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Back To The Future?

The wireless/RF picture for pro audio in the U.S. is finally becoming much clearer -- here's the latest

By James Stoffo September 30, 2015

PSW Top 20 presented by Renkus-Heinz

Over the past several years, entertainment production wireless system users in the U.S. have seen the energizing of digital television (DTV) and the 700 MHz band re-allocation, all the while preparing for the mass introduction of white space devices – which is now just around the corner along with the 2016 commencement of the 600 MHz incentive auction.

What does this all mean? It’s the reshaping of all entertainment production wireless operations in the U.S.

The result of the auction is going to force entertainment wireless users to operate in a greatly reduced percentage of the UHF bandwidth that had been available until the past five years or so, which is a significant loss for anyone working with wireless microphone, intercom and in-ear monitoring systems on large productions.

Further, almost all of the remaining UHF spectrum not occupied by DTV, and used by wireless microphone operators, will be shared with white space devices.

To help alleviate the issues caused by re-allocating the 600 MHz spectrum, in early August of this year the FCC announced that it is opening up some bandwidth in the higher bands for entertainment wireless use. From an FCC press statement, the new rules include:

-– Provide more opportunities for licensed use in the remaining TV bands by allowing greater use of the VHF channels and permitting co-channel operations inside DTV contours without coordination if TV signals fall below specified threshold;

-– Expand eligibility for licensed use of the 4-megahertz portion of the 600 MHz duplex gap to include all licensed users in the TV bands (broadcasters, cable programming networks, movie studios, and operators at major sporting/concerts/theater venues); and

-– Provide new opportunities for these licensed wireless microphones to operate on a secondary basis in three additional spectrum bands, consistent with the Commission’s spectrum management goals – (1) access to significantly more spectrum in the 900 MHz band; (2) access to a portion of the 1435-1525 MHz band at specified times and places, subject to coordination requirements that protect critical aeronautical mobile telemetry; and (3) access to portions of the 6875-7125 MHz band.

However, it’s important to note that these much higher frequency bands may not be conducive to reliable wireless system use beyond relatively short distances. The higher you go in the spectrum, the more difficult it is to make wireless work the way that we in the production community use it.

Hello VHF?
When wireless systems were introduced more than 50 years ago, they operated only in the VHF bands (30 MHz to 300 MHz). This is also where all TV operations were located, and just about all civilian RF equipment. As technology progressed, there was a great deal of movement to the UHF band, including the majority of wireless systems, as it was far less congested at the time and allowed for smaller antenna sizes and other benefits. Gradually UHF wireless systems became the standard and VHF systems all but disappeared.

However, with the upcoming re-allocation of the 600 MHz band, VHF for wireless microphone systems is getting renewed interest. Incorporating new manufacturing techniques and sophisticated DSP technology into VHF products eliminates many of the RF and audio quality issues from a generation ago, all while keeping the size down.

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