Rapid Development of Radio Astronomy Instrumentation Using Open Source FPGA Boards, Tools and Libraries Center 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 Board Roach 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 Transpose r PFB/FFT Buffer Integrator 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 ✴ 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] or b or addnsub) beginif (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 FPGAs A Graphical Approach:

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 Eye A Search for Highly Energetic Dispersed Radio Transients using the Allen Telescope 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, 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, Dan Werthimer and Geoff Bower have lunch to discuss transient search projects using the ATA. ‣ November 20, A group of mostly undergraduate students to begin building a transient instrument. ‣ December 22, Fly’s Eye Team installs Fly’s Eye at ATA. ‣ February, March Conducted 500 hours of weekend observations. ‣ April Present - Data analysis underway Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, September 27, 2007 Fly’s Eye First Light December 22, 2007

Fly’s Eye Basics 44 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: beams square degrees Spectrometer Specifications (each): 208 MHz bandwidth, at 1430 MHz 128 spectral channels mS readout Distributions: Spatial, DM, Power, Pulse Width Sky Coverage: beams square degrees Spectrometer Specifications (each): 208 MHz bandwidth, at 1430 MHz 128 spectral channels 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 Gen Others....