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The email blast from the head of my son and daughter's theater group relayed a frantic plea: "We need to raise $16,000 before the upcoming spring performances," Anya Wallach, the executive director of Random Farms Kids' Theater, in Westchester, New York, wrote in late May. If the money didn't materialize in time, she warned, there could be a serious problem with the shows: nobody would hear the actors.
Random Farms, and tens of thousands of other theater companies, schools, churches, broadcasters, and myriad other interests across the country, need to buy new wireless microphones. The majority of professional wireless audio gear in America is about to become obsolete, and illegal to operate. The story of how we got to this strange point involves politics, business, science, and, of course, money.
Story: https://www.wired.com/story/wireless-mics-radio-frequencies-fcc-saga/
(Score: 2) by kazzie on Tuesday August 14 2018, @06:35AM (4 children)
I believe the OP is concerned with interference from the new radio-based internet & cellular networks using the reauctioned bandwidth. TFA raises some concerns along this line.
(Score: 2) by RS3 on Tuesday August 14 2018, @02:59PM (3 children)
Yes, thank you, I finally understood his point and commented further down in this discussion.
I missed that point initially because, again as I commented further down, due to RF power, distances and inverse square law, etc., I can't imagine it to be a problem. Additionally, most if not all newer (even 20 years old) UHF systems allow you to program the RF frequency within a band, so you could avoid a local transmitter if receiver interference was an issue.
But also, and I know this directly, FCC isn't worried about my receiver getting interference, they're worried that my mic will interfere with "emergency services" or whatever the bandwidth has been sold to. FCC puts people in prison.
What's bugging me: as a kid I messed with "walkie-talkies". Maybe the rules have changed, or maybe I misunderstood at the time, but I remember believing that FCC allowed low-power unlicensed RF transmission provided it only carries for very short distances, like 1/4 mile or something. Of course you'd have to define the actual power level at the 1/4 mile point, etc. My point is: if my wireless mic is low power enough that you need specialized highly sensitive equipment to receive it more than say 100m away, then it should be a non-issue. People should be allowed to continue using their $5,000 systems, unless someone can prove said system is causing measurable provable interference.
That FCC sold the frequencies and told everyone "too bad for you" is outrageous. The companies who bought the frequency rights should have to replace all now unusable wireless systems.
Footnote: this whole thing happened 8 or so years ago.
(Score: 2) by All Your Lawn Are Belong To Us on Tuesday August 14 2018, @05:04PM (2 children)
I believe that the rule was actually if it was low power to a certain milliwatt ERP specification (which commonly came out to less than 1/4 mile), you accept any interference to your end, and does not cause interference to any other user you can utilize any frequency you wish... and I think separately the broadcasting rules had provisions that still limit a transmitter from making a broadcast to the public without at least a community broadcaster license (very generally - there were exceptions). And I really could be wrong but I thought those rules were still in effect. It's not "no harm, no foul" but it is close. But any interference caused if you're unlicensed/out of licensed band is still automatically your fault, and interfering with public safety comms is a criminal offense even if you were acting in good faith under that rule.
The current low power rules are here [fcc.gov], which actually specify 200 feet.
This sig for rent.
(Score: 2) by RS3 on Tuesday August 14 2018, @05:35PM (1 child)
Yes, I remember 100mW being the spec, but memory can be flawed. I intentionally omitted it because 100mW at 100KHz will carry much farther than 100mW at 32GHz, with similar antenna gain of course.
But even with a 200 foot rule, there's still some power at 200 feet, so how do you decide that it's low enough so as not to interfere with an average receiver?
My point is that in practice, the 700 MHz band wireless stuff should not be a problem and people should be allowed to continue using it until someone can measure a problem, which is pretty easy to do with a simple field strength meter. FCC worry that it will interfere with emergency services, but I'm skeptical.
Typical UHF wireless microphone systems are 50 mW https://en-us.sennheiser.com/wireless-microphone-live-monitoring-system-ew-300-iem-g3 [sennheiser.com]
(Score: 3, Informative) by All Your Lawn Are Belong To Us on Tuesday August 14 2018, @10:40PM
Very true, all.
I did just a little more digging on that page and it said that the 1991 technical notice is still actually in effect and had a link to it. The notice (which is probably what we remember) also specifies: AM 100mW to final RF and .05W ERP and FM .01uW ERP with actual spec of 250uV/M measured at 3 meters, in addition to the 200 foot maximum coverage radius and that reads more like it's cannot be picked up by any receiver at 200 feet away, period. (Also says TV is not allowed at any time).
And aside from that, it is Part 15.5 that additionally imposes the requirement that the device cause no harmful interference and that the device is disabled upon receiving a complaint from the FCC that it is causing interference, and that's aside from all the other rules.
So I guess all the old rules still apply as well.
This sig for rent.