Wireless Mic Follow Up: Turns Out Public Safety Did Get There First

One may logically ask, if I am right about the wireless microphones being such a big problem for public safety, why haven’t the public safety folks complained to the FCC about this?

Answer: turns out they have. But, the public safety folks being quiet and unassuming, failed to make themselves heard.

Allow me to change that. The National Public Safety Telecommunications Council, a federation of public safety associations, sent a letter to Chairman Martin asking that the FCC address the problem of wireless microphones back on June 30, 2008. i.e., about two weeks before I filed. While I wish I could claim that it was the NPSTC letter that inspired me, I had no idea it was out there until today. My conversations with the public safety guys were all informal and off the record. Still, as always when folks remind me I’m not an engineer (or an economist, or technologist, or any of the other topics on which I chose to share my humble layperson’s opinion), I am rather pleased to find a bunch of actual engineers that agree with me.

Mind you, the NPSTC letter asks the FCC to go a heck of a lot further than I have. NPSTC wants wireless microphones kicked out of the entire 700 MHz band. I, OTOH, think lots of folks can productively use the broadcast white spaces. Still, I do feel compelled to point out that wireless microphones do not have nearly the level of intelligence/sophistication being discussed for interference avoidance for the white spaces devices at issue in 04-186. Perhaps we should require wireless microphones to rely on sensing as well, or require that they consult an online database for possible new users in the band, or require them to acknowledge some sort of “permissive beacon.” Perhaps public safety entities like NPSTC should administer the database or beacon, and we should require wireless microphone users to pay for these services.

I mean, after all, we wouldn’t want to let these devices run around loose, would we? Think of the terrible interference that might cause. Unless these devices can meet the same rigorous standards that Shure and others seek to impose on unlicensed devices in 04-186, I don’t see how we can ask NPSTC to abide by circumstances that they feel place our public safety at risk.

Stay tuned . . . .

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One Comment

  1. Henry Cohen says:

    “One may logically ask, if I am right about the wireless microphones being such a big problem for public safety, why haven’t the public safety folks complained to the FCC about this?

    Answer: turns out they have. But, the public safety folks being quiet and unassuming, failed to make themselves heard.

    Allow me to change that. The National Public Safety Telecommunications Council, a federation of public safety associations, sent a letter to Chairman Martin asking that the FCC address the problem of wireless microphones back on June 30, 2008.”

    As I’ve stated before, I fully agree and support any policy that prohibits *any* secondary services and operations in any PS band, but I find it increasingly interesting, if not outrightly ridiculous, that after 20+ years of shared Part 74 operations in T-Band (authorized in 1978 as best as I can ascertain) where PS operates in the 13 MEAs, there has not been one interference complaint, or request to prohibit Part 74 devices, by the PS community, given everyone’s great concern over possible 700MHz interference. I’d really look forward to a [cogent] explanation.
    “Still, as always when folks remind me I’m not an engineer (or an economist, or technologist, or any of the other topics on which I chose to share my humble layperson’s opinion), I am rather pleased to find a bunch of actual engineers that agree with me.”

    Again, I ask if any of the engineers you’ve spoken with have any practical experience coordinating, deploying and operating Part 74 devices in a production environment? Simply because I’m an RF engineer, doesn’t qualify me to theorize on EW countermeasures system operations, for example, for the purposes of policy making. Or, let me use an analogy closer to home; an attorney fluent in telcom and related technology policy is not necessarily qualified to mount a competent defense for a client accused of robbery.
    “Still, I do feel compelled to point out that wireless microphones do not have nearly the level of intelligence/sophistication being discussed for interference avoidance for the white spaces devices at issue in 04-186.”

    Ahhh, but wireless microphones and other Part 74 devices *do* have an intelligence and database referral (at least at the professional level): It’s called the operator. Precisely because Part 74 devices are so susceptible to higher power and broadband digital interference, professionals make significant efforts to consult the FCC database for co-located operations prior to arrival at the event site and then affirmatively scan for clear frequencies once at the event location.
    “Perhaps we should require wireless microphones to rely on sensing as well, or require that they consult an online database for possible new users in the band, or require them to acknowledge some sort of “permissive beacon.””

    Your ‘beacon’ already exists: It’s the high power or digital signal already occupying the frequency, whether it be the fixed control point (base station) or the portable device (‘walkie-talkie’ and data terminals).
    “I mean, after all, we wouldn’t want to let these devices run around loose, would we?’

    But we already do (T-band), for nearly 30 years, and with no [reported] interference problems.
    ”Think of the terrible interference that might cause.“
    Can’t think of, or find, a single instance.
    ”Unless these devices can meet the same rigorous standards that Shure and others seek to impose on unlicensed devices in 04-186,“

    Are you equating a narrowband (100kHz) 50mW device to a broadband (5.8MHz) 100mW burst device? Wow. But then neither Part 74 devices or license-free (‘unlicensed’ could be a license required device being used with out a license – sort of like wireless microphones, or a driver of an automobile) devices should be permitted to operate in PS spectrum.
    ”I don’t see how we can ask NPSTC to abide by circumstances that they feel place our public safety at risk.”

    Maybe NPSTC doesn’t remember T-band? And maybe that’s because there’s been no problems?

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