ODR-mmbTools SFN enters production

After several weeks of tests we are delighted to announce the first production deployment of the ODR-mmbTools in Single Frequency Network operation. The SFN consists of two overlapping co-channel transmitters serving part of the city of London. The multiplex is operated by U.DAB.

The multiplex launched on the 28th of October carrying a mix of local, community and online broadcasters and is one of ten DAB trials licensed by Ofcom—the UK communications regulator.

This achievement is the result of an international collaboration. Rashid Mustapha (Senior Broadcast Specialist at Ofcom and Open Digital Radio partner) has worked closely with both U.DAB and the ODR development team in Switzerland to realise the trials. Development of SFN in the ODR-mmbTools started in 2012 in a student master thesis with CRC in Canada, EPFL and EBU (see master thesis report). It has been continously improved since then to make it stable for continuous operation and has been working in lab environment but had never been used in production.
Rashid stated that one of the main objectives of these trials is to validate the Open Source tools with third party hardware in order to provide an affordable way for smaller radio services to broadcast on the digital radio platform. The difference in this trial, and a second imminently launching in Glasgow, Scotland is the use of the Open Digital Radio GPSDO circuit design. The unit designed by lead developer Matthias Brändli is an open source design based on the u-blox LEA-M8F GPS, GLONASS and BeiDou receiver module. The PCB is designed for the Ettus Research B200 SDR peripheral, and needs only an external GPS aerial, and a patched version of the Ettus UHD driver.

This cost effective SFN solution should help local DAB broadcasters to complete coverage using low power transmitters.

Channel Impulse Response measurement of SFN network

Channel Impulse Response measurement of SFN network

ODR-mmbTools is set of free open source software tools that can be composed together to form an entirely free and open-source DAB/DAB+ transmission chain. These tools are currently developped and maintained by the non-profit organisation Opendigitalradio. For more information please join the mailing list or contact: broadcast@opendigitalradio.org