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West Coast Spectrometer Team
Mark Wagner, Berkeley project manager, FPGA designer Terry Filiba, data transport: FPGA --> CPU --> GPU Suraj Gowda, boosting FFT/FPGA clock speed Glenn Jones, digital downconverter design (caltech) Guifre Molera, 10Gbit ethernet protocol, GUPPI mods Gregory Desvignes, Guppi Code modificationsSimon Scott, systems integration, arriving march 26 Hong Chen, fft optimizations (bit growth, unscramber) Billy Mallard, DSP library optimizations (DSP48, etc) Andrew Siemion, galactic center pulsar application Dan Werthimer, taking credit for above work
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Roach I vs Roach II
• Roach I works well. Deployed at many observatories• Roach II doesn’t exist. Prototypes spring. Prod Winter?
• Roach I resources are tight, harder to get to work at high speed hard to add features, 500 MHz 8K channels won’t fit
• Roach II can use SFP+ connectors, more reliable 10Gbe connector
• Plan: develop and test using Roach I. Decide later.
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“Automated Placement for Parallelized FPGA FFTs” Suraj Gowda et al, 2011
No Placement Constraint Placement Constrained using our algorithm
Processable Bandwidth <2.4 GHz > 3 GHz
Compile time 80:19 minutes 38:22 minutes
x0 xx1 xx2 xx3 xx4 xx5 xx6 xx7 x
E0(z)
E1(z)
E2(z)
E3(z)
E4(z)
E5(z)
E6(z)
E7(z)
+… y3 y2 y1 y0
8*Fclk real samples per second (BW=4*Fclk)
Fclk cplx samples per second (BW=Fclk)
Existing CASPER DDC/Decimation filterQuarter band filter for 8 real inputs
Multiply by complex sinusoid
Polyphase filter components
Half Band DDC/Filter - Glenn Jones
x0x4 x
x1x5 x
x2x6 x
x3x7 x
E0(z)
E1(z)
E2(z)
E3(z)
… y2 y0
2*Fclk cplx samples per second (BW=2*Fclk)
+
8*Fclk real samples per second (BW=4*Fclk)
v0v4
v1v5
v2v6
v3v7
+
… y3 y1
Preliminary Design Work• Concentrating on the hard parts
– 3 GS/s sampling and PFB/FFT calculations– Heterogeneous Computing Approach
• Divide processing into front/back ends• Use FPGAs to fully process bandwidths greater than 250
MHz• Use FPGA front-ends to pre-process, split and packetize
data, then GPUs to provide fine channelization on narrower chunks
– Software Design• Adapting code from the Green Bank Ultimate Pulsar
Processing Instrument (GUPPI)
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Pulsars at the Galactic Center ??100’s of pulsars predicted in the central pc none undiscovered - Macquart, Frail, Ransom,
Bower..
Map gravitational field (timing), ISM at GC, black hole spin?
Extreme scattering smears out the pulse
High Frequency Observation to minimize scattering
High Bandwidth Needed at High Frequency (low flux) 800 MHz 8 GHz
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