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GR-DRM

A SOFTWARE DRM/DRM+ TRANSMITTER FOR GNU RADIO

Contents

1: Installation

2: Usage

3: Features

4: (Current) Constraints

5: Known Bugs

Installation

Dependencies: GNU Radio (min. v3.7), UHD, FAAC

From Source (automated)

If you're using a recent version of the popular linux distributions, pybombs is probably the way to go:

git clone --recursive https://github.com/pybombs/pybombs.git
cd pybombs
./pybombs install gr-drm

and answering all the questions to best knowledge (the defaults are sane); you might need to later call

./pybombs env

to generate a file that you can source <filename> in your .bashrc or .zshenv.

From Source (manual)

For installation instructions for GNU Radio and UHD please visit GNU Radio (there is a build script making things really easy!). The instructions assume that you don't want to install into your home folder. If that's the case, adjust the prefixes accordingly.

  • FAAC

      wget http://downloads.sourceforge.net/faac/faac-1.28.tar.gz
  tar zxf faac-1.28.tar.gz
  cd faac-1.28
  . bootstrap
  ./configure --with-pic --disable-shared --without-mp4v2 --enable-drm
  make
  sudo cp include/faaccfg.h  include/faac.h /usr/include
  sudo cp libfaac/.libs/libfaac.a /usr/local/lib
  cd ..

  • gr-drm

      git clone git://github.com/kit-cel/gr-drm.git
  cd gr-drm
  mkdir build
  cd build
  cmake ../
  make
  make test # optional, all tests should pass!
  sudo make install # sudo is only needed if you don't install to your home folder
  sudo ldconfig

Usage

After successful installation of gr-drm, you can either use the flow graph in apps/grc_flowgraph or the GUI in apps/gui. The DRM+ flow graph is completely untested due to the lack of a receiver.

Of course you have to set the path to your USRP (or leave it blank for autodetection) and a source wav-file (either 12 or 24 kHz). There are also several other parameters you can change (see section Features). It is also possible to record a wav-file that can be decoded with DREAM.

As wav files usually aren't sampled with 12 or 24 kHz, I use sox for convenient resampling. Syntax: sox <mysong.wav> -r <new_sample_rate> <mysongresampled.wav> resample

Features

This project features a DRM/DRM+ software transmitter fully integrated into GNU Radio Companion.

You are also free to play around with several robustness modes (RM) and spectrum occupancies (SO, signal bandwidth) ranging from 4.5 to 20 kHz. The corresponding bit rates vary from below 5 kbps to about 55 kbps. A configuration that is widely used is RM B (==1) and 10 kHz bandwidth (SO 3). Among other parameters, the station label and a text message can also be set. Please note that not every combination of Robustness mode and Spectrum Occupancy is valid.

(Current) Constraints

As this project is still under development, there are some features of the DRM standard that are not (yet) available. The most important are:

  • Unequal Error Protection (UEP)
  • Hierarchical mapping (HMsym and HMmix)
  • multiple audio/data streams (currently only one audio stream in AAC Mono (no SBR) is possible)

Known Bugs

  • text message corrupted for SO 5 / RM A (and possibly other modes)

If you find any bugs or have ideas you think the project could benefit from, just write me: felix.wunsch[at]kit.edu

last updated on: 2016/10/08