Scusa, ti disturbo la frequenza?

Radio Passioni confronta le problematiche interferenziali italiane con l’esperienza USA


da Radio Passioni

Mi piace imparare nuove cose sul modo in cui le nazioni veramente civilizzate regolamentano una risorsa condivisa preziosa come lo spettro delle radiofrequenze attraverso la applicazione pragmatica ma flessibile di regolamenti equilibrati (e rispettati da tutti! mica come accade qui, nella provincia dell’allegra alegalità), sperimentazione, approfondita discussione tra le parti e delibere trasparenti, subito convertite in nuove regole equilibrate.
Quando le imparo, l’Italia dello spettro radio mi appare sempre più come il paese delle occasioni mancate, delle opportunità bruciate sul nascere da questa nostra perversa tendenza a dare spazio (e magari voti elettorali) a cento inutili e parassitari furbetti dei quartierini piuttosto che a milioni di cittadini meritevoli. Ehi, c’è un nuovo sistema di radio digitale, lo proviamo? E come si fa? Non c’è spazio visto che Radio Insuccessi Italiani occupa una frequenza (non sua) troppo vicina Radio Rumore International a sua volta costretta a usare otto megawatt perché troppo vicina a Radio Maddalena.
L’11 settembre l’FCC americana ha pubblicato una sorta di request for comment avviando la procedura che definirà il funzionamento di dispositivi non licenziati – cioè di uso libero una volta ricevuta l’omologazione (tipo il Wi-Fi, quello che ci abbiamo messo 42 anni ad approvare) – nella banda di frequenze televisive liberate dai broadcaster che nel 2009 passeranno al digitale. Leggetevi le due paginette riportate qui di seguito insieme a un breve commento-notizia del Washington Post. Sembra di assistere a un dibattito tra extraterrestri. La FCC aveva avuto la stessa idea nel 2004, ma non se n’era fatto niente perché la mancata chiarezza su alcune tecnicalità aveva portato a discussioni non risolvibili e al temporaneo accantonamento della proposta. In sostanza la FCC dice: realizziamo degli apparati in grado di posizionarsi o di essere in qualche modo indirizzati su un canale che in quel momento, nell’area geografica occupata, non viene utilizzato da nessuno. Nel 2004 si pensava per esempio che l’apparecchio in questione potesse essere dotato di un sistema di geolocalizzazione GPS e che potesse interrogare a distanza un database di frequenze libere. Database costituito a sua volta dagli altri apparecchi interessati a quella stessa porzione di frequenze, che avrebbero dovuto segnalare il fatto di essere, in un dato momento, spenti. Un principio di “best effort” neanche troppo innovativo, sperimentato con successo da Bob Metcalfe per l’invenzione dello standard di rete Ethernet (sapete che la rete Ethernet è nata perché Bob aveva copiato un sistema di ponti radio a pacchetto creato da radioamatori per collegare le diverse sedi dell’Università delle Hawaii? La rete, ovviamente, si chiamava Aloha). Ripreso in tante applicazioni come i sistemi a frequency hopping o nei moderni apparati di comunicazione militare ALE (automatic link establishment) e sviluppato ultimamente nella cosiddetta cognitive radio di cui anche Radiopassioni ha parlato. Ora la FCC rilancia questo argomento con l’obiettivo di stabilire una nuova normativa per l’uso non licenziato delle ex frequenze televisive entro il 2007 e avere prodotti finali entro il 2009
La fonte da cui ho ricavato il documento della FCC, la newsletter The CGC Communicator, di Robert Gonsett chiude la notizia affermando: “la nostra previsione è che entro pochi anni l’uso delle frequenze radio sarà, generalmente, condiviso”. In altre parole non ci saranno più bande rigidamente allocate, ma ampi porzioni di spettro in cui diversi servizi e dispositivi potranno convivere senza interferirsi a vicenda sulla base di un galateo digitale/telematico che consentirà loro di usare la o le frequenze che in quel momento nessun altro componente di questa “società di dispositivi” sta occupando. “Scusi, posso trasmettere su 853 MHz?”, “No guardi, si sposti su 854, ma fino alle 15, perché dopo dovrà scendere a 852”. “Ah, grazie, aspetti che lo dico ai miei televisori”. Bello, eh? Secondo il Washington Post (sì, quello che con i suoi articoli faceva cadere i presidenti americani; da noi sono i presidenti che fanno cadere gli articoli, i giornalisti e magari, se gli garba, l’intero giornale), aziende come Intel starebbero facendo una lobby sfrenata per uno scenario di questo tipo. Anche perché evidentemente apparecchi così sofisticati ed elastici dovranno avere a bordo un bel po’ di intelligenza di silicio. Ma non vi preoccupate, prima di vedere cose del genere dalle nostre parti passeranno ancora due o tre secoli.

Office of Engineering and Technology Announces Projected Schedule for Proceeding on Unlicensed Operation in the TV Broadcast Bands

ET Docket No. 04-186

On May 13, 2004, the Commission adopted a Notice of Proposed Rule Making (“Notice”) proposing to allow the operation of unlicensed devices on TV channels that are unused at any given location. This public notice establishes a schedule for resolving outstanding issues in that proceeding so that unlicensed devices designed to operate on unused TV frequencies may be placed on the market with the completion of the DTV transition.
The Notice proposed to require that fixed unlicensed devices incorporate a geo-location method such as GPS or be professionally installed, and that they access a database to identify vacant channels at their location. It proposed to require that portable unlicensed devices operate only when they receive a control signal from a source such as an FM or TV station that identifies the vacant TV channels in that particular area. The Commission also sought comment on the use of spectrum sensing to identify vacant TV channels, but did not propose any specific technical requirements for devices that use spectrum sensing.
Comments were filed both in favor of and in opposition to the proposals in the Notice. Broadcasters and other TV spectrum users expressed concern about potential interference from unlicensed devices to the various services that operate in the TV bands. These services include full service TV, low power TV, TV translators, TV boosters, broadcast auxiliary services such as wireless microphones, and the commercial and private land mobile radio services. Manufacturers and users of unlicensed devices largely support the use of spectrum sensing and other measures as a means to prevent interference.
The record before the Commission does not contain sufficient information to adopt final technical rules for operation of unlicensed devices in the TV bands. For example, because the Notice did not make any specific proposals regarding spectrum sensing, there is no information in the record as to key criteria that would need to be specified to allow the use of that technique, such as the required levels for sensing, spectrum to be scanned, and durations for the sensing. Accordingly, the Office of Engineering and Technology is developing a First Report and Order and Further Notice of Proposed Rule Making that would make initial decisions and specific technical proposals necessary to adopt complete and final rules, taking into the account the comments received in response to the May 2004 Notice.

In addition, a number of parties participating in this proceeding have stressed the importance of conducting field tests to ensure that whatever standards are ultimately adopted will protect other radio services against harmful interference. We encourage interested parties to conduct tests and submit them into the record for this proceeding. In the meantime, the FCC Laboratory plans to conduct its own testing program to quantify the interference rejection capabilities of DTV receivers and to assess potential interference from unlicensed devices operating in the TV bands. The FCC Laboratory also plans to test DTV converter boxes once they become available. Details regarding FCC testing will be announced at a later time.

Taking these factors into account, the Commission staff has developed the following schedule of actions in this proceeding.

Date
Milestone

October 2006
Commission adopts a First Report and Order and Further Notice of Proposed Rule Making

March 2007
FCC Laboratory reports the results of measurements of the interference rejection capabilities of DTV receivers

July 2007
FCC Laboratory reports the results of tests evaluating potential interference from unlicensed devices to TV and other radio services

October 2007
Commission adopts a Second Report and Order specifying final technical requirements for unlicensed devices that operate in the TV bands

December 2007
FCC Laboratory begins accepting applications for certification of unlicensed devices operating in the TV bands; certification will be granted at such time as the application has been reviewed and found to comply with the rules; certification will permit manufacture and shipment of products to distribution points

February 2009
Products will be available for sale at retail

This proposed schedule provides sufficient time to develop appropriate technical standards to prevent interference to TV broadcasting and other services, as well as sufficient lead time for industry to design and produce new unlicensed products that would be available for sale to the public at the completion of the DTV transition on February 17, 2009.
___

FCC sets roadmap for using vacant TV airwaves

By Jeremy Pelofsky
Washington Post (Reuters)
Tuesday, September 12, 2006; 8:34 PM

WASHINGTON (Reuters) – The U.S. Federal Communications Commission on Tuesday set a road map for making vacant television airwaves available for other services by early 2009, when broadcasters are due to switch to digital signals. Companies such as computer chipmaker Intel Corp. (INTC.O) have been pressing the FCC to make those airwaves available to be used without a license, while broadcasters have expressed concerns about potential interference with their signals. Intel, Microsoft Corp. (MSFT.O) and others hope the unlicensed airwaves could be used for a variety of wireless services, including high-speed Internet access, particularly in rural areas where such offerings can be scarce.
“Intel believes that the TV white spaces are a prime opportunity for the deployment of valuable new wireless broadband services in rural and other underserved areas, as well as innovative wireless networking solutions in the home and office,” said Intel spokeswoman Jennifer Greeson.
The FCC said it expects to have from its laboratory test results for interference by July 2007 and would set final technical requirements for devices to use those airwaves without an FCC license by October 2007. The agency said in a notice it would accept applications for the equipment in December 2007 with the goal of having them on retail store shelves by February 2009, when broadcasters are scheduled to turn off their analog airwaves and broadcast in digital. The airwaves at issue, frequencies below 900 megahertz, are a desirable slice because the signals can easily penetrate walls, trees and other obstructions unlike the higher frequencies.
The National Association of Broadcasters praised the FCC road map. “We are pleased the FCC has taken the sensible position of ensuring that these devices will be tested rigorously and that no marketplace introduction will occur until after broadcasters complete a successful transition to digital television,” said NAB President and Chief Executive Officer David Rehr.
In 2004, the agency proposed creating two categories of users for the airwaves: one for low-power, personal, portable devices like Wi-Fi and a second group for fixed commercial operations. The FCC also proposed requiring that the devices include technology to identify unused spectrum and avoid interference. The agency said it would issue an order next month with initial decisions and technical proposals needed to complete the final rules.
Tags: radioascolto, radiofonia, radio,

printfriendly pdf button - Scusa, ti disturbo la frequenza?