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
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.
For installation instructions for GNU Radio and UHD please visit GNU Radio (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 ..
-
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
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. After generating,
you need to restart GRC or to click the "reload" button.
You are now ready to transmit!
There are various, fully configured flow graphs under apps/drm_tx_grc
that can be used pretty much as-is. Robustness Mode B with Spectrum Occupancy 3 (10 kHz)
is the most popular mode and is also tested against the Newstar DR111 DRM Receiver.
Other modes may work, too. 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
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 correspondant blocks' values. Please note that not every combination of Robustness mode and Spectrum Occupancy is valid.
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)
- 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: felix.wunsch[at]kit.edu
last updated on: 2016/08/08