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
BLOSS, MARTIN ALAN
0.05
CREAGER, RAY
0.50
DEMOREST, PAUL
0.05
RICHMOND-DECKER, JUSTIN
0.70
FORD, JOHN M
0.05
MCCULLOUGH, RANDY L
0.50
RAY, JASON
0.10
PRESTAGE, RICHARD
0.05
LYNCH, Ryan
0.15
VAN TONDER, VEREESE
0.20
Present
Vereese, Jason, Randy, Ray, John, Justin, Ryan, Richard, Paul
Agenda
BOF file status updates
Switching signal builds
Randy starting buidling fully cleaned up BOF files
Ready to try "final" version of c1500x4096
c1500x1024 currently building
Ryan to let Jason and Randy know about mode priorities for dual back-end use
c1500x4096, i1500x2048, and i0800x2048 all seem to behave in the same manner as the non-SS builds
c0800x4096 mode scans fail to initialize
NETSTAT appears to remain in "Waiting" for too long, and Manager aborts because the hpc process is taking too long to start
This is because packets are not flowing
Ryan to double check addresses
Can also try it in DIBAS
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
No update
Is this the SS version?
This has been tested and performs identically to the previous build, i.e. scans run but with dropped packets.
c1500x0512 mode
Astronomical verification
Used successfully during Breakthrough Listen tests (though with some packet loss in the RAW mode)
Ryan talked with Andrew Siemion about analysis of their pulsar data. This will be done in the near future.
c1500x2048 mode
Randy built a version with SS support
Ryan tested but there problems with bandpass
Low channels appeared to completely saturate, despite raw counts being within an acceptable dynamic range
Higher channels seemed OK
Randy and Jason are looking into the problem with this build
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
DIBAS modes have clean bandpass
On VEGAS with AP, spectrum still looked poor, with spurs showing up
Result of discussions with Paul regarding OGP/MMCM calibration
We think this already should be happening correctly
Duplicated signal in i0800x8192
Low bandwidth modes
Need to decide on how to proceed with FFTs being done either on FPGA or by GPU. This is a hardware vs software approach.
If bandwidth is low enough all processing could be done on the GPU instead of the FPGA, but is there any advantage one way or the other?
More precision in the GPU
Could use one HPC to process full 200 MHz, otherwise need to do FFT on the FPGA
GPU code would have to do filterbank, not just coherent dedispersion
If done on the GPU, very minor changes to the BOF files, but need CUDA development (personnel is a problem)
If it is done on the FPGA, new BOFs have to be built, not clear how this would be done
In coherent dedispersion, time series would be fed into HPC, which would do a PFB/FFT, corner turn, FFT, complex multiply, FFT, accumulate
Need to add the PFB/FFT and corner turn, the rest is part of the coherent dedispersion algorithm
In incoherent mode, just do the PFB/FFT and then accumulate
Roach output would be the same as the spectral line modes, so we would have to merge the PFB/FFT, corner turn, and coherent dedispersion blocks, but these all exist
Another option is to use DSPSR, which can already do everything, but would use shared memory, which is going away
Software
Configtool changes
Justin merged several changes to the release branch into the VPM branch, and this seems to have fixed the bandpass problems in the IF module
Most likely related to outdated I2C control for the old IF modules
Astrid still reports that VEGAS failed to balance when trying to adjust LBW gain. Still need to work on disabling this for pulsar modes. However, we can now set independent scale parameters for GUPPI and VEGAS.
Astrid still issues a warning about a discrepancy in the requested and actual IF rack power levels, though this did not cause a failure
An observer already expressed interest in configuring GUPPI and VPM in slightly different modes. We parameters allow for this now that we can control the scale parameter separately?
Bandpass is flipped. This is expected because VEGAS has a different sense than GUPPI
OBSBW parameter in shared memory
Manager takes care of shared memory, so this will need to be updated
Currently hardcoded into GUPPI manager. Will need to update this for VEGAS, but this functionality is not in the spectral line manager because it is taken care at the filling stage
It seems like it would be best for config tool to communicate to VEGAS so that shared memory can be set correctly
GUPPI gets the sky center frequency from the status database, but not sure how it sets the sign of OBSBW
Look into getting the necessary information from the status daemon
Also look at DIBAS, since that should probably be doing this correctly already
Switching signal generation
Cal successfully controlled by VEGAS
Actual swper still not matching requested swper
Still outstanding
Justin to work on it some more this week
Incidentally, in dual backend mode DCR was automatically chosen as switching signal master
Matrix HPC
Ray has been working on and seems to be happy with his work on the LBW modes
GBT testing
Verification of spectral line modes with VPM software
Richard to send Ryan some scripts that were used for spectal line mode testing
Wideband AP
Still waiting on new circuit boards
VEGAS/DIBAS-style backend for FAST
Work progressing as independent project
Any overlapping work to note at this time?
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