VEGAS Pulsar Project Meeting: 2016 April 18th 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



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
      • Low-level checks of MMCM calibration show glitches across all channels on the second ADC card.
      • Randy Suggested that placement of some blocks in these BOFs was not optimal. Two new builds to test this week.

Incoherent Modes

Mode BOF File Status
i1500x8192 i1500x8192_x14_7_2016_Mar_24_1144.bof GBT Testing
i1500x4096 i1500x4096_x14_7_2016_Mar_28_1209.bof GBT Testing
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_2016_Apr_07_0818.bof Incorrect packet rate
i1500x0064 i1500x0064_x14_7_2016_Apr_12_0747.bof Incorrect packet rate
i0800x8192 i0800x8192_x14_7_2016_Apr_12_0930.bof Incorrect packet rate
i0800x4096 i0800x4096_x14_7_2016_Apr_12_0944.bof Incorrect packet rate
i0800x2048 i0800x2048_x14_7_2016_Apr_12_0951.bof GBT Testing
i0800x1024 i0800x1024_x14_7_2016_Apr_12_0959.bof Incorrect packet rate
i0800x0512 i0800x0512_x14_7_2016_Apr_12_1126.bof Incorrect packet rate
i0800x0256 i0800x0256_x14_7_2016_Apr_12_1133.bof Incorrect packet rate
i0800x0128 i0800x0128_x14_7_2016_Apr_12_1138.bof Incorrect packet rate
i0800x0064 i0800x0064_x14_7_2016_Apr_12_1143.bof Incorrect packet rate
  • Outstanding Issues
    • Packet rate
      • Packets are being sent at 25% the expected rate for most new incoherent designs. Cause still unknown.

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.
        • Complete. No apparent issues.
      • 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.
        • Justin added additional sleep statements but this seemed to have no effect.
  • 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
    • Justin identified some difference in the order of operations between VPM and release branch. This was probably causing some of the shared memory parameters to be computed incorrectly. Both versions now match and shared memory looks identical between the two branches.
      • Ryan and Justin will test using VEGAS this week.
      • Can unused shared memory parameters be cleared after a mode change?
  • Matrix HPC
    • No updates
  • Low Bandwidth Modes
    • No updates

GBT testing

  • Test spectral line modes, balancing, and coherent modes.

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 25

-- RyanLynch - 2016-04-04
Topic revision: r2 - 2016-04-18, RyanLynch
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