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Rapid Development of Rapid Development of Radio Astronomy Radio Astronomy
Instrumentation Using Instrumentation Using Open Source FPGA Boards, Open Source FPGA Boards,
Tools and LibrariesTools and Libraries
Center for Astronomy Signal Processing and Electronics ResearchCenter for Astronomy Signal Processing and Electronics Research
CASPER The Friendly...Group Helping Open-source Signal-Processing Technology? (GHOST)
✴ Goal is to Develop High Performance Signal Processing Infrastructure for the Astronomy Community and Beyond.
✴ Open Source Everything.
✴ Use Commodity Off-the-shelf Hardware Where Possible.
✴ Provide Training and Tutorials (Wiki, Video Lectures, Workshops etc...)
✴ Promote Collaboration (30+ Universities and Observatories.
✴ Do Not Necessarily Concentrate or Specialize in Turn-Key Instruments.
The Problem With The Current Hardware Development Model
✴Takes Five to Ten Years
✴Cost Dominated by NRE Because of Custom Boards, Backplanes and Protocols
✴Antiquated by the Time of Release
✴Each Observatory Designs From Scratch
Conventional Radio Astronomy Instrument Rack
Conventional Radio Astronomy Compute Board
Solution:✴ Low Number of Board
Designs
✴ Can be Upgraded Piecemeal or All Together
✴ Reusable
✴ Standard Signal Processing Model Consistent Between Upgrades
Modular Hardware
IBOB Board
BEE2 BoardRoach Board
Modular Gateware
✴ Gateware is the Design Logic of FPGAs (Between Hardware and Software)
✴ Signal Processing Libraries Which Do Not Need to be Rewritten Every Hardware Generation (FFTs, PFBs, DDC)
✴ Implement Industry Standard Communication Protocols (10 Gb Ethernet, UDP)
Platform-Independent Parameterized
Gateware
TransposerPFB/FFT
BufferIntegrator
ADC
iBOB
“Pocket Spectrometer”
What is an FPGA?✴ FPGA stands for Field
Programmable Gate Array - as the name implies, they consist of a collection of reprogrammable digital logic elements ✴ The first commercially
available FPGA was introduced in 1985.
✴ Common applications include telecommunications, cryptography, image processing, defense systems, etc..
What is an FPGA?✴ FPGAs are programmable logic
elements - bread-boards on a chip that can have their circuits reconfigured to perform specific tasks very efficiently.
✴ In addition to simple reconfigurable logic gates (AND, XOR, etc..) FPGAs often contain memory and dedicated multipliers.
Programming FPGAs
module addsub (a, b, addnsub, result);input [7:0] a;input [7:0] b;input addnsub;output [8:0]
result; reg [8:0] result; always @(a or b or
addnsub) begin if (addnsub)result = a + b;
else result = a - b;endendmodule
Conventional Method:Hardware Description Languages (HDL) - Verilog, VHDL
Conventional Method:Hardware Description Languages (HDL) - Verilog, VHDL
‣Adding and Subtracting in Verilog ‣Adding and Subtracting in C
x = a + b;
Programming FPGAsA Graphical Approach:A Graphical Approach:
The Leuschner Spectrometer
The Leuschner Spectrometer
Step 1:
Analog to Digital Conversion
In IDL:result=sampler(..)
Step 1:
Analog to Digital Conversion
In IDL:result=sampler(..)
The Leuschner Spectrometer
Step 2:
Channelization
In IDL:spectra=fft(..)
Step 2:
Channelization
In IDL:spectra=fft(..)
The Leuschner Spectrometer
Step 3:
Power and Accumulation
In IDL:result = total(..)
Step 3:
Power and Accumulation
In IDL:result = total(..)
Synthesis
Simulink
HDL Code
Place and Route
Binary FPGA Programming Instructions (Bitstream)
The “Compilation” Process
Download to IBOB
Leuschner Spectrometer System
IF at 150 MHz
100 Mbit Ethernet (UDP)
IDL “takespec”- receives UDP packets- stores payloads in raw binary format .log file
IDL “readspec”- opens and reads binary .log files- checks for dropped packets- converts to native IDL array
IDL “takespec”- receives UDP packets- stores payloads in raw binary format .log file
IDL “readspec”- opens and reads binary .log files- checks for dropped packets- converts to native IDL array
High-Res Spectrometers
4-input ‘Pocket’ Correlators
VLBI Channelizers
An 32-input Correlator:
16 iBOBs + 1 BEE2
An Arbitrary Sized Correlator:
Using a commercial switch we can solve the interconnect problem and enable highly scalable instruments.
A Beowulf Cluster for Radio Astronomy
The Fly’s EyeThe Fly’s EyeA Search for Highly Energetic Dispersed A Search for Highly Energetic Dispersed
Radio Transients using the Allen Radio Transients using the Allen Telescope ArrayTelescope Array
Fly’s Eye Motivation
Frequency vs. Time Waterfall (Lorimer 2007)
Exciting Results From Lorimer et al.
• Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, 2007.
Possible Sources of Bright Short-Duration Radio Pulses:
‣Evaporating primordial black holes‣Coalescing massive objects (NS-NS, NS-BH merger events)‣Emissions from cusps on cosmic strings‣ET‣RFI
Pulses of this type could serve as an invaluable cosmological probe of the intergalactic medium.
Fly’s Eye Timeline
‣November 19, 2007 - Dan Werthimer and Geoff Bower have lunch to discuss transient search projects using the ATA.
‣November 20, 2007 - A group of mostly undergraduate students to begin building a transient instrument.
‣December 22, 2007 - Fly’s Eye Team installs Fly’s Eye at ATA.
‣February, March 2008 - Conducted 500 hours of weekend observations.
‣April 2008 - Present - Data analysis underway
• Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, 2007.
September 27, 2007
• Fly’s Eye First Light
December 22, 2007
Fly’s Eye Basics44 independent spectrometers - constructed using a system of eleven iBOB/iADC quad spectrometers
Built using open-source CASPER hardware and software libraries in about one month.Sky Coverage:
22 - 42 beams100-200 square degrees
Spectrometer Specifications (each):208 MHz bandwidth, at 1430 MHz128 spectral channels0.625 mS readout
Distributions:Spatial, DM, Power, Pulse Width
Sky Coverage:22 - 42 beams100-200 square degrees
Spectrometer Specifications (each):208 MHz bandwidth, at 1430 MHz128 spectral channels0.625 mS readout
Distributions:Spatial, DM, Power, Pulse Width
Fly’s Eye Rack at ATA
Other Applications...VLBI Mark 5B Data Recorder - Haystack, NRAO
Transient Searches - Fly’s Eye at ATA - UC Berkeley and Cornell
Beamforming ATA & SMA - Weintroub, Urry, Milgrome et al.Oxford - Zarb-Adami et al.SETI:Arecibo - Werthimer, et al.JPL/UCB Deep Space Network - Levin et al.
Pulsar Timing and Searching:NRAO, Berkeley, Swinburne, Jodrell Bank et al.
Correlators and Imagers:ATA - Wright et al.EOR - Backer, Bradley, Parsons et al.CARMA Next Gen - Hawkins, Wright et al.MeerKAT/SKA South Africa - Jonas, Langman, et al.GMRT Next GenOthers....