dualword/librfsimulators

Library used to simulate an RF Digitizer

RF Simulators

This library may be used to simulate an RF Digitizer. At present, the RF Simulators library contains a single implementation; the FM RDS Simulator. While the RF Simulators library was designed to be used within the REDHAWK SDR environment, the library itself has no dependency on the REDHAWK framework and may be used as a stand alone C++ library.

Dependencies

• tinyxml
• libsndfile
• log4cxx
• fftw
• boost

Additional Build Time Dependencies

• autoconf
• automake
• libtool

Building & Installation

./reconf
./configure
make -j
sudo make install

Notes:

• You may need to modify the LD_LIBRARY_PATH environment variable, as is indicated in the output of the final installation step (sudo make install).
• Development packages of the dependencies are needed when building from source.
• See details below regarding required configuration files.

The FM RDS Simulator

The FM RDS Simulator will generate FM modulated mono or stereo audio with RDS encoded PI (Call Sign), PS (Short Text), and RT (Full Text) data. The code used to generate the RDS modulation leverages code developed for PiFmRds, the FM Modulation implementation is from GnuRadio, and the filtering classes from REDHAWKs dsplib and fftlib. Licensing / Copyright files can be found in the respective folders.

The simulator will provide complex samples at a maximum sample rate of 2.28 Msps. Supported sample rates must be integer multiples of this maximum rate (ex. 2.28Msps, 1.14Msps, 760Ksps etc) down to a minimum of 2.28Ksps.

Configuration Files

The FM RDS Simulator is initialized with a directory containing XML configuration files. The default and recommended location for these files is /usr/share/libFmRdsSimulator/examples. The configuration files must follow the following format:

<TxProps>
  <FileName>File_Name.wav</FileName>
  <CenterFrequency>104900000</CenterFrequency>
  <RDS>
    <CallSign>WSDR</CallSign>
    <ShortText>REDHAWK!</ShortText>
    <FullText>REDHAWK Radio, Rock the Hawk! (www.redhawksdr.org)</FullText>
  </RDS>
</TxProps>

Required fields are FileName and CenterFrequency. FileName is the relative path to the WAV audio file and CenterFrequency is specified in whole (integer) Hertz. RDS data is optional and will be filled in with default values if not provided. CallSign must be four characters and the ShortText cannot exceed eight characters.

A script generateConfigurationFiles.sh is included to help automate the generation of configuration files. Usage of the script requires a directory with one or more audio WAV files (with .wav extension) that will be accessible to the FM RDS Simulator.

Getting started & API Notes

The RF Simulator library has a fairly simple API currently. A factory pattern is used to instantiate the type of simulator and a user provided callback class is used for data delivery. All RF Simulators inherit from the RfSimulator class and the provided callback class must inherit from the CallbackInterface class. See the RfSimulator header for available methods and control.

Below is a trivial example which uses the RfSimulators namespace.

SampleCallback callback;

std::string p("/tmp/xmlFileLocation/");

RfSimulator * digSim = RfSimulatorFactory::createFmRdsSimulator();

digSim->init(p, &callback, TRACE);

digSim->start();

sleep(120);

delete(digSim);

Notes

The FmRdsSimulator creates a processing thread for each station within the currently visible 2.28 Mhz bandwidth (even if bandwidth is set smaller). Since each of these threads is resampling a wav file, FM modulating, encoding RDS, and upsampling to 2.28 Msps a non-trivial amount of CPU is used. Keep this in mind when distributing the FM Stations.

Copyrights

This work is protected by Copyright. Please refer to the Copyright File for updated copyright information. Copyrights and licenses for source from gnuradio, and PiFmRds are found in their respective folders within the src folder.

License

The RF Simulator Library is licensed under the GNU General Public License (GPL).