DAB (Digital Audio Broadcast) is one of the standard used to broadcast radio using digital encoding. Aside form audio, DAB permits the transmission of multimedia / applicative contents, such as images slideshow, traffic information, news and so on.
Audio encoding is based on MPEG-2 codec for legacy DAB and AAC+ for DAB+.
CSP has developed a system able to build a full DAB+ trasmission chian; basic components are:
- AAC audio encoder (including insertion of ancillary data – slideshow and DLS)
- ETI muxer
- IQ modulator
- RF modulator
- a simple GUI to control all the components
AAC audio encoder and Ancillary Data Transmission
The system is based on the library of the Fraunhofer FDK AAC code from Android, patched for 960-transform to do DAB encoding. CSP had a primary role in the open source evolution of FDK AAC concerning the encoding of DAB applicative data inside AAC samples (PAD – Programme Associated Data). In particular CSP has developeB+ broadcast encoding. Opendigitalradio now maintains an updated version targeted for DAB applications.
of MOT-Slideshow and DLS: the former permits the transmission of pictures associated to the audio and the latter permits to send a descriptive text shown by the display of the radio.
This software has been merged to the Opendigitalradio. You can download the lates version from git https://github.com/Opendigitalradio/fdk-aac-dabplus
ETI Muxer and IQ Modulator
Latest version is avaiable on git https://github.com/Opendigitalradio
This components developed by CSP and based on GNURadio use the USRP 1 Ettus board to broadcast the RF signal. It supports both VHF and L bands