Sep

6

Rebutting TV and Microphone Industry Claims on Interference if Vacant TV Channels are Opened for Broadband Devices.

sascha's picture

I've been mired in a pitched battle between the public interest (to allow the general public to use unlicensed devices on unused TV frequencies) and the National Association of Broadcasters and various massive corporations (who have launched a FUD campaign of epic proportions here in the nation's capital). Just today I learned that NAB and its allies have taken out full-page adds in various press going out to congressional offices claiming that these technologies will destroy TV as we know it. If this claim sounds familiar, it's because it was the same claim used to fight low power FM radio -- a claim that has since been proven to have been a lie.

Here's the latest:

    Today the New America Foundation, Media Access Project and leading spectrum engineers filed Reply Comments at the FCC (Docket 04-186) with further evidence demonstrating the feasibility of "smart radio" technology that allows low-power broadband devices to detect and utilize vacant TV channels without causing harmful interference to TV viewers. The FCC is currently completing a rulemaking that could open unused TV band "white space" for unlicensed access.

    Broadcasters and wireless microphone makers, which currently utilize less than half of the frequencies reserved exclusively for their industries, have tried to distort a recent FCC report that tested initial prototype devices submitted by Philips Electronics and Microsoft. Today's filing adds both new measurements and a critique of the broadcaster/microphone lobby claims.

    "There is no longer any doubt about the feasibility of mobile, low-power devices to detect-and-avoid channels occupied by licensed TV channels or wireless microphone systems," said Michael Calabrese, director of New America's Wireless Future Program. "The remaining challenge for the FCC is to define explicit operating rules to govern device certification, so that America's high-tech industries can embark on the R&D necessary to bring compliant consumer devices to market."

    The Reply Comments include the following major points:

    * Measurements at the University of Kansas spectrum labs shows that both DTV channels and low-power broadband devices can operate in three consecutive channels with no harmful interference.

    * Since the vast majority of wireless microphones are themselves unlicensed devices - and have been using vacant TV channels illegally, yet without complaints of interference - the FCC should offer them no further protection than NAF et al.'s proposal to allow sports, theater, concert and other venues to bar, or require patrons to turn off, mobile broadband devices during their events.

    * Although the FCC labs found that White Space devices can operate as close as 2 meters from a DTV without causing interference, the Commission should follow the approach it has used for personal computers and other unlicensed emissions - and assume that at distances less than 10-to-20 meters, consumers can take self-help to remedy interference from a mobile device.

    * The broadcast lobby (MSTV/NAB) submitted interference measurements, concerning the ability of devices to detect weak TV signals, that are clearly unreliable and erroneous.

    * The Commission should reject the overly conservative detection threshold for weak TV signals proposed by the high-technology White Spaces Coalition (Microsoft, Philips, Dell, Google, et al.) since prohibiting the access to channels with signals from distant TV markets would protect few viewers, but deprive all Americans of broadband services.

    Today's filing builds on NAF et al.'s initial Comments, filed August 15, on the FCC/OET Report.

    New America's Wireless Future Program develops and advocates policy proposals aimed at achieving universal and affordable wireless broadband access, expanding public access to the airwaves and updating our nation's communications infrastructure in the digital era. For more information, visit www.spectrumpolicy.org.

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  1. David (not verified) on Fri, 2008-10-17 17:40

    Interesting article. Your facts err in a few significant points:

    * There is a difference between "unlicensed" and "illegal." Wireless microphones and other products are not illegal, though they are unlicensed. They are in fact completely legal.

    * White spaces are not currently "unused" as you claim. They're actually quite heavily used with the aforementioned non-licensed, completely legal wireless microphones. In some areas, they're used so heavily that it's hard to find RF space to add new frequencies.

    Re-allocating white-space spectrum would indeed effectively and beneficially create a new industry (the exact nature of which is still to be determined) but it would adversely impact several other industries including:
    * all public performance theaters;
    * nearly all musical performance venues including professional, collegiate, and high school levels;
    * all public news-gathering organizations, both in-studio and in-the-field;
    * nearly all public religious meetings;
    * all professional sports events, most college level sports events, and not a few high school sports events;

    The idea of requesting that every attendee at a pro football game, a concert performance, or live news broadcast scene turn off their devices and then counting on their compliance is laughably ignorant: it is unenforcable, and the consequences of their noncompliance could be show-stopping.

    Rather than simply re-assigning all white-space bandwidth to new technology, it would be prudent to offer a shared approach, such as has been proposed by some of the microphone manufacturers: allocate a few channels to wireless mic use; allocate the rest to the new white-spaces devices.

  2. sascha on Tue, 2008-10-21 11:33

    Part 74 rules are pretty clear about who can legally use wireless microphones (and that one needs to license all wireless microphones). Most wireless microphones are being used illegally -- they are illegal in the same way that a pirate radio station is using an illegal transmitter.

    I would also recommend taking a look at the NSF-funded research that actually looked at spectrum use throughout a number of bands. You can get a feel for these research results (and download the full reports) at www.sharedspectrum.com/measurements. As you'll see from the graphs on that page, spectrum analysis documents that even in the most heavily utilized bands, occupancy barely clears 25%.

    I'd certainly be interested in reading through any documentation of the claims you're making. In the interim, the research and analysis that's been collected thus far is fairly clear on the points made in the paper and do not support many of the claims you're making.


  3. Henry Cohen (not verified) on Tue, 2008-10-21 16:16

    ". . . spectrum analysis documents that even in the most heavily utilized bands, occupancy barely clears 25%."

    I don't know what you mean by "most heavily utilized bands", but I take it to mean the post transition UHF-TV broadcast spectrum; 470-608MHz, 614-698MHz (channel 14-36, 38-51), or 37 UHF channels.

     

    Los Angeles post 17 Feb '09 channels in use by full power DTV, translators, boosters. LPTV and T-band:

    T-Band: 14, 16,

    Full power DTV: 18, 20, 23, 24, 32, 34, 26, 28, 29, 31, 34, 35, 36, 38, 39, 41, 42, 43, 44, 47, 48, 49, 51

    Boosters/translators/LPTV : 25, 27, 33, 45

    LA Summary: 29 out of 37 channels used = 78%; 8 unused channels = 22%

     

    New York City area post 17 Feb '09 channels in use by full power DTV, translators, boosters. LPTV and T-band:

    T-Band: 14, 15, 16, 19

    Full power DTV: 17, 18, 21, 23, 24, 26, 27, 28, 29, 30, 31, 33, 36, 38, 40, 41, 42, 44, 47, 48, 49, 51

    Boosters/translators/LPTV : 32, 34, 35, 39

    NYC area Summary: 30 out of 37 channels used = 81%; 7 unused channels = 19%

     

  4. sascha on Tue, 2008-10-21 18:37

    Henry -- take a look at the NSF research reports at the link I listed above. They provide indepth analysis and discussion of the research methodology used when conducting their spectrum measurements. The results they report are based on on-the-ground measurements of actual spectrum use.


  5. Henry Cohen (not verified) on Wed, 2008-10-22 18:42

    This is where you policy guys confuse me: I thought this thread was about WSDs and wireless microphones, which means the only frequency range relevant is 512-608MHz, 614-698MHz (UHF-TV channels 21-36 and 38-51).

    So why is a report that covers 30MHz - 3GHz, with measurments taken from roof tops and "measurements taken within the Public Safety bands are of special interest, as these data were collected with higher resolution when compared to the other bands studied" so meaningful to this topic? If the intention is to operate WSD's from only rooftops, we can conclude any objections from Part 74 device users and I'll buy the first round in the poshest beltway establishment of your choosing (with a rooftop terrace of course).

    I'm still reading the reports, but so far SSC's testing methodology is completely absent of any enironmental and logistical considerations of how and where wireless mics/coms/IEMs/IFBs are used. These reports are also four years old and I can tell you for a fact the NYC RF spectrum signature has changed considerably 400MHz - 2.7GHz.

     That said, I'm finding their reports quite fascinating.

  6. sascha on Thu, 2008-10-23 15:22

    I agree, there is precious little in the way of objective empirical, methodologically rigorous data on actual spectrum use. I'd love to have more up-to-date information on actual spectrum use -- the only in-depth analyses I've seen in recent years on TV frequency use are from Microsoft. I believe they were put into the 04-186 docket as an ex parte.


  7. Henry Cohen (not verified) on Thu, 2008-10-23 16:36

    Unfortunately it's not really possible to collect objective empirical, methodologically rigorous data on actual spectrum use in any defined geographical area that is valid once the spectrum analyzer is turned off and you go home, especially today when on a continuous basis new RF devices and systems are sold and deployed (license free Part 15 products are a particular problem in this regard), and all types of mobile and temporary operations move about, especially in major metropolitan areas. The SSC reports are nothing more than snapshots in time.

    On many occasions, I've done multi-day events in NYC outside and the RF spectrum we used (450-806MHz, 902-928MHz, 942-961MHz, 2.4GHz and 5.1-5.8GHz) changed significantly from the morning to the afternoon, from daytime business hours to night time, from weekday to weekend. And I'm not even referring to intermittent transmitters such as two-way radios and PTTx intercoms.

    This is an overall RF engineering and logistics problem that extends far beyond our mere WSD versus Part 74 device row.

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