Swinburne Baseband Recorders etc 1998: Canadian S2 to computer (16 MHz x 2) 100K system + video tapes 2000: CPSR 20 MHz x 2 + DLT7000 drives x 4 2002: CPSR2 128 MHz x 2 + real-time supercomputer (60 cores) 2006: DiFX (Deller, Tingay, Bailes & West) Software Correlator (ATNF adopted) 2007: APSR 1024 MHz x 2 + real-time supercomputer (160 cores) 2008: MultiBOB 13 x 1024 ch x 64us + fibre + 1600-core supercomputer
dspsr software Mature Delivers < 100 ns timing on selected pulsars Total power estimation every 8us with RFI excision Write a “loader” Can do: Giant pulse work Pulsar searching (coherent filterbanks) Pulsar timing/polarimetry Interferometry with pulsar gating
PSRDADA (van Straten) psrdada.sourceforge.net Generic UDP data capture system (APSR/MultiBOB) Ring Buffer(s) Can attach threads to fold/dedisperse etc Hierachical buffers Shares available CPU resources/disk Web-based control/monitoring Free! + hooks to dspsr & psrchive.
APSR Takes 8 Gb/s voltages Forms: 16 x 128 channels (with coherent dedispersion) 4 Stokes, umpteen pulsars Real-time fold to DM=250 pc/cc. O(100) Ops/sample Sustaining >>100 Gflops ~100K computers. June 2008 192 MHz working @ 4bits 768 MHz working @ 2bits
Coherent Dedispersion BW/time 1998 2000 2002 2004 2006 2008 x x x x 16 20 128 1024 (100K) (300K) BW year
Coherent Dedispersion Now “trivial” FFT ease ~ B -2 / 3
MultiBOB High Resolution Universe Survey (PALFA of the South) Werthimer’s iBOB boards 1024 channels, down to 10us sampling Two pols FPGA coding hard… Use software gain equalizer/summer ~5 MB/s beam 1 Gb/s Fibre to Swinburne (>1000 km fibre) Real time searching!
MWA Samples Takes (24x1.3MHz=32 MHz) x 2 x 512 “Just” 32 GB/s (64 Gsamples/s) FFTs it (5 N log2 ops/pt = 2.2 Tflops) XMultiplies & adds (512)*256*B*4 = 16 TMACs
Sensitivity: ~3-5x PKS 32 vs 288 MHz 350 vs 25 K 700 vs 0.6 deg 2 (folded factor)
PKS vs MWA G ~ 3-5 x better T sys ~ 14 x worse ? B 1/2 ~ 3 x worse Flux ~ 25 x better (1400 vs 200 MHz) t 1/2 ~ 32 x better ~ Parity Single Pulse work ~ Comparable Coherent search ~ 32x improvement! But: There is a limit to the time you can observe a pulsar! 4m vs 144m -> 5x deeper.
Build Your Own Telescope? May be cheaper to build dedicated PSR telescope than attempt to process everything from existing telescopes! 32x32 tile: (2D FFT - 1D FFT - dedisperse - FFT) ~2M telescopes ~2M “beamformer/receivers” ~1M correlator ~1M Supercomputer ~1M construction ~7-8M
Next-Gen Supercomputers (IO or Tflops?) Infiniband 20 Gb (40Gb) 288 port switch ~10 Tb/s IO Capacity (1-2K/node) Teraflop CPU capacities/node (140 Gflops now) Teraflop Server or Tflop GPU? 10 GB/s vs 76 GB/s Power (0.1W/$) 2M = 200 kW
Summary: Strong motivation for multiple (~100) tied array beams PSRs/deg^2 Surveys only possible with compact configurations At present Future Supercomputers may allow search even with MWA-like telescopes
Your consent to our cookies if you continue to use this website.