GNU Radio A Free Software Defined Radio Eric Blossom Blossom Research Lighthouse Ave., Suite 109 Monterey, CA 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 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 Archive Open source hardware – –PCI bridges, ethernet, memory controllers, etc.

GNU Radio Questions?