VEGAS Pulsar Project Meeting: 2016 May 2nd 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


  • Randy, Jason, Marty, Justin, John, Natalia, Ryan, Paul


BOF file status updates

Coherent Modes

Mode BOF File Status
c1500x4096 c1500x4096_x14_7_2016_Feb_19_1357.bof GBT Testing; >95% dropped packets in simulator
c1500x2048 c1500x2048_x14_7_2016_Mar_02_1218.bof GBT Testing; >90% dropped packets in simulator
c1500x1024 c1500x1024_x14_7_2016_Mar_16_1434.bof GBT Testing; 22% dropped packets in simulator
c1500x0512 c1500x0512_x14_7_2016_Feb_24_1437.bof GBT Testing; 6% dropped packets in simulator
c1500x0256 c1500x0256_x14_7_2016_Mar_04_1344.bof GBT Testing
c1500x0128 c1500x0128_x14_7_2016_Mar_05_1423.bof GBT Testing
c1500x0064 c1500x0064_x14_7_2016_Mar_09_0820.bof GBT Testing
c0800x4096 c0800x4096_x14_7_2016_Mar_09_1415.bof GBT Testing; occasional < 0.1% packet loss in simulator
c0800x2048 c0800x2048_x14_7_2016_Mar_09_1445.bof GBT Testing
c0800x1024 c0800x1024_x14_7_mt01_2016_Apr_01_1216.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_mt01_2016_Apr_01_1209.bof GBT Testing
  • Outstanding issues
    • Packet loss in high nchan 1500 MHz modes (expected)
    • 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.
    • Randy unsure how to build a 32-channel coherent mode
      • One clock cycle short; In 64 channel-mode 8 clock cycles are needed to read out a spectra. In 32 channel mode, 4 clock cycles are needed, which would require speeding up processing of data through the rest of the design
      • Randy could also add two additional memory banks, each interleaved.
        • There are enough resources on the roach for this, but it would make data handling more complex and likely lead to timing closure issues.
      • Could also drop FPGA DSP and allow everythign to be done on the GPU, but GPU probably can't process that much bandwidth.
      • This mode could be used for very high time resolution, but probably not a common use case.
        • Could develop if time
        • Higher priority than incoherent 32-channel mode.

Incoherent Modes

Mode BOF File Status
i1500x8192 i1500x8192_x14_7_2016_Apr_18_0901.bof GBT Testing
i1500x4096 i1500x4096_x14_7_2016_Apr_18_0932.bof GBT Testing
i1500x2048 i1500x2048_x14_7_2016_Apr_18_1509.bof GBT Testing
i1500x1024 i1500x1024_x14_7_2016_Apr_18_1521.bof GBT Testing
i1500x0512 i1500x0512_x14_7_2016_Apr_18_1253.bof GBT Testing
i1500x0256 i1500x0256_x14_7_2016_Apr_19_0753.bof GBT Testing
i1500x0128 i1500x0128_x14_7_2016_Apr_20_1411.bof GBT Testing
i1500x0064 i1500x0064_x14_7_2016_Apr_19_0813.bof GBT Testing
i0800x8192 i0800x8192_x14_7_2016_Apr_19_0843.bof GBT Testing
i0800x4096 i0800x4096_x14_7_2016_Apr_19_1038.bof GBT Testing
i0800x2048 i0800x2048_x14_7_2016_Apr_19_1048.bof GBT Testing
i0800x1024 i0800x1024_x14_7_2016_Apr_19_1054.bof GBT Testing
i0800x0512 i0800x0512_x14_7_2016_Apr_19_1104.bof GBT Testing
i0800x0256 i0800x0256_x14_7_2016_Apr_19_1242.bof GBT Testing
i0800x0128 i0800x0128_x14_7_2016_Apr_19_1249.bof GBT Testing
i0800x0064 i0800x0064_x14_7_2016_Apr_19_1256.bof GBT Testing
  • Outstanding Issues
    • All existing BOFs look good in simulator
    • Randy building i1500x0032 mode
      • Will require more detailed testing
      • Custom transform for channel ordering
        • Developed software level injection on per-channel basis to use for mapping
        • Seeing duplicale spikes in first 8 channels, still trying to track down

Low bandwidth modes

  • Randy has built 100 MHz and 200 MHz BOFs
    • All channelization will happen in software
    • Need to check software register compatability
      • These are VEGAS designs, so Randy and Jason have not added all the software registers used in pulsar modes (and some do not make sense for the LBW modes)
      • Requires discussion with Justin to make sure software knows how to interface with these designs
        • Action item: Look at current LBW registers and determine which are usually present in pulsar mode that need to be implemented in software

Fast4K and Fast8K Modes

  • GUPPI only uses Fast4K for 100 MHz modes
    • Probably does not require a separate hardware mode
    • Action item: Discuss how to implement in software.


  • 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
        • Only the case for dual backend operation with GUPPI and VEGAS in pulsar modes
  • Matrix HPC
    • No updates
  • Low Bandwidth Modes
  • Manager maintenace
    • Manager core dumps when killed with SIGINT

GBT testing

  • Test spectral line modes, coherent bank behavior, balancing, ADC calibration in coherent modes.

Wideband AP

  • No updates.

VEGAS/DIBAS-style backend for FAST

  • Work progressing as independent project
  • Shop almost finished with it's work. ROACH's may be arriving sooner than expected.

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

  • May 2
-- RyanLynch - 2016-05-02
Topic revision: r2 - 2016-05-02, RyanLynch
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