VEGAS Pulsar Project Meeting: 2016 January 25th 2:00 - 3:00pm ET

Room / Connection Details

• GB-137 / Soc 280
• 192.33.117.12##7144
• 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

Present

• Randy, Jason, Ray, Ryan, Marty, Justin

Agenda

BOF file status updates

• Switching signal builds
  • c1500x4096, i1500x2048, and i0800x2048 all seem to behave in the same manner as the non-SS builds
  • c0800x4096 mode scans fail to initialize. Ryan and Justin currently working on tracking down the cause.
• c1500x4096 mode
  • Recompiled GPU transpose code
    • Complete
  • nVidia profiling
    • BLI found using packet-sockets solves this problem and found them highly efficient. That code is done and available.
      • Will need to integrate this into current code, but other modes have higher priority
      • Ryan to contact Dave McMahon about these changes to see what needs to be done to incorporate them into our "release" (or pre-release versions)
  • guppi_daq_server version comparisons
    • Ryan to test at some point
  • Is this the SS version?
    • Previously no, but Ryan has starting testing this
• c1500x0512 mode
  • Build status
    • Built successfully
  • Scans failing during long integrations
    • Update status shared memory code to use different data type to accurately capture packet ID
      • Need to update guppi_daq status shared memory library. Ray thinks it probably uses a signed variable type instead of an unsigned type.
      • Ryan will try a long scan with a mode that has worked in the past to see what happens to the PKTIDX field
  • Astronomical verification
    • Used successfully during Breakthrough Listen tests (though with some packet loss in the RAW mode)
      • This loss was in the net thread
• c1500x2048 mode
  • Not able to build off of c1500x4096 version
    • Still related to the Xilinx software tools
    • Trying to build a version with SS support. Randy hopes this will change the Xilinx routing enough that it builds successfully
• Fix for nchan calculation in coherent modes
  • verified - ready to roll into other modes
• Bandpass issues in i0800x0064, 0128, 8192
  • Spent some time testing 64 channel mode
  • Injected a digital tone at 100 MHz, which always shows up at the correct frequency
  • Tone shows up in the correct bins, but generates spurs if injected at Fs/8 or nearby
    • Spurs move with the test tone and decrease with amplitude if you move away from Fs/8
    • May be problem with MMCM or OGP calibration
  • A suggestion was made to build a BOF with digital noise source to test
    • tough for 8192, others should be ok
      • test w/ 64 chl mode since testing already done by Jason
    • work needs to prioritized against other work
  • Jason worked with VEGAS hardware and saw same issues as on srbs
    • On srbs, spurrs were showing up when injecting a tone at Fs/4
    • On VEGAS with AP, spectrum still looked poor, with spurs showing up
    • Email Paul to discuss OGP and MMCM calibration, which is currently not being done
    • MMCM is recalibrated each time a new BOF is loaded. OGP solutions are read out of a file.
    • Do we need config files for individual pulsar modes, or is it enough to have configs for the appropriate clock rates?
  • DIBAS have clean bandpasses in those modes
• Duplicated signal in i0800x8192
• Low bandwidth modes
  
  • New filter coefficients
  • Spectrum output instead of time series
  • Implement PFB code
  • Could single GPU keep up with coherent dedispersion?
  • Reviewed John's email suggestion with Paul - more detailed query with John recommended
    • Is there an advantage to FFTs in FPGA? (none identified)
    • GPU (S/W) vs. FPGA (H/W)
      • GPU likely preferable if it can handle it
        • requires a benchmarking test
        • existing FPGA filter work could be affected
      • S/W CUDA-savvy resource constrained
        • Justin will look at it
    • How about running a higher bandwidth modes and ignoring some of the spectra?
      • limits on number of channels likely an issue
    • Ryan to email John to discuss some of this

Software

• Configtool changes
  • Status of rebasing on current release version
    • After next M&C Release
    • Dual backend code added but not system tested
      • Justin and Ryan to test this week during maintenance
• GBT Status shared memory parameters in PSRFITS headers
  • Done
• Switching signal generation
  • Cal successfully controlled by VEGAS
  • Actual swper still not matching requested swper
    • Ryan, Justin, and Ray to talk this week about how the calculation of swper needs to be modified
• Matrix HPC
  • Justin has all threads running for all observing modes, and FITS files are being written
    • Need to check that FITS files are being written properly; Ryan to help with this
    • Richard suggests automating this by comparing FITS files with standards that are known to be correct
  • Justin working on VEGAS Manager to use Matrix instead of older guppi_daq
    • Justin hopes to have this done within 1--2 weeks.

GBT testing

• Testing VPM/GUPPI dual backend config tool this week

Wideband AP

• Status of new filters
  • Should be here in about 1 week

VEGAS/DIBAS-style backend for FAST

• Work progressing as independent project
• Preparing full proposal
  • Target of Feb 5 for internal submission
  • Working on compling documentaiton needs

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

• February 1