April 8/9, 2003 Green BankGBT PTCS Conceptual Design Review

John Ford

August 5, 2008

CICADA Project

The NRAO is operated for the National Science Foundation (NSF)

by Associated Universities, Inc. (AUI), under a cooperative

agreement.

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Outline

• CICADA– Program organization– Assets– GUPPI

• Future directions

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CICADA

• Configurable Instrument Collection for Agile Data Acquisition– FPGA based data acquisition and

processing– Uses CASPER tools and hardware

• Umbrella program for organizing FPGA projects– Purchase/obtain boards, software, development systems– 2 BEE2, 5 iBOB, 6 ADC, 10 GbE switches, servers, etc.

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CICADA Projects

• Spectrometers– KFPA backend– Replacement for GBT Spectrometer

• Event capture• Pulsar machines

– Incoherent machines• Spigot replacement

– Coherent dedispersion machines

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Basic KFPA Spectrometer 2 GHz bandwidth, 32K channels

• CASPER Hardware– 14 ROACH/ROACH-II boards, ADC's – Needs to be in receiver room, fiber to lab

• EVLA Station boards plus CASPER software– Uses standard EVLA hardware– Directly compatible with EVLA digitizers– External supplier

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GUPPI History

• GBT Future Instrumentation Workshop, September 2006

• University of Cincinnati Group worked on it until May, 2007, Produced report and basic design

• 2 WVU summer students and Glen Langston built “event capture” device over the summer

• Scott Ransom yells at us to “stop planning and get to work” in August, 2007

• October 29th, 2007, Held workshop to brainstorm the project and get started on detailed design and implementation

• April 4th, first pulsar observation (under test conditions with 43m telescope)

Another pulsar backend? We already have 5!

GUPPI: 8-bit, 800MHz, 4096 chan, Full Stokes, and coherent dedisp

BCPM: 4-bit, 48-96MHz, 96 chan, publicSpectral Proc: 6-bit, <40MHz, 1024 chan, publicSpigot: 3-level, 50/800MHz, 1024/2048 chan, publicGASP: 8-bit, <100MHz, coherent dedisp, privateCGSR2: 2-bit, <100MHz, coherent dedisp, private

The only machines to give Full Stokes are GASP, CGSR2, and the Spectral Processor

GUPPI's Advantages

Searching: 800MHz of BW, 4096 chan, and RFI-resistance (from polyphase filterbank) will make GUPPI a “Super-Spigot” that will be unbeatable for searches from 1-5 GHz (previously the BCPM and Spigot)

High Dynamic-Range Studies: 8-bit sampling, high spectral resolution and Full Stokes will make GUPPI perfect for scintillation studies, HI absorption, Faraday rotation measurements, polarization studies, and singlepulse studies (previously the Spectral Processor)

Ultra-High Precision Timing: 8-bit sampling, 800MHz of BW, and RFI resistance will allow unprecedented timing precision from 1-3 GHz for millisecond pulsars (i.e. the NANOGrav project and the search for nHz gravitational waves; previously GASP/CGSR2)

GUPPI Team

• NRAO- CV– Paul Demorest, Ron Duplain, Rich Lacasse, Scott Ransom

• NRAO-GB– Patrick Brandt, Glen Langston, Randy McCullough, Jason

Ray

• Others– Casperites– Glenn Jones

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Original UC design

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GUPPI BEE2 signal processing chain

• Each 1.6 GS/s stream uses 1 FPGA for signal processing, 1 IBOB for data acquisition

• 4096 point PFB/FFT, with data streaming in and out, diagnostics in Block Ram

• Combines signals from each polarization, calculates stokes parameters, accumulates, and packages data, transmits over 10 Gb Ethernet to host.

• Minimum 50 microsecond accumulations• ~100 - 200 MB/sec data rate

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GUPPI iBOB Design

• Uses 1 ADC module and 2 10 Gbit XAUI links to digitize and transmit data streams to BEE2

• Has room for diagnostics, digital downconverter

Sampler

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GUPPI BEE2 signal processing design

• Each 1.6 GS/s stream uses 1 FPGA for signal processing

• 4096 point PFB/FFT, with data streaming in and out, diagnostics in Block Ram

Signal Processing

Xaui Alignment Block

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GUPPI BEE2 signal combining FPGA

• Combines signals from each polarization, calculates stokes parameters, accumulates, and packages data, transmits over 10 Gb Ethernet to host.

• Minimum 50 microsecond accumulations• ~100 MB/sec data rate

Signal combining/output

Controller

• core logic

• parameter exposure

• Data Acquisition interface

Data Acquisition

• data storage

• data quick look

• data status

Server

• Controller access

Client

• “external” interface

Demux

• common parameter access

• fully qualify parameter names

IBOB Interface

• parameter access

• (TinySH client)

(“Runs” on IBOB.)

BEE2 Interface

• parameter access

• (client-server)

(Runs on BEE2.)

The dashed box contains those modules which will run on GUPPI host, “beef.”

Software Connections

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User client module functions

• Simple command line interface• Allows users to set and get all parameter values• Allows users to start and stop FPGA processes• Python based, extensible with standard Python

functionality• Users can write/run their own scripts to control

observations• Client modules can be seamlessly integrated into GBT

M&C system, or any system that can open a connection to a Python SimpleXMLRPCServer

Hardware Parameters

• hardware designexcerpt (right)

• software register:

• BRAM:

GUPPI Command Prompt

• simple command prompt wrapped aroundPython interpreter

• tab completion for functions and parameter names• four basic functions:

– get and set for parameters– load and unload for FPGA profiles

Just add Python

• write simple scripts to build more functionse.g. use Python execfile

• import Python modules for extensibility• e.g. matplotlib (pylab) for plotting

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Data Acquisition Software

• Multi-threaded shared memory architecture• C program• Connects to 10 Gb Ethernet using UDP• Buffers data, provides quick-look functions• Streams data to disk in PSRFITS format• Handles 300 MB/S data stream with Myricom 10 Gb

Ethernet card, Tyan Motherboard, Opteron Processors and AMCC hardware RAID

• Interfaces to Python based controller through shared memory command buffer

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Portability and Extensibility

• Controller written in Python• Data Acquisition software written in C• Host is 64 bit Linux system, BEE2 runs 32 bit Linux

system• All connections to hardware are portable to

newer/different interfaces• All code written by NRAO staff GPL licensed

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First Light

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GUPPI Future Directions

• Add more diagnostics• Add other configurations, narrow bandwidths, more

channels, wider/narrower outputs, etc.• Add coherent dedispersion modes

– Long FFT's needed to implement inverse ISM filter– Possibly brute force better? Using convolution instead of FFT-

>Multiply->IFFT– Maybe better to stream out to computers for calculations.

• Make it robust enough to release for everyday use– Integrate with GBT observing system

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Conclusions

• Reconfigurable Computing platforms make for quick hardware development– GUPPI started in earnest in October, 2007. First light was in

April 2008.

• Standard software interfaces make for quick control interface development– The BEE2 and IBOB platforms use a common shell interface

to the FPGA parameter space, allowing for easy portability between all hardware subsystems

– Python for the development language allowed the power of the Python interpreter to be used to provide complex functions easily