The ODR mmbTools Open-Source DAB Transmission Chain

The DAB+ transmission chain composed of ODR-DabMux and ODR-DabMod and the Ettus Research USRP or LimeSDR software-defined radio platforms is a very interesting, flexible and low-cost way to set up a DAB+ transmitter. An encoder for DAB and DAB+ is available on ODR-AudioEnc. ODR-PadEnc can encode DLS and Slideshow as Programme Associated Data.

Simplified DAB+ transmission chain with two audio programs.

Simplified DAB+ transmission chain with two audio programs.

The ODR-mmbTools are a fork of the CRC-mmbTools whose development has ceased. Opendigitalradio pursues this development, and takes care to create a set of tools that are ready for production environments.

Development is done with a focus on:

  • Robustness: make sure the tools are reliable and can cope with uncommon situations
  • Control: give the multiplex operator control over his network
  • Flexibility: each programme originator shall have his own encoder
  • Features: develop new functionality, protocols, interconnects, etc.

Guide

The guide gives an introduction in the tools through step-by-step instructions. The sources of the guide are on github.

The tools themselves are:

ODR-DabMux implements a DAB multiplexer that combines all audio and data
inputs into an ETI output. It can be used off-line (i.e. not real-time) to generate
ETI data for later processing, or in a real-time streaming scenario (e.g. in a
transmitter).

ODR-DabMod is a software-defined DAB modulator that receives or reads ETI,
and generates modulated I/Q data usable for transmission. It can directly interface the Ettus USRP devices, and can also be used with other SDR signal sources.

ODR-AudioEnc contains a MPEG-1 Layer II audio encoder that is used to encode audio for the DAB standard and uses fdk-aac to encode for DAB+.

ODR-PadEnc can read DLS from a text file and slides from a folder, and prepare the PAD data stream for injection into the audio encoder.

The tools can be easily installed on a debian stable system following the install script. It is also possible to install the tools using the PyBOMBS recipes contributed by David Lutton. The release tarballs are available here.

Help needed

The tools are under continuous development. Opendigitalradio welcomes new ideas and contributions. If you are interested in contributing to and improving a broadcasting tool-set that is used in 24/7 production internationally, please do get in touch with us! Each project contains a TODO file with ideas for improvements:
ODR-DabMux TODO
ODR-DabMod TODO
ODR-AudioEnc TODO