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Lo Spectrum del DRM

L’autorevolissima rivista Spectrum, organo ufficiale della principale associazione ingegneristica mondiale ha pubblicato sul numero di ottobre un interessante articolo sul DRM


da Radio Passioni
L’autorevolissima rivista Spectrum, organo ufficiale della principale associazione ingegneristica mondiale ha pubblicato sul numero di ottobre un interessante articolo sul DRM (“tecnologia nata morta o che deve ancora nascere?”) e sui ritardi che irrimediabilmente seguono agli annunci di disponibilità dei ricevitori. L’altro giorno Andrea Borgnino, reduce di una riunione organizzata in Italia, da Rai e altri operatori, sul tema (Andrea ha promesso un reportage), mi diceva piuttosto stupito che tra i partecipanti circolava la convinzione che i primi apparecchi saranno disponibili… A fine 2007. Spectrum accusa gli europei di tentennare su sistema di radio digitale che rischia di fare la fine fatta dal DAB in molte nazioni.

Nel frattempo, l’altro Andrea, Russo, mi avverte che sul forum del gruppo di programmatori del software DReaM è comparso un messaggio che prevede la disponibilità di un piccolo quantitativo di ricevitori DRM Himalaya (già commentati su RP dall’IFA) già entro fine 2006. Penso di scrivere due righe agli amici di Himalaya incontrati all’evento berlinese e farvi sapere qualcosa. Resta il fatto che questa benedetta tecnologia, ormai sperimentata a mani basse sulle onde medie di mezza Europa (e anche mezza basta quanto a rumore digitale che si riversa sulle povere stazioni analogiche), non la può sentire nessuno. D’accordo, i broadcaster devono sperimentare cose come le soglie minime di ricevibilità per un segnale che sotto una certa soglia di rapporto S/N (segnale/rumore) non può essere decodificato al 100%. A questo proposito ho letto su un recente numero di DXLD, il 6146, di un articolo che Donald Messer, capo del technical committee del DRM ha pubblicato su RW Online (il titolo, eloquente, recita: “I ricevitori DRM arrivano rapidamente sul mercato”. Rapidamente?). Nelle applicazioni locali del DRM, sui 26 MHz, la qualità audio garantita da una decodifica al 100% sarebbe possibile, secondo Messer, già a soglie di rapporto S/N tra i 15 e i 20 dB, assai più favorevoli, in teoria, dei 30 dB necessari per un buon audio analogico sulle onde medie. Messer non sarà eccessivamente ottimista? Un lungo studio del Fraunhofer Institut relativo ai test sui 26 MHz in Germania dicono che le soglie di piena comprensibilità del signale digitale si collocano intorno ai 23-26 dB (uV/m). Certo che sta diventando un bella saga…

Europe Dithers Over Digital Radio
By: Michael Dumiak

It’s been a year since Digital Radio Mondiale was supposed to spark a revolution. Shiny new radios would come fitted with DRM technology to receive a new, higher-­quality digital signal for shortwave and AM broadcasting. That in turn would pave the way for all-digital airwaves—first in Europe, and then in Asia, Latin America, and North America.
It never happened. The first DRM receivers were supposed to be on the market in time for last December’s holiday shopping [see photo, “Stocking Stuffer]. But because of unspecified technical glitches—or maybe just cold feet on the part of manufacturers, who worried about whether the technology would truly take off—stores still lack radios. Now, with this year’s holiday season fast approaching, DRM backers are trying to drum up enthusiasm for the technology.
DRM got its start a decade ago in the R&D labs of the United Kingdom’s BBC, Germany’s Deutsche Welle and Deutsche Telekom, and the United States’ Jet Propulsion Laboratory and Voice of America. The idea was to develop a nonproprietary digital technology for ­terrestrial broadcasting at frequencies of 30 megahertz and below, to supplement the satellite transmission technologies already in place [see sidebar, “Roll Over, Marconi”]. Although analog shortwave signals can travel many thousands of miles, reception is easily disrupted and tends to be spotty. Analog AM fidelity is generally better than that of shortwave, but broadcast reach is much smaller, except at night, when signals bounce off the ionosphere.
Among the advantages of digital broadcasting are its consistency of signal quality and its efficiency. A 50-kilowatt transmitter using DRM can reach Warsaw from London, while an analog transmitter with the same reach would have to be 200 kW, observes the BBC’s John Sykes, a DRM pioneer. Not surprisingly, dozens of major international broadcasters are backing DRM, which also lets them get out of analog shortwave broadcasting without leaving its bandwidth fallow. “Radio will be digital. Full stop,” says Peter Senger, a longtime R&D man at Deutsche Welle and leader of the international Digital Radio Mondiale consortium.
But for DRM to take hold, listeners will have to go out and buy new radios, and so far that’s put a full stop to DRM. Why would people throw out perfectly good radios and plunk down the equivalent of US $200 to buy supposedly better ones, considering they can already get all the content they want with their existing sets?
Sony Corp. and Blaupunkt, both part of the DRM consortium, show no signs of putting a DRM-compatible radio on the market, and they declined to offer comments for this story. Evidently, for now they’d rather leave the field to more obscure manufacturers, such as Taiwan’s Sangean Electronics and Britain’s Roberts and Morphy Richards. No company has yet offered consumers a DRM car radio. Still, “pilot production runs are happening as we speak,” says Dave Hawkins, a business development strategist at RadioScape, in London, which makes the decoding module for DRM receivers. Hawkins is confident that radios will be available for Europe’s Christmas holiday market this year.
There are tense days ahead, though. DRM boosters express confidence that when consumers hear it, they’ll like it. They say that even though DRM’s sound quality will not be like hearing true hi-fi, listeners will appreciate having shortwave and AM stations coming in at near-FM quality. Even more important, perhaps, listeners will be able to get many more stations than before, and if they purchase a well-equipped radio, they will have user-friendly ways of identifying and selecting programs of interest. But Sangean, Roberts, and Morphy Richards don’t have the marketing clout of a Sony, and rarely does a new technology sell itself.

Roll Over, Marconi: New Digital Technologies Occupy Radio Space

HD Radio: A proprietary digital radio system, HD is the government-approved industry standard in the United States for local-area broadcast. It is promoted by iBiquity Digital Corp., in Columbia, Md., which was originally backed by Lucent Technologies and broadcasters CBS and Gannett Co. HD uses in-band on-channel (IBOC) transmission, which means digital signals use sidebands and can be piggybacked on existing analog broadcasts, so stations can stick with existing frequency allocations and simulcast analog and digital programming if they wish. Broadcasters using the HD system get a cheap upgrade to the transmitter but pay license fees to iBiquity. Nine car brands, including BMW, offer HD Radio as a factory-installed option.
Digital Radio Mondiale: DRM is an open-standard digital radio system for broadcasting on AM and shortwave bands that requires a DRM-compatible receiver. It is backed by a large consortium of international broadcasters, including the BBC World Service, Deutsche Welle, and Radio France, as well as manufacturers such as Blaupunkt, Bosch, Panasonic, Sony, and Texas Instruments.
But the radios are not available yet and will cost between US $150 and $300 when they are. Satellite: Listeners pay a roughly $12-per-month subscription fee, and commercial-free shows featuring hosts such as Howard Stern and Bob Dylan are beamed from satellites to home or car receivers. XM Satellite Radio and Sirius Satellite Radio operate in North America; WorldSpace Satellite Radio serves Europe, Africa, and Asia. A home for uncensored, cutting-edge, and specialized content, XM and Sirius have 4 million subscribers between them, and lately there’s been talk of a merger. Digital Audio Broadcasting: Promoted by the World DAB Forum, DAB is broadcasting on FM bands using the Eureka 147 standard, adopted by Europe, Canada, and Asia. To date, some 1.3 million DAB radios have been sold in the United Kingdom at about $100 and up.—M.D.

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