1. GNU Radio Jiewen Huang 1/31/2011

2. 2 Outline  What is GNU Radio?  Basic Concepts  Developing Applications  HW2 Introduction

3. What is GNU Radio?  Software toolkit for signal processing  Software radio construction  Rapid development  USRP (Universal Software Radio Peripheral)  Hardware frontend for sending and receiving waveforms

4. GNU Radio Components Hardware Frontend Host Computer RF Frontend (Daugtherboard) ADC/DAC and Digital Frontend (USRP) http://mobiledevices.kom.aau.dk/fileadmin/mobiledevices/teaching/software_testing/Gnu_radio_lecture.pdf GNU Radio Software

5. GNU Radio Software  Opensource software (GPL)  Don't know how something works? Take a look!  Existing examples: 802.11b(Wi-Fi), ATSC (HDTV), OFDM, DBPSK, DQPSK  Features  Extensive library of signal processing blocks (C++/ and assembly)  Python environment for composing blocks (flow graph)

6. GNU Radio Hardware  Sends/receives waveforms  USRP Features  USB 2.0 interface (480Mbps)  FPGA (customizable)  64Msps Digital to Analog converters  128Msps Analog to Digital converteres  Daughterboards for different frequency ranges  Available Daughterboard  400-500Mhz, 800-1000Mhz, 1150-1450Mhz, 1.5-2.1Ghz, 2.3-2.9Ghz

7. GNU Radio Hardware Schematic RX/TX Daughterboar d ADC/DAC http://mobiledevices.kom.aau.dk/fileadmin/mobiledevices/teaching/software_testing/Gnu_radio_lecture.pdf Host Computer FPGA USB Interface

8. 8 Outline  What is GNU Radio?  Basic Concepts  Developing Applications  HW2 Introduction

9. Basics: Blocks  Signal Processing Block  Accepts 0 or more input streams  Produces 0 or more output streams  Source: No input  noise_source, signal_source, usrp_source  Sink: No outputs  audio_alsa_sink, usrp_sink

10. Basics: Data Streams  Blocks operate on streams of data 153 379 412

11. Basics: Data Types  Blocks operate on certain data types  char, short, int, float, complex  Vectors  Input Signature:  Data types for input streams  Output Signature:  Data types for output streams Two streams of float One stream of complex

12. Basics: Flow Graph  Blocks composed as a flow graph  Data stream flowing from sources to sinks

13. Example: OFDM Synchronizer http://gnuradio.org/trac/raw-attachment/wiki/Wireless/gr_ofdm.pdf

14. GNU Radio Companion

15. GNU Radio Companion (Cont'd)  GNU Radio Companion  Design flow graphs graphically  Generate runnable code  Demonstration

16. 16 Outline  What is GNU Radio?  Basic Concepts  Developing Applications  HW2 Introduction

17. Development Architecture http://mobiledevices.kom.aau.dk/fileadmin/mobiledevices/teaching/software_testing/Gnu_radio_lecture.pdf Python Application development Flow graph construction C++ Signal processing blocks  Python  Application management (e.g., GUI)  Flow graph construction  Non-streaming code (e.g., MAC-layer)  C++  Signal processing blocks  Certain routines also coded in assembly Why is the hybrid structure?

18. Dial Tone Example #!/usr/bin/env python from gnuradio import gr from gnuradio import audio from gnuradio.eng_option import eng_option from optparse import OptionParser class my_top_block(gr.top_block): def __init__(self): gr.top_block.__init__(self) parser = OptionParser(option_class=eng_option) parser.add_option("-O", "--audio-output", type="string", default="", help="pcm output device name. E.g., hw:0,0") parser.add_option("-r", "--sample-rate", type="eng_float", default=48000, help="set sample rate to RATE (48000)") (options, args) = parser.parse_args () if len(args) != 0: parser.print_help() raise SystemExit, 1 sample_rate = int(options.sample_rate) ampl = 0.1 src0 = gr.sig_source_f (sample_rate, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sample_rate, gr.GR_SIN_WAVE, 440, ampl) dst = audio.sink (sample_rate, options.audio_output) self.connect (src0, (dst, 0)) self.connect (src1, (dst, 1)) if __name__ == '__main__': try: my_top_block().run() except KeyboardInterrupt: pass

19. Dial Tone Example (1) from gnuradio import gr from gnuradio import audio from gnuradio.eng_option import eng_option from optparse import OptionParser Import modules from GNU Radio library

20. Dial Tone Example (2) class my_top_block(gr.top_block): def __init__(self): gr.top_block.__init__(self) Define container for Flow Graph; gr.top_block class maintains the graph

21. Dial Tone Example (3) parser = OptionParser(option_class=eng_option) parser.add_option("-O", "--audio-output", type="string", default="", help="pcm output device name. E.g., hw:0,0") parser.add_option("-r", "--sample-rate", type="eng_float", default=48000, help="set sample rate to RATE (48000)") (options, args) = parser.parse_args () if len(args) != 0: parser.print_help() raise SystemExit, 1 Define and parse command-line options

22. Dial Tone Example (4) sample_rate = int(options.sample_rate) ampl = 0.1 src0 = gr.sig_source_f (sample_rate, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sample_rate, gr.GR_SIN_WAVE, 440, ampl) dst = audio.sink (sample_rate, options.audio_output) self.connect (src0, (dst, 0)) self.connect (src1, (dst, 1)) Create and connect signal processing blocks

23. Dial Tone Example (5) if __name__ == '__main__': try: my_top_block().run() except KeyboardInterrupt: pass Run the flow graph when the program is executed

24. Creating Your Own Block  Basics  A block is a C++ class  Typically derived from gr_block or gr_sync_block class  Three components  my_block_xx.h : Block definition  my_block_xx.cc : Block implementation  my_block_xx.i : Python bindings (SWIG interface)

25. Block Definition #include class my_block_cc; typedef boost::shared_ptr cs434_my_block_cc_sptr; cs434_my_block_cc_sptr cs434_make_my_block_cc(); class my_block_cc : public gr_sync_block { private: unsigned int d_count; friend cs434_my_block_cc_sptr cs434_make_my_block_cc(); cs434_my_block_cc(); public: int work(int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items); }; Create instances of block Method for processing input streams and producing output streams

26. Block Implementation (1) #ifdef HAVE_CONFIG_H #include "config.h" #endif #include cs434_my_block_cc_sptr cs434_make_my_block_cc() { return cs434_my_block_cc_sptr(new cs434_my_block_cc()); } cs434_my_block_cc::cs434_my_block_cc() : gr_sync_block("my_block_cc", gr_make_io_signature(1, 1, sizeof(gr_complex)), gr_make_io_signature(1, 1, sizeof(gr_complex))), d_count(0) { } Helper method to create block Define input and output signatures

27. Block Implementation (2) int cs434_my_block_cc::work(int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items) { const gr_complex* in = (const gr_complex*)input_items[0]; gr_complex* out = (gr_complex*)output_items[0]; memcpy(out, in, sizeof(*out) * noutput_items); for (int i = 0; i < noutput_items; ++i) fprintf(stderr, "%u\t \n", d_count++, in[i].real(), in[i].imag()); return noutput_items; } Copy input stream to output stream Return number of items processed Echo samples stderr

28. SWIG Interface GR_SWIG_BLOCK_MAGIC(cs434, my_block_cc); cs434_my_block_cc_sptr cs434_make_my_block_cc(); class cs434_my_block_cc : public gr_sync_block { private: cs434_my_block_cc(); }; Condensed copy of block definition (in header file)

29. 29 Outline  What is GNU Radio?  Basic Concepts  Developing Applications  HW2 Introduction

30. HW2 Overview  Implement MAC layer for a wireless device  Link-layer header  Carrier-sensing and backoff  Link-layer acknowledgments  Template code at  https://www-net.cs.yale.edu/svn/courses/cs434/spring09/hw4/gr-cs434-hw4/

31. Useful Links  Homepage (download, more links, etc)  http://gnuradio.org/trac/  More comprehensive tutorial  http://gnuradio.org/trac/wiki/Tutorials/WritePythonApplications  Available Signal Processing Blocks  http://gnuradio.org/doc/doxygen/hierarchy.html  GNU Radio Mailing List Archives  http://www.gnu.org/software/gnuradio/mailinglists.html  CGRAN: 3 rd Party GNU Radio Apps  https://www.cgran.org/  OFDM Implementation Presentation  http://gnuradio.org/trac/wiki/Wireless