April 8/9, 2003 Green Bank GBT 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.

2 Outline CICADA –Program organization –Assets –GUPPI Future directions

3 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.

4 CICADA Projects Spectrometers –KFPA backend –Replacement for GBT Spectrometer Event capture Pulsar machines –Incoherent machines Spigot replacement –Coherent dedispersion machines

5 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

6 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, public Spectral Proc: 6-bit, <40MHz, 1024 chan, public Spigot: 3-level, 50/800MHz, 1024/2048 chan, public GASP: 8-bit, <100MHz, coherent dedisp, private CGSR2: 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

10 Original UC design

11 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 ~ MB/sec data rate

12 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

14 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

17 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

20 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 design excerpt (right)‏ software register: BRAM:

GUPPI Command Prompt simple command prompt wrapped around Python 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 functions e.g. use Python execfile import Python modules for extensibility e.g. matplotlib (pylab) for plotting

24 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

25 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

26 First Light

27 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

28 Conclusions Reconfigurable Computing platforms make for quick hardware development –GUPPI started in earnest in October, First light was in April 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