1. GNU Radio A Free Software Defined Radio
Eric Blossom
Blossom Research
798 Lighthouse Ave., Suite 109
Monterey, CA USA

2. Thought for the day…
The milk of disruptive innovation doesn’t flow from cash-cows.
David S. Isenberg
GNU Radio

3. Overview Software defined radio Free (open source) software GNU Radio
Software ATSC receiver
GNU Radio

4. 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

5. 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

6. Disadvantages Higher power consumption than dedicated ASIC approach
More MIPS required
Higher cost (today)
GNU Radio

7. 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

8. Emerging SDR uses Personal communication devices
Cellular / Paging / Wireless LAN(s)
PC based “generic transceiver”
Radio / TV
Emerging unlicensed RF band apps
GNU Radio

9. 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.
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10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. GNU Radio resources Home page (links to source code) Mailing list
Mailing list
Archive
Open source hardware
PCI bridges, ethernet, memory controllers, etc.
GNU Radio

19. Questions?
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