Alternate Spectrum for Broadcasting: 76~88 MHz
This spectrum is the current TV channels 5 and 6. This spectrum is directly adjacent to the FM broadcast band (88~108 MHz). Channel 5 is from 76~82 MHz and Channel 6 is from 82~88 MHz.
Who uses it?
Domestic incumbent users: Channel 5: Full service TV (28), Class A TV (1), LPTV and TV translators (80). Channel 6: Full service TV (10), LPTV and TV translators (84), no Class A Channel 6 stations. One FM translator on 87.9 MHz (channel 200).
Foreign incumbent users: (In border area) Canada: Channel 5: 49 full-service DTV stations or allotments and 16 lower power digital allotments. Channel 6: 40 full-service DTV stations or allotments and 26 lower power digital allotments. Mexico has no digitial stations or allotments on Channels 5 or 6.
How do they use it?
ITU Region 2 allocation: Broadcasting on a primary basis, fixed and mobile on a secondary basis. An international footnote elevates fixed and mobile to operate on a primary basis in the United States, Mexico and the French Overseas Departments (including St. Pierre and Miquelon near Canada) but not Canada.
FCC allocations: Broadcasting (Part 73), LPTV, TV Translator/Booster (Part 74) and Low Power Auxiliary (Part 74). TV broadcaast stations may use subcarriers on a secondary basis for both broadcast and non-broadcast purposes. TV stations may use a portion of the television vertical blanking interval for the transmission of telecommunications signals on a non-interference basis. Wireless microphones are authorized in this spectrum on a non-inteference basis. Subscription television operations are permitted in this spectrum.
Federal Government allocations: (none)
Canada/Mexico allocations: Canada allocates this spectrum to broadcasting with no footnotes. Mexico allocates this spectrum to broadcasting on a primary basis and fixed and mobile on a seocndary basis. Mexican footnotes specifically permit digital television and define 76~82 as Channel 5 and 82~88 as Channel 6.
REC analysis and opinion for use as alternate spectrum
Being directly adjacent to the TV broadcast band this band would hold the most promise for alternate spectrum barring other activities taking place in the industry. While not intended for sound broadcasting, there are some low power TV stations that have exploited the audio carrier at 87.75 MHz and are operating audio only services in order to reach FM radio listeners. Some of these operations have shifted their center carrier frequency to 87.7 MHz and are running a stereo pilot tone thus questioning the legality of these so-called "franken-FM" stations. Due to the resistance by the major owners of these "franken-FM" stations, the FCC has been delaying the mandatory shutdown of analog LPTV stations which would, without any further rulemaking, result in these audio services to be shut down. 87.9 MHz is also known as "Channel 200". This channel is intended for Class D secondary non-commercial educational stations that are very distant from a Channel 6 TV station and nowhere near an international border to be able to use in the event of displacement due to changes by a full-power FM station. For many years, a small high school station in Mountain View, CA had operated on 87.9 before moving to a commercial channel. A translator in Nevada has also been permitted to migrate to 87.9 as a result of displacement. During the original LPFM proceedings, REC had recommended allowing LPFM stations on 87.5, 87.7 and 87.9 and referring to 87.5 as "America's Channel" as it would be the most available channel for LPFM due to a third-adjacent channel relationship with the nearest FM channel, 88.1 MHz.
Consumer grade radios are widely available for this spectrum but not in the United States. Japan has historically used 76~90 MHz for FM broadcasting. Japan had recently extended the FM band to 76~95 MHz in order to allow existing AM broadcast stations to obtain a high powered FM signal within their service areas. As a result of this expansion and the potential for more expansion based on the public acceptace of "multi-media broadcasting" which has authorized in Japan in the 95~108 MHz spectrum, radio are being marketed that cover the entire 76~108 MHz band. These radios, referred to as "Wide-FM" (ワイドFM) are available in all types including portable, stereo component and mobile radio. It is not believed that any of these radios with the full 76~108 coverage would include HD Radio capability. There are no known DRM+ capable consumer grade receivers for this spectrum yet however it could possibly be covered using the SDR-based prototype models. Even though DRM+ is an accepted worldwide standard for on-band digital radio, most nations are not willing to embrace on-band digital audio broadcasting (DAB) and are favoritng the world standards for off-band DAB.
Recently, the potential demand for this spectrum for television broadcasting has been increased as a result of the development of the ATSC 3.0 broadcast standard. ATSC 3.0 promises ultra high-definition television and other imporved services within a 6 MHz television channel. ATSC 3.0 is not backwards compatible with the current ATSC 1.0 standard. As a result, TV stations and consumers would need to migrate to the new standard. The FCC is allowing TV stations wishing to adopt the ATSC 3.0 standard the ability to obtain a "companion channel" with no real schedule to shut down their ATSC 1.0 channel. This use of a companion channel was also done during the original DTV transition with a hard analog shutdown date. In this case, the FCC is taking a "let the market decide" approach on whether ATSC 3.0 is accepted. Obviously since there needs to be a companion channel to viably deploy ATSC 3.0 and with the recent repacking of all TV staitons to channels 36 and below, it is very likely that TV stations will be running ATSC 3.0 in the low band VHF spectrum (54~72, 76~88, channels 2~6).
We do note though that full-service TV operations on Channel 6 still have to provide protections to non-commercial educational FM broadcast stations operating on Channels 201~220 (88.1~91.9 MHz) and these protections are one of the main reasons why many TV stations were not migrated to Channel 6 during the DTV transiton and why during the recent repack, very few TV stations were repacked on Channel 6.
Each TV channel would provide 30 200 kHz analog FM channels. REC still feels that the best way of handling AM Revitalization is to migrate Class C and D AM stations to the 76~88 spectrum as Class A FM stations on a primary basis and permitt secondary services such as LPFM to also use this spectrum. This is a much better spectrum use than for a handful of TV stations, many of which have to provide additional protections to FM broadcasting anyway. The radios to receive this spectum can be on a boat tomorrow. This would definitely be a much better use of this spectrum. It would probably require an act of Congress to make it happen though.