Concerned that the government may reallocate some or all of their spectrum to wireless broadband, TV broadcasters — commercial and noncommercial — have begun mounting a defense of their airwaves.

In comments filed with the FCC as part of its inquiry into improving broadband access to the Internet, the broadcasters said their digital over-the-air signals are an integral part of the service they provide today and the basis for new digital services tomorrow like mobile TV.

They also said that over the years they have vacated a third of the spectrum originally allocated to broadcasting so that it could be used for other purposes.

The National Association of Broadcasters and the Association for Maximum Service Television (MSTV) filed joint comments on behalf of commercial broadcasters.

They said that the broadcaster's transition to digital, completed just this June, produced additional efficiencies in the use of the broadcast spectrum.

"The multi-billion investments by broadcast television stations, equipment manufacturers, the government and consumers have enabled the intensive use of each television station's 6 MHz channel to deliver a variety of high-definition and multicast programming, mobile DTV and other ancillary and supplemental services — all while freeing up more than 100 MHz of spectrum for wireless broadband and other new commercial and public safety uses."

NAB and MSTV challenged the assertion of FCC Chairman Julius Genachowski and others that there is a severe shortage of spectrum available for wireless broadband.

"A significant amount of exclusively licensed spectrum has been repurposed in anticipation of the spectrum needs of the commercial wireless industry," they said. "Owing to a host of variables, these bands have only begun to be put to use."

The commercial broadcasters also said the wireless broadband providers could do a better job of using the spectrum they now have more efficiently. They "can add capacity for broadband by improving the technology, architecture and system design currently deployed over their legacy spectrum bands," the groups said.

Instead of increasing wireless broadband spectrum by 300 percent as some have suggested, the broadcasters said, the goal should be to improve the efficiency of spectrum used by wireless broadband by 300 percent.

The value of broadcasting's use of spectrum cannot be evaluated in strictly financial terms, the broadcasters added. "Over-the-air broadcasting reaches virtually every household in America, and is engineered to serve core public interest goals such as local journalism, universal service, diversity, competition, local economic activity, availability of educational programming, and timely provision of emergency information.

"If these objectives were not a factor, the television broadcast service would have different technical and economic characteristics; among other points, it likely would not be free and available to all Americans, especially in more sparsely populated areas."

According to the commercial broadcasters, TV uses just 60 percent of the spectrum that it used in the 1970s. "Yet, [it] has managed to provide a four-fold improvement in the audio and video quality of its service.

"With the conclusion of the DTV transition, broadcast television is the first wireless service ever to substantially reduce its spectrum use while providing additional services."

First, they said, broadcasters vacated ch. 1, then channels 70 through 83 and most recently channels 52-69. In addition, broadcasters are giving up 35 MHz of spectrum in the 2 GHz band that they had been using for ENG microwave links.

"These and other steps have accommodated commercial wireless 4G networks, mobile satellite services, land mobile communications, broadband public safety networks and low-power television services, among others," they said.

The broadcasters also said that consumers have invested tens of billions of dollars in digital receiving equipment. "If, hypothetically, there were any further reallocation of the broadcast television service, consumers' investment in their receiving equipment would be stranded.

"Perhaps, more importantly, consumers would lose access to the free local programming, news, weather, sports, emergency services, mobile, DTV and other programming and services previously delivered over the reallocated spectrum."

The noncommercial sector of TV broadcasting — represented by the Association of Public Television Stations, the Corporation for Public Broadcasting and the Public Broadcasting Service — filed joint comments that made some of the same points as the commercial broadcasters.

"With the recent transition to digital-only broadcasting, the nation's 364 local public television stations are leveraging the new technologies to expand their educational and informational offerings and deliver a number of enhanced services to the public that could only be dreamed of in the analog world," they said.

The stations offer a mix of HD and SD streams, they stated. "In addition, stations are maximizing their digital capabilities to serve the public interest both by enhancing their traditional educational offerings through datacasting and by offering news services in public safety and public health with an eye toward our nation's priorities in a post-9/11 world."