MPIfR/BKG MKIV CORRELATOR - REPORT TO THE TOG - 30 JUNE 2003 =========================== ================= ============ GENERAL Current correlator capabilities are listed at: http://www.mpifr-bonn.mpg.de/EVN/MK4CORstatus A copy is attached to this report. CORRELATOR HARDWARE > 4 MK5A units were integrated into the correlator. As a default they are connected to the 2nd head input of the station units In this setup all 32 track modes can be correlated either with tape or disk just via a software switch. With simple re-cabling, 1 Gbps correlation can be done in 1 pass. > 101 MK5 8-pack disk containers were bought at the end of 2002. We filled 34 8-packs with 120 GB disks (=272 disks) and 10 8-packs with 200 GB disks (=80 disks). These packs are meant primarily for mm-VLBI. > 240 180 GB disks (=30 8-packs) will be purchased before session 3. > About 50 shipping containers (carboard boxes + foam) will be purchased soon. > Extensive testing of all aspects of MK5 is continuing. The remaining problems are now mostly in the MK5 software. Bitrates up to 1024 Mbps have been tested successfully. > The geodetic community is phasing in MK5 from July, on a station by station basis. > MK4 barrel roll was successfully used in recent 3mm observations by stations On, Eb, Pv. (MK4 barrel role is standard for geodetic observations.) CORRELATION SOFTWARE New correlator software from Haystack includes the following features: > Correlation with MK5A systems works smoothly. Includes log extraction, observe vex, `mounting', positioning to scan, synchronization of data stream. Bank switching is still manual. > A bug in the correlator software was fixed which caused a reduction of the correlation amplitudes for the highest observing frequencies under unfavourable conditions (baseline orientation). 2 complete mm sessions have been re-correlated. > MK4IN has an option to correct the correlator bug for older data sets. OPERATIONS > The first 4-station MK5A-only project was correlated in Bonn. The participating stations were Plateau de Bure, Pico Veleta, HHT and Kit Peak (Arizona). The observing frequency was 230 GHz sampled at a bitrate of 512 Mbps. Fringes were detected between Pico Veleta and Plateau de Bure. For the first time weak transatlantic fringes were found as well. > Tapes from two EVN projects from May/June are being correlated now. R.Porcas W.Alef CAPABILITIES OF THE BONN MK4 VLBI CORRELATOR Version 10: 25 June 2003 INTRODUCTION The Bonn MK4 VLBI correlator is operated jointly by the MPIfR and GIUB (Bonn) and the BKG (Frankfurt). It has 9 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: 9 MK4 tape drives 4 MK5A systems (alternative to a tape drive) Tape types: thick and thin (7 drives optimised for thin) Playback speeds: 80, 160 ips (thin tape); 135, 270 ips (thick tape) speed-up factor of 2 possible for 80 ips recordings (MK5A: up to 1024 Mb/s) SUPPORTED RECORDING Record speeds: 80, 160 ips (thin tape); 135, 270 ips (thick tape) 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 (with 1 head using 2 passes) (and lower bit-rates at 80 ips) MK5A only: 1024-16-2 (all modes in 1 pass) CORRELATION Geometric model: CALC 8 Number of boards: 16 (DSP not yet implemented) Phase cal: single tone extraction at selectable frequency (multi-tone phase-cal not implemented) 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 tested; 4096 maximum Maximum output: 9 stations: 36 baselines, 16 channels, 32 lags with ACF (no cross polarisation) 8 stations: 28 baselines, 16 channels, 32 lags with ACF and full cross polarisation Multiple streams: Maximum of 4 independent correlations for simultaneous correlation of sub-nets, etc. Multiple passes: Supported for >9 stations (up to 13 in 3 passes) 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: DDS2, DDS3 and DDS4 DAT Archive content: root, type1('51'), type2('52'), type3(station-based) Post-cor. software: HOPS data inspection, re-processing software 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 R.Porcas at: http://www.mpifr-bonn.mpg.de/EVN/MK4CORstatus)