EVN MkIV DATA PROCESSOR AT JIVE Operational & Development Status Sheet 14 September 2008 OPERATIONAL HOURS: Operational hours: 80/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 Mark 5A+ systems are available for use (all now housed in racks, both head-stacks connected to SUs). The Mark 5A+ units can play back either Mark 5A or Mark 5B recordings. Playback of: MkIV, VLBA (including data modulation), Mark5A, Mark5B (via Mark5A+) Supported recording speeds: Disk: 4, 8, or 16 Mbps/track x up to 64 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 (single pass): Disk: 1 Gbps - 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 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. For correlation modes that use half or less of the correlator, 0.125s integration times seem possible. 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 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. Cross-pol correlations can not be split by polarization. Correlation at multiple phase-centers currently supported by multiple passes. Correlation of projects with more than 16 stations recording simultaneously is possible by processing in multiple passes and merging the data to remove redundant visibilities. For 17-24 stations, 3 passes would be required to ensure correlation of all baselines. No automated handling of sub-netted observing schemes (but can be manually made to work in reasonable cases). OUTPUT DATA FORMAT: Data is transformed into aips++ measurement sets (MS version 2), reviewed, and then transformed to IDI Fits, ready for processing in classic AIPS. The data-size the user would receive at the maximum correlator-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. ENHANCEMENT PROJECTS: Description Status -------------------------------------------------------------------------- Phase-cal detection Being verified Recirculation Development in progress Native Mark 5B playback Development in progress LIST OF MODES: The following modes have been processed successfully. The columns indicate the number of BBs (N_sb * N_parallel.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 16x8MHz 16Ms/s 2b Lpol 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