Transcript GNU Radio A Free Software Defined Radio

GNU Radio
A Free Software Defined Radio
Eric Blossom
[email protected]
Blossom Research
798 Lighthouse Ave., Suite 109
Monterey, CA 93940 USA
+1 831 917 3428
Thought for the day…
The milk of disruptive
innovation doesn’t flow from
cash-cows.
– David S. Isenberg
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Overview
Software defined radio
 Free (open source) software
 GNU Radio
 Software ATSC receiver
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What is software defined radio?
Get the software close to the antenna
 Software defines the waveforms
 Replace analog signal processing with
digital signal processing
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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”
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Disadvantages
Higher power consumption than
dedicated ASIC approach
 More MIPS required
 Higher cost (today)
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Current SDR users

Military
– Consolidating a stack of radios
– Bridging between radio networks
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Cellular base stations
– Avoid “fork lift upgrades”
– Multiple standards on same system
– New features to market quicker
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Emerging SDR uses
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Personal communication devices
– Cellular / Paging / Wireless LAN(s)
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PC based “generic transceiver”
– Radio / TV
– Emerging unlicensed RF band apps
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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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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
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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
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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
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What H/W is required?
Commodity PC
 RF front end (e.g., TV tuner module)
 Multi-channel applications / wide B/W:
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– High speed A/D (20 – 25 Msamples/sec)
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Single channel / narrow bandwidth:
– SoundBlaster, AC97 codec, etc.
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SDR ATSC receiver is practical!
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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
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ATSC computational
requirements
1080i TSP decode takes about ½ of a
single CPU
 Naïve equalizer: about 2.5 * 10^9 taps/s
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– Smart s/w version: about 0.6 * 10^9 taps/s
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Viterbi decoder: 10^6 decisions / sec.
– Highly amenable to SIMD implementation
– Short constraint length
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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.
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– Even a die shrink is expensive & time
consuming
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Open source hardware too!
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General purpose SDR PCI peripheral:
– Tuner module
– 25 Msample/sec A/D converter
– Spartan II FPGA (100k gates)
– Misc analog, SRAM, etc
– PWB
– Assembly & Test

Total cost to manufacture:
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$20
$12
$18
$10
$10
$10
$80
GNU Radio resources
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Home page (links to source code)
http://www.gnu.org/software/gnuradio
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Mailing list
[email protected]
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Archive
http://mail.gnu.org/mailman/listinfo/discuss-gnuradio
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Open source hardware
– http://www.opencores.org/projects/pci
– PCI bridges, ethernet, memory controllers, etc.
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Questions?
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