The ODR mmbTools Open-Source DAB Transmission Chain

The DAB+ transmission chain composed of ODR-DabMux and ODR-DabMod and the Ettus Research USRP software-defined radio platform is a very interesting, flexible and cheap 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.

Developement 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

A guide for these tools is also in preparation, it is not complete yet. The sources of the guide are also 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 transmitters.

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.