Digital radio broadcasting in various iterations has been with us for nearly 15 years, but among those countries that originally launched Eureka 147 DAB systems early on, only the UK has persevered with much of its original DAB architecture still intact, including its original MPEG Layer II coding technology.
During the decade and a half since digital radio's shaky debut, improvements to the Eureka 147 technology family such as DAB+ now seem to be paying off, as a new wave of rollouts takes place across Europe and elsewhere. Even so, glimpses into what goes into making a digital transition at a practical level remain rare. That's why a recent report on the state of Sweden's DAB+ pilot project issued by government-owned broadcast service group Terracom makes especially interesting reading for those interested in the digital radio adoption process.
Based on a 2008 government recommendation, Sweden is well into pilot testing of DAB+ via a VHF band III multiplex network supported from transmitter sites located in the cities of Upsala and Gavle, as well as in the capital, Stockholm, where three sites are in operation. All the above multiplexes have been in operation for two years or more, and actual field measurements are being correlated with predictive coverage software to verify its accuracy.
In order to evaluate system performance from a variety of perspectives, both Layer II and AACv2 are being used at a variety of bit rates from 48 to 112kb/s. Various program associated data (PAD) rates are also under evaluation, as are the transmission of slide show graphics. Terracom's report also delves into some of the techniques and architecture being used to generate and distribute the DAB+ signals to their respective multiplex transmission points.
Content offered on the multiplexes now includes four channels from public broadcaster Swedish Radio along with four channels from commercial radio group MTG. Local community and commercial broadcasters along with a couple of webcasters also contribute to a total channel load of up to 15 channels.
Several commercially available DAB+ receivers are also being used in the evaluation process, including Pure's futuristic Sensia.
The report concludes by highlighting areas for further research and welcoming public input on the trials.