EVN MkIV DATA PROCESSOR AT JIVE Operational & Development Status Sheet 03 November 2005 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: 13 tape drives are available for thick and thin tape playback; they are equipped with a single (read)head. Spare/replacement parts (heads, capstan motors) are in very short supply. 16 Mk5A systems are available for use (10 attached to SUs in racks: 3 fully attached to SUs). Mixed tape-disk correlation is standard; EVN stations have shifted to all-disk observing. 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: Tape: 4 or 8 Mb/s/track x up to 32 tracks Disk: 4, 8, or 16 Mb/s/track x up to 64 tracks Speed-up (playback speed different from recording speed) is not currently operational, but is being implemented. Data streams: Fan-outs of 1:1, 1:2, or 1:4; using 1 or 2 bit recording; oversampling operational (to x4). Fan-in not planned. Maximum total data rates: Tape: 512 Mb/s - 64 tracks at 8 Mb/s/track; correlated in 2 passes. Disk: 1 Gb/s - 64 tracks at 16 Mb/s/track 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: 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 N_sb*N_pol products correlated per baseline, with a minimum of 16 spectral points per individual product. There is a separate maximum of 16 (subbands)*(parallel polarizations) arising from the station units. Integration Times: Minimum integration time using the whole correlator is 0.25s. For half the correlator, 0.125s is possible. The output rate from the correlator to the data-distribution computer in these maximal cases is 6MB/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 tape-based projects using 64 tracks currently possible by making two passes. 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. 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 (similar information content as VLBA data). 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 Speed-up Development in progress Pulsar gating Designed LIST OF MODES: The following modes were processed successfully: First column indicates the number of projects, followed by the number of bands, filter used, sample rate, number of bits, polarization, sideband, fan-out, and NRAO notation equivalent (tape-speed has been removed as an explicit field). 5 16x16MHz 32Ms/s 2b Dpol Usb 1:2 1024-16-2 1 16x8MHz 16Ms/s 2b Dpol Usb 1:2 512-16-2 11 16x8MHz 16Ms/s 2b Dpol Lsb 1:2 512-16-2 4 16x16MHz 32Ms/s 1b Dpol Lsb 1:4 512-16-1 1 8x16MHz 32Ms/s 2b Dpol Usb 1:4 512-8-2 60 8x8MHz 16Ms/s 2b Dpol Usb 1:2 256-8-2 1 8x8MHz 16Ms/s 2b Dpol Lsb 1:4 256-8-2 8 8x8MHz 16Ms/s 2b Dpol Lsb 1:2 256-8-2 1 8x8MHz 16Ms/s 2b Lpol Usb 1:2 256-8-2 1 8x8MHz 16Ms/s 2b Rpol Dsb 1:2 256-8-2 2 4x16MHz 32Ms/s 2b Dpol Usb 1:4 256-4-2 1 4x16MHz 32Ms/s 2b Dpol Lsb 1:4 256-4-2 1 28x2MHz 4Ms/s 1b Rpol Dsb 1:1 112-28-1 5 8x4MHz 8Ms/s 2b Dpol Usb 1:2 128-8-2 5 8x4MHz 8Ms/s 2b Dpol Usb 1:1 128-8-2 1 8x4MHz 8Ms/s 2b Dpol Lsb 1:2 128-8-2 6 8x8MHz 16Ms/s 1b Dpol Usb 1:4 128-8-1 91 4x8MHz 16Ms/s 2b Dpol Usb 1:4 128-4-2 4 4x8MHz 16Ms/s 2b Dpol Usb 1:2 128-4-2 3 4x8MHz 16Ms/s 2b Lpol Usb 1:4 128-4-2 2 2x16MHz 32Ms/s 2b Dpol Usb 1:4 128-2-2 5 8x2MHz 4Ms/s 2b Dpol Usb 1:1 64-8-2 19 4x4MHz 8Ms/s 2b Dpol Usb 1:2 64-4-2 1 4x4MHz 8Ms/s 2b Dpol Usb 1:1 64-4-2 1 4x8MHz 16Ms/s 1b Dpol Usb 1:1 64-4-1 7 2x8MHz 16Ms/s 2b Dpol Usb 1:4 64-2-2 3 2x8MHz 16Ms/s 2b Dpol Usb 1:2 64-2-2 2 6x2MHz 4Ms/s 2b Dpol Usb 1:1 48-6-2 10 4x2MHz 4Ms/s 2b Dpol Usb 1:1 32-4-2 9 4x500kHz 4Ms/s 2b Dpol Usb 1:1 32-4-2 6 2x4MHz 8Ms/s 2b Dpol Usb 1:2 32-2-2 3 2x2MHz 4Ms/s 2b Dpol Usb 1:1 16-2-2 2 2x2MHz 4Ms/s 2b Dpol Usb 1:1 16-2-2