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

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 S/W controlled conventional radio S/W controlled digital demod (ASICs, etc) S/W baseband modulation / demodulation S/W channel selection, up/down conversion, filtering, mod/demod 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 Cellular base stations 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) Mailing list 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? GNU Radio