Broadcast auxiliary service (BAS) spectrum, the spectrum broadcasters use to bring you live news from the field, for wireless microphones in the field and in the studio, and to transmit programming from the studio to the transmitter continues to be squeezed as the FCC and others push for more sharing of the spectrum.
The FCC approved the sharing of BAS 7 GHz and 13 GHz microwave bands in December 2011 and this year we started to see non-broadcast users applying for licenses in these bands. High frequency trading depends on fast connections – milliseconds matter – and this has driven construction of new microwave networks between financial centers. Wireless carriers are looking for more spectrum for backhaul. This itself isn't a problem as broadcast use in the bands is protected, but some broadcasters may have problems with their existing links and may not even be able to remain on their current frequency if their current licenses are not accurate or complete.
Unfortunately, many older licenses do not include receive site coordinates, making protection impossible. If links are licensed for analog FM need to be changed to digital modulation, new or existing links may prevent modification for digital operation on the same frequency. Another problem I've noticed is that even when licenses have been updated, the coordinates have not always been checked. FCC rules require locations specified within +/- 1 second and height within +/- 1 meter. Licenses issued before NAD83 was adopted that are based on the NAD27 datum will not meet this criteria. If you are responsible for broadcast microwave links, verifying all the parameters on the link licenses should be high on your list of New Year's resolutions! The sharing works both ways. Broadcasters can now use Part 101 microwave spectrum for studio-transmitter links, so if they find they can't update their 7 GHz, 13 GHz or 18 GHz license due to interference, they may be able to find spectrum in the 11 GHz or 23 GHz bands.
Most TV Pickup licenses do not list receive sites. Making sure all ENG receive sites are listed on TV Pickup licenses will be important not only for the shared 7 GHz and 13 GHz bands but for protection from new wireless services on frequencies adjacent to the 2 GHz ENG band. This year the FCC allowed Dish Network to use its 2000-2020 MHz MSS spectrum for a terrestrial network. Globalstar proposed using parts of 2.5 GHz ENG channels A9 and A10 for its terrestrial network, and NTIA proposed taking the entire 2 GHz BAS band in exchange for allowing wireless broadband use in its 1755-1850 MHz spectrum.
In the past, wireless microphone users operating on “vacant” TV channels didn't have to worry too much about interference except from other wireless microphones. That changed this year with the approval of the Spectrum Bridge (12/2011) and Telecordia (03/2012) TV bands database systems. The use of TV band (“White Space”) devices was originally limited to a few test markets but the nationwide launch of the FCC's unlicensed wireless microphone registration system earlier this month allowed the FCC to authorize white space operation in New York, New Jersey, Pennsylvania, Delaware, Maryland, Washington DC, Virginia and North Carolina.
White space devices are likely to be allowed nationwide sometime in 2013, so broadcasters using wireless microphones on TV channels in the studio or for news gathering should add registering wireless microphone use with one of the approved white space database to their New Year's resolutions!
Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.
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