La ratio dietro questa migrazione: consentire a tutte le stazioni AM di adottare la modulazione digitale di HD Radio senza provocare interferenze reciproche. La proposta è stata presentata nel quadro dei commenti richiesti dalla FCC (Docket 07-294) in merito ai cambiamenti che faranno seguito allo spegnimento della tv analogica negli USA. Mi limito ad osservare che ovviamente nessuno degli attuali ricevitori HD Radio per l'FM copre quella porzione di spettro, toccherebbe buttar via le radio o acquistare scomodi convertitori. Senza contare del terribile effetto marketing su oggetti - i ricevitori HD Radio appunto - ancora poco conosciuti dal grande pubblico. Una simile proposta rischierebbe di rallentare ulteriormente l'adizione di HD Radio, perché molti consumatori potrebbero anche decidere di attendere i prossimi sviluppi per acquistare una radio non in grado di sintonizzarsi sulle stazioni migrate dall'AM. A certe cose i "consulenti" non ci pensano.
Engineers’ Group Has an Idea: Move AMs to Channels 5 & 6
It’s a dramatic idea that would change infrastructure reaching back to the very roots of our industry.
A group made up primarily of broadcast consulting engineers proposes a new use for TV Channels 5 and 6 in the United States once their occupants migrate to digital. It recommends the reallocation of part of that spectrum for the use of the country’s AM stations.
The group, calling itself the Broadcast Maximization Committee, recommends the conversion and migration of all AM stations over an extended period of time and with digital transmissions only.
It also proposes relocating the LPFM service to a portion of this spectrum and expanding the NCE service into the adjacent portion.
The group made its proposal in a filing to the FCC as part of the broadcast diversity proceeding (Docket 07-294). Comments in that proceeding were due this week. Other organizations also have used the proceeding to discuss how the radio spectrum should be structured; but these comments are likely to draw new attention to the plight of AM stations and possible ways to help the occupants of the senior band.
Engineering Consultant John Mullaney, a proponent of using Channels 5 and 6 for radio, is part of BMC. Noting that similar proposals to use that space for radio stations have been dismissed by the commission as premature until the DTV transmission is done, the group says the time is ripe for this proposal.
Although LPFMs and NCE stations would benefit, AMs would gain the most, the group contends. The proposal would move virtually all AM stations to the new band.
The engineers lay out a plan under which all or most of the current AM occupants would move and parts of the existing band would be designated for users like municipalities and LPAM stations.
“For clear-channel (Class A) AM stations we are proposing that the FCC will increase existing protections on the AM band and possibly re-allocate the Class As that stay in such a way that they will have enough protection from other AM stations so that they can operate HD Radio day and night without creating interference,” BMC member Bert Goldman told Radio World.
“This reduction in AM noise will allow the remaining Class A stations to increase their daytime and nighttime interference-free service by removing all other AM stations.”
Each channel is anticipated to be structured in such a way that the station may decide if they want greater robustness of signal (and greater coverage like in rural locations) or less robustness and up to four program channels. BMC is not proposing a digital standard at this time.
BMC has also proposed a way to move the estimated 24 post-transition DTV stations out of Channels 5 and 6.
The proposal is signed by Mullaney, Goldman, Mark Lipp, Paul H. Reynolds, Joseph Davis, Clarence Beverage, Laura Mizrahi, Lee Reynolds and Alex Walsh.
More details of the migration idea are here.