DAB, la Germania piange. Gli inglesi no

Per una Germania che piange sulle macerie di un progetto DAB sostanzialmente fallito, la Gran Bretagna celebra una delle poche success story nel settore. Sembra che i dati sulle vendite di apparecchi DAB nel Natale scorso siano ottimi: oltre mezzo milione di radio vendute nel periodo delle feste, per una base installata che ormai conterebbe 6 milioni e mezzo di radio! Nel suo post Nick Piggott auspica un analogo potenziamento infrastrutturale. Molte radio vendute sono portatili e mobili e c'è bisogno di un segnale più intenso per assicurare un serfvizio decente a questo tipo di apparati. A un certo punto Nick sostiene addirittura che un impianto DAB deve "sparare" 10 kW per garantire la stessa qualità e la stessa copertura di un impianto FM da 1 kW. La minore efficienza sarebbe dovuta a due problemi: la perdita di segnale alle frequenze del DAB (e va bene) e i vincoli più laschi sui requisiti di sensibilità dei ricevitori. Nick chiede espressamente scusa ai tecnici per le sue approssimazioni, che anche a me paiono abbastanza azzardate. Non si fa cenno a quello che mi pare il problema più concreto: la qualità audio del DAB non-Plus e l'impossibilità, per quei 6,5 milioni e rotti di radio, di apprezzare i vantaggi di codifiche audio diverse.
Ma di fondo resta la solita questione: una storia di successo tra venti clamorosi flop deve spingere a essere ottimisti o pessimisti?

The DRDB reported another excellent Christmas for DAB Digital Radio sales, with 550,000 units sold, taking the cumulative total to 6.45m. The projections for this year put the total at over 8m come January 2009, and 30% of households using Digital Radio in some way or other.
The continued strong sales of DAB Digital Radios is all the more remarkable given that the UK retail sector generally had a lousy Christmas, and consumer sentiment towards discretionary purchases is pretty weak. Is this a sign that DAB is now established as the primary radio device, and no longer a special purchase?
The breakdown of sales is also interesting, with MP3/DAB Digital Radio combined devices rating well. It’s surprising when you consider that there aren’t that many MP3/DAB combination devices, that none of the major MP3 brands are making them, and that the convergence of MP3 and DAB functionality on those devices hasn’t exactly been stellar.
Handheld devices like these are more valuable to a mobile medium like radio than kitchen radios, but they do pose a particular challenge to broadcasters in providing robust enough signal strengths for them to work reliably. It can be done, but it needs a shuffle up of the existing network plans, which is going to be complicated. DAB still seems to be growing apace, and it would be disappointing if the growth of handheld DAB devices, which offer new functionality and genuine mobility, was held back because we were slow to deliver the right quality of signal to them.

To put some numbers on that challenge:

* A DAB transmitter needs to transmit 10kW of power to provide the same breadth and quality of reception on a device as an FM transmitter at 1kW (due to a combination of path loss at the different frequencies and a slightly lighter sensitivity requirement for DAB receivers)

* DAB is (currently) allocated only 7 frequencies, which means that nearly all DAB multiplexes are either adjacent (in frequency terms) to another multiplex in the same area, or on the same frequency as another multiplex nearby. That means there is far less elbow room for manoeuvre (currently) over transmission sites and powers.

These issues are resolvable, and the upturn in sales of handheld DAB devices should provide the impetus to start that difficult process.