16-2-2