1. Software Radio, GNU Radio, and
the USRP Product Family
Open Hardware for Software Radio
Matt Ettus, matt@ettus.com

2. Software Radio
 Simple, general-purpose hardware
 Do as much as possible in software
− Everyone's definition is different
 Continuum
 Everything Box vs. New Directions
 Dynamic Spectrum Management
 Cognitive Radio

3. GNU Radio
 A tool for rapid prototyping AND deployment
of software radios
 Free Software
 A platform for signal processing on
commodity hardware
 A platform for digital communications
research

4. GNU Radio Features
 Seamless Multithreading
 Easy to program, object-oriented interface
 Designs written in C++ or Python, a high-level language
 Extremely Fast
− DSP Primitives in C++ and often hand-coded SIMD
Assembly
 Built in standard signal-processing constructs
 GUI Integration
 Filter design
 Hides all memory, buffering, scheduling concerns
 Free software (GPL)

5. GNU Radio “Hello World”

6. GNU Radio Companion (GRC)

7. Achievements
 Large, diverse user community (>1000)
 Transmit and Receive many waveforms
− AM, FM, FM Stereo, TV, etc
− GMSK, PSK, OFDM, spread spectrum, etc.
− ATSC (HDTV) Transmitter and Receiver
 Highly Portable – same user code runs on
− Linux, Mac OS X, Windows, NetBSD
− X86 (32/64), PPC (32/64), Cell, ARM, OMAP

8. Universal Software Radio
Peripheral (USRP)
 Very Low Cost
 Open design / IP
 Interchangeable RF sections
 Wide bandwidth
 Extreme flexibility
 Beamforming/MIMO/Smart Antenna capable
 Large community
 Co-developed with GNU Radio

9. USRP

10. USRP Features
 Quad 64 MS/s 12-bit ADCs
 Quad 128 MS/s 14-bit DACs
 USB 2.0 Interface
− Handles 8 MHz of instantaneous, continuously
streaming RF Bandwidth at 16 bits per sample
 Low speed analog I/O for RSSI/gain control
 FPGA for high speed DSP ops
 2-Way MIMO “out of the box”
− 4-Way if using external RF frontends

11. Daughterboards
 BasicTX and BasicRX
− For use with external RF sections
− Flexible IF (0 to 200 MHz)
 LFRX and LFTX
− DC to 30 MHz
 TVRX
− 50-860 MHz receiver
 DBSRX
− 800 MHz – 2.4 GHz receiver

12. Transceiver Daughterboards
 RFX400 – 400-500 MHz transceiver, 100+mW output
 RFX900 -- 800-1000 MHz Transceiver, 250+ mW output
− Ham + ISM bands, modifiable for 1600-2000MHz
 RFX1200 -- 1150-1400 Mhz, 200+ mW output
− Ham, Satellite, Navigation bands
 RFX1800 -- 1500-2100 MHz, 250+ mW output
− PCS, Cell, DECT
 RFX2400 -- 50+ mW output, 2300-2800 Mhz
− Ham, ISM bands
 XVCR2450 – 50-250 mW output, 2.4-2.5GHz
and 4.8 to 5.9 GHz

13. New Transceiver
Daughterboards (coming in '09)
 50 MHz to 1 GHz Transceiver
 800 MHz to 2.2 GHz Transceiver
 Both are MIMO Capable, 100+ mW output

14. USRP applications
 Multi-Mbps GMSK, PSK, OFDM, MIMO networking
 MAC-layer development
 ZigBee, DECT, GSM, 802.11b
 Spectrum occupancy studies
 Cognitive Radio
 Active and Passive Radar
 SIGINT/COMINT
 Ham radio
 GPS (incl. multi-antenna receivers)
− http://www.gps-sdr.com
 RFID
 Mobile phone location and tracking
 Mobile phone base stations
− http://openbts.sf.net

15. USRP Applications, cont'd
 Dynamic Spectrum Access
 Over the horizon ship-tracking radar (port security)
 Public safety
− Linking multiple diverse radio systems
− In-building reliable firefighter communications
 Soldier in the field smart radios
 Wildlife tracking
 Medical imaging
 Teaching and student research
 Radio astronomy
 Security Research
 Satellite Ground Stations
 Project hosting at https://www.cgran.org/wiki/

16. Status
 Large, diverse user community
− About 3500 in use in 61 countries
− Academic, Commercial, Military
− Ham, Hobbyist, Radio Astronomy, SETI, etc.
 Many non-GNU Radio users
− SCA
 OSSIE from Virginia Tech
 SCARI from CRC
− Matlab/Simulink
− LabView
 Several Full-time GNU Radio/USRP
consultants
− Custom hardware, FPGA, and software design

17. USRP2 Features
 100 MS/s 14-bit dual (IQ) ADCs
− ~80 MHz instantaneous RF bandwidth
 400 MS/s 16-bit dual (IQ) DACs
 Gigabit Ethernet interface
− 3-6x improvement over USB
− Allows for 25 MHz of RF BW each way @16bits
 Wide enough for WiFi!

18. USRP2 Features, cont'd
 Bigger FPGA w/Multipliers (Spartan 3)
 1 MB high-speed on-board SRAM
 High speed serial expansion interface
 Configured by flash
− Can operate without host computer

19. USRP2 Features, cont'd
 External Frequency Reference Input
− Flexible choice of reference, not just 10 MHz
 Pulse per second (PPS) input for precise
timing
 Uses the same daughterboards as USRP1
− Only holds 1 TX and 1 RX
− MIMO via expansion interface
 Shipped in September 2008

20. USRP2 Layout

21. USRP2 PCB

22. USRP2

23. USRP2 FPGA
 Spartan 3
− ~40K logic cells, Lots of RAM and multipliers
 32-bit RISC Processor soft core
− 50 MHz
− GCC toolchain
 FIFOs and full crossbar between interfaces
− Aggregate 3.2 GBytes per second internal BW
− Very low latency
− Saturate GigE in both directions at once
 Precise timing control (10ns) for TDMA, etc.

24. USRP2 FPGA, cont'd
 Extensive use of Opencores.org
− Processor
− Wishbone Bus
− Interrupt controller, GPIO, SPI, I2C, UART
− Gigabit Ethernet MAC
− CPLD Flash bootstrap

25. WISHBONE Bus

26. Buffer Pool and Stream Interfaces

27. High-Speed Serial Link
 Four differential signals in each direction
− Carries data at 2 Gbps each way
− Reference clock for phase locking oscillators
− Time sync signal
− One high speed differential link available for user
 Network of USRP2 “Line Cards”
− Two USRP2s linked directly
− Four or more USRP2s linked by hub

28. High-Speed Serial Link, cont'd
 MIMO Applications
− Each USRP2 handles 1 antenna
− Everything is fully coherent to 1 master oscillator
 Low-cost industry-standard cabling
− Serial-attached SCSI (SAS)

29. Rack Mount (3U) Option

30. Resources
 Ettus Research LLC
− http://ettus.com
− matt@ettus.com
 GNU Radio Home Page
− Wiki, Source Code, Schematics, Mailing Lists
− http://gnuradio.org/trac
 External Project Hosting (CGRAN)
− https://www.cgran.org/wiki/