Introduction To GNU Radio

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaGNU radio naming convention Words in identifiers are separated by underscores (e.g.gr vector int) All types begin by gr (e.g. gr float) All class variable begin by d (e.g. d min stream) Each C class is implemented in a separated file (e.g. classgr magic implemented in file gr magic.cc with header filegr magic.h) All signal processing blocs contain their input and output types intheir suffixes. e.g.:dc blocker ff impl.ccdc blocker cc impl.cc[.][.]dc blocker ff impl::dc blocker cc impl::dc blocker cc impl(int D, bool longdc blocker ff impl(int D, bool long form): sync block("dc blocker cc",: sync block("dc blocker ff",io signature::make (1, 1, sizeof(gr complex)),io signature::make (1, 1, sizeof(float)),io signature::make (1, 1, sizeof(gr complex))),io signature::make (1, 1, sizeof(float))),d length(D), d long form(long form)d length(D), d long form(long form)Tanguy RissetIntroduction to GNU Radio22

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaBlock signature A bloc signature is a specification of the data types that enter orexit the bloc. There are always two bloc signatures, one for inputs, the otherfor outputs. Each bloc signature specifies the number and types of ports. excerpt from gr io signature.h:class GR RUNTIME API io signature{intd min streams;intd max streams;std::vector int d sizeof stream item;io signature(int min streams, int max streams,const std::vector int &sizeof stream items);public:typedef boost::shared ptr io signature sptr; io signature();static sptr make(int min streams, int max streams,int sizeof stream item);/*!* \brief Create an i/o signature*Tanguy RissetIntroduction to GNU Radio* \ingroup internal23

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaBoost Pointer Gnu radio uses Boost smart pointers. Boost is a software library that provides a smart implementationof C pointers that offers garbage collection (i.e. delete objectnot used anymore). Gnu radio uses only the shared ptr type of Boost Instead of declaring a pointer to a type X:X* myPointer;you can declare:boost::shared ptr X myBoostPointer example in gr io signaturetypedef boost::shared ptr io signature sptr;static sptr make(int min streams, int max streams,int sizeof stream item);Tanguy RissetIntroduction to GNU Radio24

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaVolk library Gnu radio uses VOLK (which stands for Vector-Optimized Libraryof Kernels) volk provides a number of optimized function for vectorprocessing using SIMD instructions. Developing with volk might be tricky because it is sensible toalignment of vector in memory. Understanding code using volk simply requires to understandvolk naming convention: The basic naming scheme will look something like this:volk (inputs params) [name] (output params) [alignment] example:volk 32f invsqrt 32fTanguy RissetIntroduction to GNU Radio25

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaOther Volk example General naming convention when there are several inputs oroutputs:volk (input type 0) x(input num 0) (input type 1) x(input num 1) .[name] (output type 0) x(output num 0) (output type 1) x(output num 1) . [alignment] Examples: Multiply two complex float vectors together (aligned and unalignedversions) and the dispatcher:volk 32fc x2 multiply 32fc avolk 32fc x2 multiply 32fc uvolk 32fc x2 multiply 32fc Add four unsigned short vectors together:volk 16u x4 add 16u Multiply a complex float vector by a short integer:volk 32fc s16i multiply 32fcTanguy RissetIntroduction to GNU Radio26

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaSWIG SWIG is a software development tool that connects programswritten in C and C with a variety of high-level programminglanguages. SWIG is used in GNU Radio to link Python and C codeTanguy RissetIntroduction to GNU Radio27

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaSWIG in brief write a C file example.c code that defines the fact function. write an interface file for SWIG:%module example%{extern int fact(int n);%} execute the swig command: unix % swig -python example.i it generates a example wrap.c Compile it:unix % gcc -c example.c example wrap.c-I/usr/include/python2.7unix % ld -shared example.o example wrap.o -o example.so use it in python: import example example.fact(5)120Tanguy RissetIntroduction to GNU Radio28

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating GNU radio modules A gnu radio module newModule corresponds to a directorynewModule should contain the following directories:CMakeLists.txt docs grc include lib python swig the gr modtool tool helps you create the various directory Hence the flow for creating a block in a module Create the module file hierarchy with gr modtool Create a block in the module with gr modtool Edit the C file to code the module functionalities Test, debug and validate the functionalitiesTanguy RissetIntroduction to GNU Radio29

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating a trivial module: module creation creating the module directory structure: gr modtool newmodarith Go into the new directory: cd gr-arith cd gr-arith/ lsapps CMakeLists.txt examples includecmake docsgrclibTanguy RissetIntroduction to GNU RadioMANIFEST.mdpythonswig30

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating a trivial module: adding a bloc create a general block in the module (answer to questions):gr modtool add -t general times2 create a python test method: edit python/qa times2.py update python/CMakeLists.txt (nothing to do here) create the build directory cd .;mkdir build; build the project: cd build; cmake ./Tanguy RissetIntroduction to GNU Radio31

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating a trivial module: directory hierarchygr-arith[.] -- CMakeLists.txt -- docs -- CMakeLists.txt -- doxygen -- CMakeLists.txt[.] -- grc -- arith times2.xml -- CMakeLists.txt -- include -- arith -- api.h -- CMakeLists.txt -- times2.h -- lib -- CMakeLists.txt -- qa arith.cc -- qa arith.h -- qa times2.cc -- qa times2.h -- test arith.cc -- times2 impl.cc -- times2 impl.cc -- times2 impl.h -- python -- CMakeLists.txt -- init .py -- qa times2.py -- qa times2.py Tanguy RissetIntroduction to GNU Radio32

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating a trivial module: The C part Header files are in include/times2 directory Code is in lib/times2 impl.cc, edit it and replace the by values. in times2 impl() (constructor in forecast (indicate scheduler how many input are requires forhow many output items) in general work core of the treatment. make it (in the build directory), and make testTanguy RissetIntroduction to GNU Radio33

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating a trivial module: debugging use printf (#include sdtio.h ) use make; make test (from python testbench: not infinite) log output in Testing/Temporary/LastTest.logTanguy RissetIntroduction to GNU Radio34

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating a trivial module: debugging Now that you have written a valid block, you can create a validgrc block (in gr-arith directory, gr modtool makexml times2 install it: cd build; sudo make install create a simple grc application (use throttle, remove printf) run it (warning: no print!)Tanguy RissetIntroduction to GNU Radio35

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaUsing gr modtool for a sync module creation gr modtool newmod fmrds gr modtool add -t sync div16 (heritates from gr sync block,no forecast method). edit python/qa div16.py edit lib/qa div16.ccTanguy RissetIntroduction to GNU Radio36

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaCreating a sync blockgr modtool add -t sync div16GNU Radio module name identified: fmrdsLanguage: C Block/code identifier: div16Enter valid argument list, including default arguments:Add Python QA code? [Y/n]Add C QA code? [y/N]Adding file 'div16 impl.h'.Adding file 'div16 impl.cc'.Adding file 'div16.h'.Editing swig/fmrds swig.i.Adding file 'qa div16.py'.Editing python/CMakeLists.txt.Adding file 'fmrds div16.xml'.Editing grc/CMakeLists.txt.Tanguy RissetIntroduction to GNU Radio37

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaWriting a test for the div16 blockfrom gnuradio import gr, gr unittestimport fmrds swig as fmrdsclass qa div16 (gr unittest.TestCase):def setUp (self):self.tb gr.top block ()def tearDown (self):self.tb Nonedef test 001 t (self):# set up fgself.tb.run ()# check dataTanguy RissetIntroduction to GNU Radio38

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaWriting the C core of div16Edit lib/div16 impl.cc[.]div16 impl::div16 impl(): gr::sync block("div16",gr::io signature::make( MIN IN , MAX IN , sizeof( ITYPE )),gr::io signature::make( MIN OUT , MAX OUT , sizeof( OTYPE ))){}[.]intdiv16 impl::work(int noutput items,gr vector const void star &input items,gr vector void star &output items){const ITYPE *in (const ITYPE *) input items[0]; OTYPE *out ( OTYPE *) output items[0];// Do signal processing }// Tell runtime system how many output items we produced.return noutput items;Tanguy RissetIntroduction to GNU Radio39

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaNext stageLabs: write an audio filter bloc in GNU radioTanguy RissetIntroduction to GNU Radio40

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaTable of Contents1Introduction to Gnu radio2GNU radio with gnuradio-companion3Creating Gnu radio blocksCoding conventionBoost, Volk ad SwigCreating a trivial GNU radio module: square signalCreating a sync bloc: div164Block behavior and Schedulergeneral worksync blocks5Message passing interfacePMTMetadataTags & MessagesTanguy RissetIntroduction to GNU Radio41

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaBlock important function Each Gnu radio bloc inherits from the gr block class. The gr block class contains the following important function (file GNURADIO/include/gnuradio:void set history(unsigned history);virtual void forecast(int noutput tems,gr vector int &ninput items required);virtual int general work(int noutput items,gr vector int &ninput items,gr vector const void star &input items,gr vector void star &output items);void consume(int which input, int how many items);Tanguy RissetIntroduction to GNU Radio42

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler Messafunction general work The general work() function computes output streams frominput streams It has 4 arguments int noutput items Number of output items to write on each outputstream (all output streams must produce the same number ofoutput). int ninput items[] Number of input items to read in each inputstream void* intput items[] Vectors of pointers to elements of the inputstream(s), i.e., element i of this vector points to the i th input stream. void* output items[] Vectors of pointers to elements of the outputstream(s), i.e., element i of this vector points to the i th output stream.Tanguy RissetIntroduction to GNU Radio43

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler Messafunction general work The general work function implement the signal processingalgorithm. It is called by the scheduler (implicitly, i.e. you do not have toinvoke this function explicitly) The consume function indicates to the scheduler how many datahave been consumed once the general work has been executed Use of input items and output items vectors:input items[0][0]input items[0][1]General Blockoutput items[0][0]output items[0][1]data.data.data.input items[1][0]Tanguy RissetIntroduction to GNU Radio44

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaOne execution of the block Before executioninput items[0][0]input items[0][1]General Blockdata.A6 A5 A4 A3 A2 A1noutput items 1data.output items[0][0]ninput items[0] 4ninput items[1] 2data.C1B3 B2 B1input items[1][0] after executioninput items[0][0]input items[0][1]General Blockdata.A6 A5noutput items 1data.output items[0][0]ninput items[0] 4ninput items[1] 2data.C1B3input items[1][0]Tanguy RissetIntroduction to GNU Radio45

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaWhat the code of work function could be Example: sum the 6 samples in input on the outputfor(unsigned int j 0; j 4; j ) {output items[0][0] input items[0][j];}for(unsigned int j 0; j 2; j ) {output items[0][0] input items[1][j];} But it is not that simple. Gnu radio scheduler invokes the work function for computing achunks of output (i.e. not one output by one output, in order toavoid too many context switches) noutput item stays symbolic, it will be set dynamically duringthe execution by the scheduler for performance optimization(usually between 4000 and 10000).Tanguy RissetIntroduction to GNU Radio46

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaWhat the code of work function should be add one loop over all noutput items output samples:for (i 0; i noutput items; i ) {for(j 0 ; j 4; j ) {output items[0][i] input items[0][4*i j];}for(unsigned int j 0; j 2; j ) {output items[0][i] input items[1][2*i j];}} Remember to avoid as much as possible samples copy.Tanguy RissetIntroduction to GNU Radio47

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler MessaWhat the code of work function really is Usual Gnu radio way of writing:const gr complex *in1 (const gr complex*)input items[0];const gr complex *in2 (const gr complex*)input items[1];gr complex *out (gr complex*)output items[0];for (i 0; i noutput items; i ) {for(j 0 ; j 4; j ) {*out *in1 ;}for(unsigned int j 0; j 2; j ) {*out *in2 ;}*out ;}Tanguy RissetIntroduction to GNU Radio48

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler Messaforecast function forecast() is a function which tells the scheduler how manyinput items are required to produce noutput items output items. In most of the case, they are the same:voidmy general block::forecast (int noutput items,gr vector int &ninput items required{ninput items required[0] noutput items;} It is used as an information by the scheduler to schedule theexecutions of the different blocs so as to prevent starvation orbuffer overflows.Tanguy RissetIntroduction to GNU Radio49

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler Messaconsume function The consume (int which input, int how many items)function tells the scheduler that how many items of input streamwhich input were consumed. This function should be called at the end of general work(),after all processing is finished consume each (int how many items) can be used it thenumber of items to consume is the same on each input streamsTanguy RissetIntroduction to GNU Radio50

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocksBlock behavior and Scheduler Messasummary: code for my general block{my general block::general work (int noutput items,gr vector int &ninput items,gr vector const void star &input items,gr vector void star &output items)const gr complex *in1 (const gr complex*)input items[0];const gr complex *in2 (const gr complex*)input items[1];gr complex *out (gr complex*)output items[0];for (i 0; i noutput items; i ) {for(j 0 ; j 4; j ) {*out *in1 ;}for(unsigned int j 0; j 2; j ) {*out *in2 ;}*out ;}consume(0,4*noutput items);consume(2,4*noutput items);}voidmy general block::forecast (int noutput items,gr vector int &ninput items required){}ninput items required[0] 4*noutput items;ninput items required[1] 2*noutput ite

Introduction to Gnu radio GNU radio with gnuradio-companion Creating Gnu radio blocks Block behavior and Scheduler Message passing interface Table of contents . Debugged (with spectrum analyzer for instance) Tanguy Risset Introduction to GNU Radio 13.File Size: 1MB