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GNU Radio A Free Software Defined Radio Eric Blossom eb@comsec.com Blossom Rese

GNU Radio A Free Software Defined Radio Eric Blossom eb@comsec.com Blossom Research +1 831 917 3428 798 Lighthouse Ave., Suite 109 Monterey, CA 93940 USA GNU Radio Thought for the day… The milk of disruptive innovation doesn’t flow from cash-cows. – David S. Isenberg GNU Radio Overview Software defined radio Free (open source) software GNU Radio Software ATSC receiver GNU Radio What is software defined radio? Get the software close to the antenna Software defines the waveforms Replace analog signal processing with digital signal processing GNU Radio Why SDR? Flexibility Quicker time to market Multiple personalities (chameleon) New things are possible: – Multiple channels at the same time – Better spectrum utilization – “Cognitive radios” GNU Radio Disadvantages Higher power consumption than dedicated ASIC approach More MIPS required Higher cost (today) GNU Radio Current SDR users Military – Consolidating a stack of radios – Bridging between radio networks Cellular base stations – Avoid “fork lift upgrades” – Multiple standards on same system – New features to market quicker GNU Radio Emerging SDR uses Personal communication devices – Cellular / Paging / Wireless LAN(s) PC based “generic transceiver” – Radio / TV – Emerging unlicensed RF band apps GNU Radio What is “free software?” “Free as in liberty” – User has access to the source – User is free to modify and is encouraged to contribute the modifications back to the community A culture of innovation Various licenses: GNU General Public License (GPL), Mozilla, Artistic License. GNU Radio Who uses free software? World wide community of users Publicly traded companies support or distribute free software: IBM, Red Hat, Mandrake Linux Apache web server Not a fringe activity GNU Radio What is GNU Radio? It’s a free software defined radio A platform for experimenting with digital communications A platform for signal processing on commodity hardware GNU Radio Vision Transmit and receive any signal Create a practical environment for experimentation & product delivery Expand the “free software ethic” into what were previously hardware intensive arenas GNU Radio What H/W is required? Commodity PC RF front end (e.g., TV tuner module) Multi-channel applications / wide B/W: – High speed A/D (20 – 25 Msamples/sec) Single channel / narrow bandwidth: – SoundBlaster, AC97 codec, etc. GNU Radio SDR ATSC receiver is practical! Commodity PC: – Dual processor Athlon 1800+ MP – 512 MB RAM / 120 GB disk – $1300 – Can do: • 6 * 10^9 integer ops / sec • 4 * 10^9 FIR filter taps / sec GNU Radio ATSC computational requirements 1080i TSP decode takes about ½ of a single CPU Naïve equalizer: about 2.5 * 10^9 taps/s – Smart s/w version: about 0.6 * 10^9 taps/s Viterbi decoder: 10^6 decisions / sec. – Highly amenable to SIMD implementation – Short constraint length GNU Radio Moore’s Law is on our side Even if we’re off by a little bit, within 3 years we’ll have 4 times the performance for the same money. General purpose hardware gets faster by itself (Intel, AMD, etc take care of it). ASICs don’t get faster by themselves. – Even a die shrink is expensive & time consuming GNU Radio Open source hardware too! General purpose SDR PCI peripheral: – Tuner module $20 – 25 Msample/sec A/D converter $12 – Spartan II FPGA (100k gates) $18 – Misc analog, SRAM, etc $10 – PWB $10 – Assembly & Test $10 Total cost to manufacture: $80 GNU Radio GNU Radio resources Home page (links to source code) http://www.gnu.org/software/gnuradio Mailing list discuss-gnuradio-request@gnu.org Archive http://mail.gnu.org/mailman/listinfo/discuss-gnuradio Open source hardware – http://www.opencores.org/projects/pci – PCI bridges, ethernet, memory controllers, etc. GNU Radio Questions? uploads/Science et Technologie/ gnuradio-guide.pdf