A SOFTWARE DRM/DRM+ TRANSMITTER FOR GNU RADIO

1: Installation

2: Usage

3: Features

4: (Current) Constraints

5: Known Bugs

Dependencies: GNU Radio (min. v3.7), UHD, FAAC, FAAD2

For installation instructions for GNU Radio and UHD please visit GNUradio http://www.gnuradio.org (there is a build script making things really easy!).

• 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 ..
  

• FAAD2 (only needed for receiver)

    wget http://downloads.sourceforge.net/faac/faad2-2.7.tar.gz
    tar zxf faad2-2.7.tar.gz
    cd faad2-2.7
    . bootstrap
    ./configure --disable-shared --without-xmms --without-bmp --with-drm --without-mpeg4ip --with-pic
    make
    sudo cp include/faad.h include/neaacdec.h /usr/include
    sudo cp libfaad/.libs/libfaad.a /usr/local/lib
    cd ..
  

• gr-drm

    git clone git://github.com/kit-cel/gr-drm.git
    cd gr-drm/gr-drm
    git checkout stable
    mkdir build
    cd build
    cmake ../
    make
    make test # optional, all tests should pass!
    sudo make install
    sudo ldconfig
  

After successful installation of gr-drm, open the MLC flow graphs in gr-drm/hier_blocks with GNU Radio Companion and execute them in order to generate the appropriate XML and Python files that are used by the transmitter flow graphs.

You are now ready to transmit!

There are various, fully configured flow graphs under gr-drm/flow_graphs that can be used pretty much as-is. The DRM+ flow graph does not crash but is completely untested.

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

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 by simply adapting the correspondent blocks' values.

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)
• Reconfiguration

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

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

last updated on: 2014/01/11