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Canada’s CHIME Radio Telescope generates 13Tbps as it scans the heavens—all processed by FPGAs in real time

by Xilinx Employee ‎09-14-2017 10:15 AM - edited ‎09-14-2017 10:53 AM (27,711 Views)


Earlier this month, the CHIME (Canadian Hydrogen Intensity Mapping Experiment) radio telescope came online and started scanning the universe at an intergalactic scale from the Dominion Radio Astrophysical Observatory in the heart of Canada’s wine country in British Columbia. The radio telescope is helping to generate a 3D map of the hydrogen distributed across the observable universe (the part that can be observed from the northern hemisphere anyway). CHIME has multiple missions including:



  • Map the history of the expansion rate of the Universe by observing hydrogen gas in distant galaxies that were very strongly affected by dark energy.


  • Detect FRBs (fast radio bursts) to act as an early warning system for the wider astrophysical community.


  • Monitor known pulsars in the Northern sky to investigate the properties of neutron stars and ionized gas in the interstellar medium to help verify the predictions of general relativity and the search for gravitational waves.



Other than electrons, the CHIME radio telescope has no moving parts. Instead, the telescope consists of four parallel, adjacent cylindrical cylinders measuring 20x100m and oriented north-to-south. The telescope scans the heavens as the Earth turns. CHIME’s four reflectors feed 256 focal-point antennas located along each cylindrical axis (for a total of 1024 antennas) and each antenna generates signal feeds from two polarizations for a total of 2048 signal feeds. CHIME’s front-end electronics then sample each signal at 800Msamples/sec, resulting in 1.6384 Tsamples/sec (that’s tera samples per second!), resulting in a front-end feed of 13Tbps.


CHIME needs some serious front-end processing to handle this torrent of input data and that processing occurs in a pair of FPGA-based “F-Engines,” which are housed in two shielded 20-foot shipping containers located adjacent to the cylindrical reflector array.


Here’s a photo of the CHIME reflector array and the F-engine containers:




CHIME Radio Telescope with F-Engine Containers.jpg 


CHIME Radio Telescope with F-Engine Containers




The F-Engines convert each μsec of raw input data (with 2048 samples/μsec) into a spectral representation spanning 400MHz to 800MHz with a frequency resolution of 0.39MHz. They bin the spectral data and ship the processed signals to a GPU-based “X-Engine” via optical fiber.


Here’s a simplified block diagram of the CHIME radio telescope:




CHIME Block Diagram.jpg 


CHIME Block Diagram




CHIME’s F-Engines use the FPGA-based “ICE” system developed by the McGill Cosmology Instrumentation Laboratory specifically for the CHIME radio telescope requirements and the requirements of the South Pole Telescope. The ICE system addresses the needs of these two radio telescopes by combining high-density DSP with high-bandwidth networking—two of an FPGA’s greatest strengths. The ICE system hardware consists of FPGA motherboards, application-specific daughter boards, and crates with custom backplanes.


The ICE motherboard incorporates two industry-standard FMC connectors (for the application-specific daughter boards) that connect to a Xilinx Kintex-7 FPGA. The Kintex-7 FPGA also provides the board with its twenty-eight 10Gbps serial ports for inter-board networking and data offload. An on-board ARM co-processor running Linux manages motherboard resources and allows users to quickly implement high-level algorithms in C or other popular programming languages.





CHIME ICE Motherboard.jpg 


The ICE motherboard incorporates a Kintex-7 FPGA connected to 16 ADCs mounted on the two FMC daughter cards





CHIME F Engine.jpg 


The CHIME F-Engine




If this all looks somewhat familiar, you may be one of the 19,000 people who have read the Xcell Daily post from 2014 that describes CHIME Pathfinder—a smaller, pilot version of the now-operational CHIME radio telescope. (See “FPGAs Aid Search for Dark Energy with CHIME Telescope” for considerably more technical information about the ICE-based F-Engine electronics.)







About the Author
  • Be sure to join the Xilinx LinkedIn group to get an update for every new Xcell Daily post! ******************** Steve Leibson is the Director of Strategic Marketing and Business Planning at Xilinx. He started as a system design engineer at HP in the early days of desktop computing, then switched to EDA at Cadnetix, and subsequently became a technical editor for EDN Magazine. He's served as Editor in Chief of EDN Magazine, Embedded Developers Journal, and Microprocessor Report. He has extensive experience in computing, microprocessors, microcontrollers, embedded systems design, design IP, EDA, and programmable logic.