THE CGC COMMUNICATOR
Friday, September 5, 2008
Robert F. Gonsett, W6VR, Editor <cgc (at) cgc333.connectnet.com>
Copyright 2008, Communications General® Corporation (CGC)
A POTENTIAL ONSLAUGHT OF WIRELESS MICROPHONES IN THE 944-952 MHZ AURAL STL BAND
Recently, Richard Rudman, chairman of the Southern California Frequency Coordinating Committee, Inc. ("SCFCC"), received a sales brochure from Location Sound Corporation. Location Sound sells radio equipment to television and motion picture production companies, and one of Location's front page articles touted the virtues of using 944-952 MHz for wireless microphone applications. Richard spread the word.
That article set off alarm bells with a number of engineers in Los Angeles -- and will undoubtedly soon concern radio broadcast stations across the United States as churches and others seek new spectrum outside of the 700 MHz band. As most of you know, 944-952 MHz is the licensed studio-to-transmitter ("STL") band relied upon by many radio broadcasters and the band is extremely sensitive to interference hits.
Because of the immediate need to protect the 944-952 MHz spectrum and because Location Sound had not amended their advertising article after being contacted, a formal complaint was filed with the FCC. The complaint contains the thoughts and suggestions of a number of southern California broadcast engineers and is reproduced in its entirety below (less the attached pdf data file).
Undoubtedly SBE, NAB, NPR and others will take a very close look at the issues involved, and hopefully some accommodation will ultimately be reached. Watch the trade press as this story develops.
LOCATION SOUND NEWSLETTER ARCHIVED
If the Location Sound newsletter mentioned below disappears from the Web, use this address for an archived copy:
TEXT OF THE WIRELESS MICROPHONE COMPLAINT
Filed with the Los Angeles FCC office September 3, 2008:
This formal complaint concerns the marketing practices of Location Sound Corp. (LSC) of North Hollywood, CA. Particular reference is made to their recent newsletter posted at <http://www.locationsound.com/pdf/Newsletter.pdf>. On page 1 in the right hand column of that newsletter, there is a story entitled, "Important RF Spectrum News" that encourages non- broadcasters to use the 944-952 MHz spectrum for wireless microphone applications. The first paragraph claims in part that, "This little known area of UHF spectrum is, for the most part, wide-open and available for production use." In fact, it is neither wide-open nor available to non-broadcasters such as TV and film producers and operators of theme park shows.
944-952 MHz is intensively used for licensed aural Studio- to-Transmitter (STL) broadcast links across the United States. With current wireless microphone users moving out of the 700 MHz band, 944-952 MHz may appear to be virgin territory for frequency relocations, but this is not the case. Operations in the 944- 952 MHz band must be licensed under Part 74 and the only parties eligible to use this spectrum are broadcasters. See FCC Rule 74.832(d).
The Commission is urged to:
(a) promptly contact LSC to request, at a minimum, that LSC retract or suitably amend its "Important RF Spectrum News" story so as to emphasize that all 944-952 MHz users must be licensed and that only broadcasters are eligible to use this spectrum,
(b) request that LSC notify all parties who purchased 944- 952 MHz transmitters from LSC of the true and correct licensing and eligibility requirements for using this spectrum,
(c) investigate the marketing practices of others, such as Shure and Sennheiser mentioned in the LSC newsletter, to determine if they, too, are failing to properly alert prospective equipment purchasers of the strict limitations involved in using the 944- 952 MHz band,
(d) issue a Public Notice reminding manufacturers, distributors and users of wireless products that low power auxiliary operations by cable television companies and motion picture and television program producers are authorized only in the bands allocated for TV broadcasting as spelled out in Rule 74.832(d) -- and not in the 944-952 MHz band, and
(e) determine what authorization, if any, Location Sound relied upon when "LSC recently installed 944 band (equipment) at the "Blues Brothers Review Show" at Universal Studio Tour" (Location Sound newsletter, page 1, paragraph 4) since this show was stated to be "right in the middle" of a theme park and was, therefore, apparently ineligible to use the 944-952 MHz spectrum.
Prompt FCC intervention is respectfully requested to prevent debilitating interference from wireless microphones (or IFB or other transmitters) to existing aural STL systems. Thank you for considering the issues presented in this complaint.
Postscript: One Los Angeles consulting radio engineer has written as follows. "Right now I have two clients that are being hit with random signals that drop out their on-air digital STLs - both of them are on Mt. Wilson. The problem may not show up for a week or so then it's an all day or all evening problem. I've discovered it doesn't take much to cause major bit error faults to very robust signals. At a minimum, Location Sound Corp. needs to print the fact that this is a very busy band and a service monitor or the best spectrum analyzer and antenna on the ground is not going to discover many of the channels that are in use and being received at highly elevated sites.
"Knowing the production world the way I do, it wouldn't be too long before IFB transmitters appear on the band, some using MiniCircuits power amplifiers. This is a common practice in other bands. I suspect that even with being warned about the STL useage, many operators, with confidence, will use wireless mic systems that have the supposed capability to search for "open" frequencies and light up on them. The best thing would be for the various manufacturers to not make wireless equipment that will operate in this band."
The pdf file attached hereto was provided by a Los Angeles broadcaster and contains 40 pages of data showing the intense use of the 944-952 MHz band by existing, licensed, aural STL systems within a 100-mile radius of Mt. Wilson.
The CGC Communicator is published for broadcast engineering professionals in so. California by Communications General® Corporation (CGC), consulting radio engineers, Fallbrook, CA.
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