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Linux, SETI, and Radio Astronomy Marcus Leech Radio Science Laboratories

Linux, SETI, and Radio Astronomy Marcus Leech Radio Science Laboratories http://www.radio-science-labs.com. Image appears courtesy NRAO/AUI. What is Radio Astronomy?. Astronomy at wavelengths from a few mm to tens of meters

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Linux, SETI, and Radio Astronomy Marcus Leech Radio Science Laboratories

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  1. Linux, SETI, and Radio Astronomy Marcus Leech Radio Science Laboratories http://www.radio-science-labs.com Image appears courtesy NRAO/AUI

  2. What is Radio Astronomy? • Astronomy at wavelengths from a few mm to tens of meters • Visible light has wavelengths in the region of 500nm, that is, 5.0x10-7 meters • From a physics standpoint, there's no difference between visible light, and microwave/radio-wave “light”. • Living things have receptors for only a tiny part of the EM spectrum

  3. Optical vs Radio Astronomy • Ability to resolve fine detail highly dependent on wavelength • A 10cm optical telescope can resolve details that would require a radio telescope over 42km in diameter at 21cm wavelength! • Sensitivity, however, is proportional to collecting area of the reflector, regardless of wavelength • Both use parabolic reflectors • Both must have a surface that is within 1/10th of wavelength of perfect for maximum efficiency.

  4. History of Radio Astronomy • Like much in science, it was discovered accidentally • Karl Jansky, 1933, working on sources of static on international radio-telephone circuits at wavelengths of 10-20M. • Discovered that static rose and fell with a period of 23 hours, 56 minutes. • Must be of celestial origin

  5. The Genesis of Radio Astronomy Science • Jansky was re-assigned to other projects after his work on radio-telephone “hiss”. • Several years went by with nobody understanding the significance of his discovery • Grote Reber picked up on Janskys work in 1937, building a 30ft dish in his back yard. • Eventually mapped entire Milky Way emission at 160Mhz (1.8M wavelength)‏ • Published in Astrophysical Journal in 1944 • Radio Astronomy now taken seriously

  6. Grote Rebers Dish • Now preserved as historical artefact at NRAO, Green Bank, West Virginia

  7. Radio Astronomy Today • Radio Astronomy at the cutting-edge of astrophysical research • Roughly 70% of what we know today about the universe and its dynamics is due to radio astronomy observations, rather than optical observations • Big projects all over the world • VLA, New Mexico • Arecibo, Puerto Rico • GBT, Green Bank, West Virginia • Westerbork, Jodrell Bank, ALMA, Hat Creek, SKA, etc • Scientists named the basic flux unit after Karl Jansky • 1 Jansky == 10-26 watts/hz/meter2

  8. SETI • Drake equation: • N = R* x Fp * Ne x Fl x Fi x Fc x L • N number of potential ET civilizations • R* rate of star formation • Fraction of stellar systems with planets • Ne fraction planets that can support life • Fl fraction that actually produce life • Fi Fraction that develop intelligent life • Fc fraction that develop detectable technologies (radio, etc)‏ • L length of time such civilizations emit (lifetime)‏

  9. SETI contd • Many observing programs over the years • Harvard: META and BETA • SERENDIP I/II • NASA: HRMS • Cancelled after only 1 year by senator Richard Bryan • “This hopefully will be the end of Martian hunting season at taxpayers expense” • Was a comparatively-small NASA program • Personnel went on to form the SETI Institute • SETI@Home -- using data gathered mostly at Arecibo

  10. SETI Science/Engineering • Look for narrowband (~1Hz wide) signals coming from “out there”. • Eliminate terrestrial sources (interference, etc)‏ • See if signals have appropriate doppler drift (chirp)‏ • Do they fit the profile of the antenna pattern? • Need for wideband, high-resolution spectrometers • Usually done in ASIC implementing high-speed FFT • SDR can play a role

  11. Gnu Radio, SDR, Linux • SDR Software Defined Radio • Software to replace traditional hardware functions • FAST A/D and D/A hardware • REALLY FAST compute platforms • GNU Radio • Open Source toolkit for SDR • Cost-effective (like, free) solution for experimental RF/Microwave work.

  12. SDR Hardware • Provides basic RF interface • High-speed A/D and D/A • down/upconversion to/from baseband signals • Some digital filtering • Many hardware platforms • USRP Universal Software Radio Peripheral • http://www.ettus.com • Beefy gamers-class PC platform: Q6600 3.5GHz, 8GB memory

  13. SDR RA/SETI Software • Developed gr-radio-astronomy subtree of Gnu Radio • Provides basic RA and SETI tools • Open Source • New IRA software: • Fully integrated RA/SETI receive chain • SETI up to 16Million 1Hz channels • Pulsar, Total Power, Spectral, Transients • http://www.science-radio-labs.com

  14. GNU Radio Development Tools • Python and C++ can be used to assemble so-called flow graphs. • Signal processing chain • GRC • Graphical tool to generate flow-graphs, using MATLAB/LabView like interface.

  15. Example GRC flow graph

  16. Flowgraphs and GUIs • Lots of different applications built with GNU Radio and various GUI toolkits. • All-mode HF transceiver • RADAR • GPS • Radio Astronomy

  17. Gnu Radio Application example

  18. IRA Software • RA/SETI all-mode receiver • Based on XFORMs toolkit • Talks to flowgraph through FIFOs

  19. IRA Main Panel

  20. IRA SETI Waterfall

  21. IRA Spectral

  22. IRA Pulsar

  23. IRA Continuum

  24. IRA Interferometer

  25. Typical Total-Power observation • Sagittarius A in Total Power • Combined multi-day observations

  26. An exciting new project • 18M dish at Shirleys Bay • Needs lots of work • SBRAC consortium formed to renovate/operate for amateur RA and SETI

  27. Further reading • Society of Amateur Radio Astronomers • http://www.radio-astronomy.org • “Radio Astronomy Projects, 3rd ed”, William Lonc • http://www.radiosky.com • National Radio Astronomy Observatory • http://www.nrao.edu • http://www.cv.nrao.edu/course/astr534/ERA.shtml • Radio Jove Project • http://radiojove.gsfc.nasa.gov

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