VEGAS Pulsar Project Meeting: 2016 April 4th 2:00 - 3:00pm ET

Room / Connection Details

  • GB-137 / Soc 280
  • 434-817-6443

Housekeeping Details

  • Main wiki page
  • gbsapp Mailing List
  • Location and regular date and time of meeting - agreed weekly on Mondays; GB-137 / Soc-280; 2-3pm ET
  • ETK codes:
    • Electronics: 432510.GB3015
    • Software: 893252.GB3015
    • Science: 432540.GB3015

Resource Allocations

LYNCH, Ryan 0.25


  • Vereese, Richard, Marty, Ryan, John


BOF file status updates

Coherent Modes

Mode BOF File Status
c1500x4096 c1500x4096_x14_7_ss_2015_Dec_16_1447.bof GBT Testing; dropping packets
c1500x2048 c1500x2048_x14_7_2016_Mar_02_1218.bof GBT Testing; dropping packets
c1500x1024 c1500x1024_x14_7_2015_Jul_25_1525.bof Needs SS Build
c1500x0512 c1500x0512_x14_7_2016_Feb_24_1437.bof GBT Testing
c1500x0256 c1500x0256_x14_7_2016_Mar_04_1344.bof GBT Testing
c1500x0128 c1500x0128_x14_7_2016_Mar_05_1423.bof GBT Testing; some dropped packets
c1500x0064 c1500x0064_x14_7_2016_Mar_09_0820.bof GBT Testing
c0800x4096 c0800x4096_x14_7_2016_Mar_09_1415.bof GBT Testing
c0800x2048 c0800x2048_x14_7_2016_Mar_09_1445.bof GBT Testing
c0800x1024 c0800x1024_x14_7_2016_Mar_09_1450.bof GBT Testing; MMCM calibration problems
c0800x0512 c0800x0512_x14_7_2016_Mar_14_1421.bof GBT Testing
c0800x0256 c0800x0256_x14_7_2016_Mar_10_1136.bof GBT Testing; MMCM calibration problems
c0800x0128 c0800x0128_x14_7_2016_Mar_10_1144.bof GBT Testing
c0800x0064 c0800x0064_x14_7_2016_Mar_11_0859.bof GBT Testing
  • Outstanding issues
    • Packet loss in c1500x4096 and c1500x2048 modes not unexpected. Action item: Talk to Dave McMahon in April about optimization for BL that we can pull in for VPM.
    • Packet loss in c1500x0128 mode is somewhat surprising, given that higher-channel modes seem to work well.
      • Ryan to talk with Joe/Randy about possible reasons for this on the guppi_daq side.
    • MMCM calibration failing for zdok1 for c0800x1024 and c0800x0256
      • Ryan, Justin, and Paul M. looked at low-level MMCM calibration independent of any other software. Calibration looks OK for the first ADC card, but the second has glitches across all channels looked at by Paul's script (I think there were 16). While this is mostly reproducible, it did appear that one or two configurations and calibrations did succeed.
      • We attempted to check other ROACHes but were not able to immediately configure for this mode.
      • Probably related, the adcpower2 samplers report constant values of 128 across all channels (determined with Device Explorer)
      • Also probably related, the VEGAS power samplers report a power of -inf for the J2 input.

Incoherent Modes

Mode BOF File Status
i1500x8192 i1500x8192_x14_7_2015_Jul_21_1543.bof Sim Testing; Insufficient memory in folding block
i1500x4096 i1500x4096_x14_7_2015_Jun_26_0835.bof Needs SS Build
i1500x2048 i1500x2048_x14_7_ss_2015_Dec_15_1510.bof GBT Testing
i1500x1024 i1500x1024_x14_7_2015_Jun_26_1625.bof Needs SS Build
i1500x0512 i1500x0512_x14_7_2015_Jul_01_1649.bof Needs SS Build
i1500x0256 i1500x0256_x14_7_2015_Jul_17_0922.bof Needs SS Build
i1500x0128 i1500x0128_x14_7_2015_Jul_17_1605.bof Needs SS Build
i1500x0064 i1500x0064_x14_7_2015_Jun_01_1918.bof Needs SS Build
i0800x8192 i0800x8192_x14_7_2015_May_30_1752.bof Duplicate Pulse Signal; Needs SS Build
i0800x4096 i0800x4096_x14_7_2015_May_22_2349.bof Needs SS Build
i0800x2048 i0800x2048_x14_7_ss_2015_Dec_16_1028.bof GBT Testing
i0800x1024 i0800x1024_x14_7_2015_May_13_2000.bof Needs SS Build
i0800x0512 i0800x0512_x14_7_2015_May_17_2357.bof Needs SS Build
i0800x0256 i0800x0256_x14_7_2015_Jun_04_2301.bof Needs SS Build
i0800x0128 Incorrect Bandpass; Needs SS Build
i0800x0064 i0800x0064_x14_7_2015_May_30_1719.bof Incorrect Bandpass; Needs SS Build
  • Outstanding Issues
    • i0800x0064 and i0800x0128 modes have incorrect bandpass shapes
      • Seem to have excess power in higher channels relative to lower channels
      • Injected tone is showing up at correct frequency
      • Spurs are seen at Fs/4 on both SRBS and VEGAS
      • OGM/MMCM calibration should be OK
    • i0800x2048 shows a duplicate pulsed signal, almost as if folding period is twice what it should be
    • i1500x8192 has problem in guppi_fold_thread
      • Error (guppi_fold_thread): Insufficient memory per block to hold fold results.
      • How much memory is available?
  • Randy working on adding SS support and correct bandpass saturation behavior, will continue builds off parent version

Low bandwidth modes

  • Current plan is to perform filterbank FFTs on GPU
    • Makes BOF file builds simpler
    • Requires CUDA development
    • Time series would be fed to HPC, which would perform PFB - corner turn - FFT - complex multiply - FFT - accumulate
      • Everything after corner turn exists in the coherent dedispersion algorithm
      • GPU code exists for PFB and corner turn in spectral line modes but needs to be merged with pulsar code


  • Coherent mode scans are failing to initialize in the simulator
    • Justin and Ray seemed isolated the problem to scans that are started by the Manager
      • They are able to manually configure and start scans (through Grail?) without issue
      • Possible timing problem?
      • Action item: Jason to double check that the SSDS on srbs isn't causing a problem.
        • Complete. SSDS appears to be set up properly.
      • Action item: Ryan to look at phase diagrams to see if SS is being set properly in simulator.
      • Action item: Jason also to look at dummy I2C module on srbs to make sure there isn't a problem there.
      • Action item: John suggests making sure that the Valon synth frequency is being set in the right order
      • Action item: Vereese suggests checking that there are appropriate sleep statements in the manager.
  • Configtool changes
    • Astrid still reports that VEGAS failed to balance when trying to adjust LBW gain. Still need to work on disabling this for pulsar modes.
    • Astrid still issues a warning about a discrepancy in the requested and actual IF rack power levels, though this did not cause a failure
      • This is because GUPPI and VEGAS have different power requirements. Dave Frayer suggested that VEGAS in wide bandwidth modes did not need to have it's targets set so high (currently 3 V). Could we use the same target (1 V) for GUPPI and VEGAS?
      • Justin has fixed this by setting target levels to 1 V for both GUPPI and VEGAS
        • Does this only apply in pulsar mode? Or in dual backend mode?
  • Spectral line modes
    • We are getting what appear to be digital artifacts across the band when trying to configure for a spectral line mode using the pulsar software.
    • Example below is for VEGAS Mode 3. There appear to be 32 spikes across the band.
      VEGAS MODE3 VPMsoft.png
  • Matrix HPC
    • No updates
  • Low Bandwidth Modes
    • No updates

GBT testing

  • Will attempt to test some incoherent mode BOF files and more spectral line modes. Maintenance time is limited and software group is limited this week.

Wideband AP

  • Vereese going to WVU with Richard and Jason on April 25th to receruit a student to work on dispersive transmission line
  • Vereese and Randy to work on hardware aspects in April

VEGAS/DIBAS-style backend for FAST

  • Work progressing as independent project
  • Contract negotiations ongoing. Waiting on response from FAST.

Multicasting for spectral line and pulsar modes

  • Modifications to ROACH configuration and net task must bind to a multicast group instead of a specific host
    • All the 10-gig addresses on the ROACH would be multicast groups, and config will be told which to bind to
    • Some changes to net task code (in VEGAS HPC and guppi_daq code) to initialize sockets

Date / Time of Next Meeting

  • April 11

-- RyanLynch - 2016-04-04
Topic attachments
I Attachment Action Size Date Who Comment
VEGAS_MODE3_VPMsoft.pngpng VEGAS_MODE3_VPMsoft.png manage 5 K 2016-04-04 - 11:53 RyanLynch VEGAS Mode 3 with VPM software
VEGAS_MODE3_VPMsoft.psps manage 166 K 2016-04-04 - 11:54 RyanLynch VEGAS Mode 3 with VPM software
Topic revision: r2 - 2016-04-04, RyanLynch
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