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25th Anniversary of FCC Decision Enabling Wi-Fi and Bluetooth

25th Anniversary of FCC Decision Enabling Wi-Fi and Bluetooth
A series of posts describing how this all came about. (Click on picture above)

Friday, July 18, 2008








New Wireless Microphone Complaint and Petition


This week the Public Interest Spectrum Coalition filed with FCC a complaint about the massive marketing of wireless microphones to users who could not legally use them - creating de facto allocations and service rules without the benefit of policy deliberations and consideration of the long term implications.

This petition results, in part, from some work I did for the New America Foundation, a PISC member. The concepts are also related to my March 10, 2008 post entitled "Wireless Mics are a Legitimate Use of Spectrum:They Deserve More from FCC than Benign Neglect that Allows Most Users Only Criminal Spectrum Squatting".

The basic points of the FCC filing are:
• Begin an investigation against Shure, Inc., and the other manufacturers listed in the informal complaint, for willfully and knowingly marketing and selling wireless microphones to unauthorized users for ineligible purposes in violation of Part 74, Subpart H, and for engagingin deceptive advertising practices designed to persuade ineligible users such as houses of worship, theaters, corporate event venues, and members of the general public that they could legally purchase and operate wireless microphones operating on vacant broadcast UHF Channels without a license and for purposes prohibited by the Commission;

•Grant a general amnesty to all unauthorized users of wireless microphones deceived by the
illegal and deceptive marketing of manufacturers, permit use of the illegal equipment on a
going forward basis until the Commission authorizes the proposed GWMS, and require those
manufacturers that engaged in illegal marketing to migrate the unauthorized users of Part 74,
Subpart H equipment to the new GWMS by replacing equipment authorized for Part 74,
Subpart H with equipment authorized for use in the GWMS;

•Immediately reclassify all licensed wireless microphone systems operating pursuant to Part 74, Subpart H as secondary to all advanced wireless service (AWS) and public safety systems authorized to operate on television Channels 52-69 following the shut off of analog television transmission;

• Order that manufacture, sale, and advertisement for sale of wireless microphone systems operating on channels 52-69 cease immediately; and

• Create a new “General Wireless Microphone Service” (GWMS) licensed by rule pursuant to Section 307(e) to operate on vacant broadcast UHF channels below Channel 52 on a secondary basis to broadcast licensees and individually licensed wireless microphone systems, and authorized on a primary basis to operate on the 2020-25 Band currently authorized for broadcast ancillary service (BAS) and under consideration for reallocation in Docket Nos. WT 07-195, WT 04-356 (“
AWS-2/AWS-3 Proceeding”).
It has always amazed me that in a law and order-oriented Republican administration this lawless behavior has been tolerated even when it involves the illegal and dangerous use of public safety spectrum. (In the case of immigration reforms, don't most Republicans think that those who have violated the law should not be given amnesty and should go to the "back of the line" with respect to benefits? In this case, the "liberal" members of PISC are at least consistent with the liberal view of immigration issues. It will be interesting to see how Republicans view the issue.)

Indeed, it is amazing that this complaint comes from PISC, not CTIA or its cellular behemoth members that have recently spent billions for the spectrum that Shure encourages their customers to use and not from APCO that hounds the FCC for more spectrum but has ignored protecting the spectrum from such intruders. (While there may not be a documented case of wireless mic interference to public safety in the FCC records, we all know that public safety systems frequently have marginal repeater coverage inside buildings. (Remember what happened at the World Trade Center when the firemen couldn't get receive the order to evacuate?) When the downlink signal is marginal, small cochannel signals can easily cause interference. So CTIA and APCO members might want to ask their trade associations why they have been ignoring this spectrum squatting for so long.

Discussion in Harold Feld's blog
including exchange with Henry Cohen, an engineer active in Broadway use of wireless mics.

AP story

Chicago Tribune story. Includes this discussion of Shure's views,

Shure spokesman Mark Brunner said the company is aware of the potential interference problem from the digital transition and hasn't sold products for that spectrum since late 2007. [Wow - they stopped in the past year. Maybe they finally read something in USA Today about the 700 MHz auction! Maybe news travels slowly "outside the Beltway? What have they told customers that bought this equipment? The world wonders. - MM]

As for the broader issue of how so many unauthorized users were allowed to purchase wireless microphones, Brunner said technological advances and market practices of the last several years simply overtook the outdated FCC rules.

"Those rules were written several decades ago, when wireless microphones were a bit more crude than they are today. … Over time, no interference complaint has really resulted," Brunner said. "The technology got better and more industries decided they were interested in using these products. … The rules were never really updated to reflect that."
Did it ever occur to Shure to ask FCC to change its rules rather than selling hardware to users who use of it would be in violation of criminal law and might endanger public safety where the FCC's tolerance of interference risk is rightfully near zero?

3 comments:

Henry Cohen said...

"(While there may not be a documented case of wireless mic interference to public safety in the FCC records, we all know that public safety systems frequently have marginal repeater coverage inside buildings. (Remember what happened at the World Trade Center when the firemen couldn't get receive the order to evacuate?) When the downlink signal is marginal, small cochannel signals can easily cause interference."

First of all, the WTC had communications issues long before, and completely separate from the issue of co-located channel use (in fact there was no co-channel use in the WTC on the VHF fireground frequencies). Additionally, when the first tower collapsed, so went the city-wide repeaters. Apples and oranges.

But more importantly, it's vital to this entire argument to understand that production wireless equipment would *never* be tuned to, or within 100kHz of, active licensed [PS] frequencies (I'm referring to T-band as it's the only present day spectrum "shared" between Part 74 and Part 90) for the simple reason that the Part 74 devices would suffer unacceptable interference (and the client would then not pay us). Our spectral inefficiency is the saving grace here; most Part 74 devices need at least 200kHz channel bandwidth. At this point a narrowband portable radio, especially one designed for the PS market, has more than enough front end selectivity to filter out a nearby low power signal 100kHz, even 50kHz away. (Remember that the FCC is requiring that two-way radios use no more than 12kHz channels by 2010 - and most now do - and is pushing for 6kHz channels by 2014.

I readily concede the legal arguments made in the informal complaint and even agree that Part 74 devices should not be permitted in the 698-806MHz spectrum for policy reasons. But the engineering arguments made by the PISC, NAF, Whitespace Coalition, et al are completely devoid of any understanding, valid engineering tests or studies concerning how Part 74 devices are deployed by professionals in a production environment.

MJM said...

The previous comment stated,

"But more importantly, it's vital to this entire argument to understand that production wireless equipment would *never* be tuned to, or within 100kHz of, active licensed [PS] frequencies (I'm referring to T-band as it's the only present day spectrum "shared" between Part 74 and Part 90) for the simple reason that the Part 74 devices would suffer unacceptable interference (and the client would then not pay us)."

Public safety systems are generally half duplex: mobile transmit on one frequency (uplink) and repeaters transmit on another frequency (downlink). I was referring to downlink public safety signals/frequencies that are sometimes weak inside buildings due to limitations in public safety coverage. If the downlink signal is weak inside a building, wireless mics can be used on the downlink frequency without experiencing interference itself. But a public safety user entering the inside area near the wireless mic may well be jammed by it.

Note that wireless mic manufacturers in their advice to their customers have not in the past told them to avoid public safety spectrum. Noneligible wireless mic users, the majority of present users, can not use the established SBE Part 74 coordination process.

The system is ripe for major reform that reflects the reality of the situation. Rewarding manufacturers that have profited by selling equipment to noneligible users without even petitioning FCC for a change should not be a high priority in setting up the new policy.

Henry Cohen said...

Public safety systems are generally half duplex: mobile transmit on one frequency (uplink) and repeaters transmit on another frequency (downlink). I was referring to downlink public safety signals/frequencies that are sometimes weak inside buildings due to limitations in public safety coverage."

I too was referring to the downlink: That's usually the stronger signal that concerns Part 74 device users.


"If the downlink signal is weak inside a building, wireless mics can be used on the downlink frequency without experiencing interference itself. But a public safety user entering the inside area near the wireless mic may well be jammed by it."

I understand exactly what your hypothesizing and even agree that such a scenario is possible. My point however is that after 20+ years of Part 74 devices operating in the 470-512MHz spectrum shared with T-band in the 13 MEAs, there has, as far as I can ascertain from the FCC search engine, not a single PS complaint or anecdote of interference caused by a Part 74 device.


"Note that wireless mic manufacturers in their advice to their customers have not in the past told them to avoid public safety spectrum."

And that is irresponsible from a public policy perspective and just plain stupid from a customer service perspective.


"Noneligible wireless mic users, the majority of present users, can not use the established SBE Part 74 coordination process."

Yes and no. The SBE coordinators are generally quite willing to help out a production for minimal compensation. The more professional and seasoned Part 74 users do their own advance work by searching the Media and ULS databases to look for licensed frequencies in the area they'll be operating, and then scan the spectrum upon arrival for additional frequencies to avoid.


"The system is ripe for major reform that reflects the reality of the situation. Rewarding manufacturers that have profited by selling equipment to noneligible users without even petitioning FCC for a change should not be a high priority in setting up the new policy."

Agreed.