Wireless 700 MHz microphone interference?

C

cpf

Well-Known Member
(Hope this isn't breaking any rules)

A unspecified group is doing a large event in my place, and they have a stock of 26.5^2 MHz-range wireless microphones they were hoping to use. Long story short, they don't work that well, cutting in and out, hissing/static, and this is with nearly all of them (they're fixed-frequency, forget the exact model, probably 5-7 years old). Of course I'm trying to convince them to upgrade away from the 1400/2MHz spectrum, but "it's illegal" hasn't swayed them. Is it possible these performance problems are related to their less-than-legal status, too? I'm hoping to find some way to stop them from just buying new, but equally illegal transmitter packs that might not even fix the performance problem.
 
That spectrum, which was largely vacant in the "glory days" of a decade ago, is beginning to become increasingly populated with new services. There are public safety allocations, plus the telecoms' new systems. It's only going to get worse.

I believe the new systems going in are distributed (for good two-way coverage) and likely digital (so there aren't the old "holes" between aural and visual carriers of NTSC).

An off-the-top-of-my-head analogy: Let's say you ride a horse to work in an adjoining city. You've been riding the same horse for years, and possibly another one before it, on the same path, and it works fine. Then an interstate highway is built along, or intersecting, your path. The horse gets run over by a truck (we'll say you're okay; it's an analogy). You could buy another horse and drive it on the same path, but it'll just get run over by another Mack truck. The problem isn't the horse, or the highway, but the path you're riding. You need to choose a better location, where your horse and the highway traffic don't run into each other. Similarly, even if only to avoid interference, the necessary solution is moving to a more forgiving (and also, as you note, legal) bandsplit.
 
Seeing that it is there equipment which is Illegal and Bad, or Bad because it's illegal, or just bad because it's old, or Old and there fore bad in comparison to new; here's my two cents.

Give them the facts of life, which it seems like you have. I personally don't think I would stress over getting there bad system to work. If they were still in a legal bandwidth and just not very good equipment i'd stick it out and make the best of it that I could. I don't think you would be out of line telling them straight up that you will not troubleshoot their now illegal bandwidth equipment. If they have their own guy or someone that will fight with it great, but i wouldn't bring that stress and "co-illicit" activities on myself your yourself.

I know when equipment that been used for years suddenly doesn't work, and can't be used because the gov't says so sucks. But... that's life.
 
Since they are not your systems are they for some reason looking to you to somehow resolve the problems caused by their wireless systems?

Even if they were operating on legal frequencies I believe that unlicensed devices having to accept any interference from licensed users applies in Canada as it does in the US. And as Wayne noted, that is probably exactly what is happening with the proliferation of all the new "4G" and similar networks.

This could be a touchy topic for venues. It is one thing to have a Contract that says the lessee/rentee is responsible for all licensing and system operation but I see it potentially being a bit like copyright where you may not be the ones directly causing the violation but you are benefiting from it, it's on your property, etc. so you may assume significant risk. That risk and responsibility may increase if you know that the equipment is being operated illegally, which in the case of 350*2 MHz wireless microphone systems you know it is. How have others dealt with this situation or the potential of it?
 
It's very likely that these performance issues are being caused by new wireless services. "4G" (not really, but that's an argument for another day) LTE operates at 700 MHz in North America, and with the Verizon rollout in the US the spectrum gotten pretty full already. BTW, Verizon can and will go after you if you cause damage to their network by running 700 MHz wireless microphones...
 
The simple solution is to add a line to the rental contract which says, "Wireless equipment which uses illegal parts of the spectrum will not be used in our facility".

Seems like an important issue for all facility management to discuss. It seems likely that if the FCC came hunting someone down for using those frequencies they would hold the facility management equally responsible for the infraction. .
 
gafftaper said:
The simple solution is to add a line to the rental contract which says, "Wireless equipment which uses illegal parts of the spectrum will not be used in our facility".

Seems like an important issue for all facility management to discuss. It seems likely that if the FCC came hunting someone down for using those frequencies they would hold the facility management equally responsible for the infraction. .
Click to expand...
I agree and it seems almost inevitable that someone will either claim to not know their systems were illegal to operate or to think the rules don't apply to them so it is probably not enough to just say it is prohibited, you also need a defined course of action should someone try to use such systems.

This is also one of those areas that to me ties to several other discussions in that if a venue requires users to use venue staff and especially to pay for them then the venue does accept some related liability as the 'operator'.
 
I'd be a bit more careful on the wording, but that's just me (and I'm not a lawyer). But if I were to add wording to the contract I might say something like:

"Tentant/Lessee/Whatever agrees to comply with all rules and regulations set forth in Title 47 of the Code of Federal Regulations and in Title 47 of the United States Code. In particular, lessee agrees to ensure that all wireless equipment is in compliance the Commission's rules. Lessee shall provide, upon request, documentation proving all wireless equipment used by lessee is in compliance with the Commission's rules."

You should require, essentially, a spreadsheet showing equipment model, operating frequency(ies), and effective radiated power, as well as a signed statement saying that all of that is legal (licensed or whatever).

"Illegal parts of the spectrum" is a pretty dubious statement... :)
 
mbenonis said:
I'd be a bit more careful on the wording, but that's just me (and I'm not a lawyer). But if I were to add wording to the contract I might say something like:

"Tentant/Lessee/Whatever agrees to comply with all rules and regulations set forth in Title 47 of the Code of Federal Regulations and in Title 47 of the United States Code. In particular, lessee agrees to ensure that all wireless equipment is in compliance the Commission's rules. Lessee shall provide, upon request, documentation proving all wireless equipment used by lessee is in compliance with the Commission's rules."

You should require, essentially, a spreadsheet showing equipment model, operating frequency(ies), and effective radiated power, as well as a signed statement saying that all of that is legal (licensed or whatever).

"Illegal parts of the spectrum" is a pretty dubious statement... :)
Click to expand...

For the most part that is pretty good, but ERP is not a commonly used specification with wireless mics, nor is ERP needed for proper coordination. If the equipment complies with the rules as stated in the first paragraph, that covers it.
 
Cashwalker said:
What's wrong with saying [-]"700[/-]26.54^2MHz" it's in the thread title.. what's with the math exercise as censorship?
Click to expand...

Technically it is illegal to use, just not to say. Although it is more entertaining that way. We are removing ourselves from that set of frequencies as much as possible.
 
Originally the thread title was self-censored (as "s***n") by the OP. It wasn't until a bit later that the actual number "700" appeared in this thread. I suppose we could call it the "698" band since that's where it starts, and several other bands (432, 144, 1296) are called out by their starting frequency; or we could talk about it by wavelength (40 cm).
 
Cashwalker said:
What's wrong with saying "700MHz" it's in the thread title.. what's with the math exercise as censorship?
Click to expand...
For once I try to not be so serious and look what happens. ;)
 
I thought we were talking about the frequency that's ~~ 0.11 × the number of people alive today... :twisted:
 
ScottT said:
I thought we were talking about the frequency that's ~~ 0.11 × the number of people alive today... :twisted:
Click to expand...

How foolish. We've been talking about .007 x 10^5 - 2 through radical 646,416 - 2.

cpf, what ever happened with the event? Did the 5.14^4hz devices work they way they had hoped?

museav said:
For once I try to not be so serious and look what happens. ;)
Click to expand...

It's amazing what happens!
 
I lobbied hard, but I'm not kidding myself in thinking that's what made the difference. The real trick was that, by pure luck, the head of the group that's sponsoring the production just happened to be watching a run-through with some particularly bad interference (think actors speaking through FRS radios with intermittent PTT switches). And just like that, well OK, after I dropped a few hints, a full Shure SLX wireless setup with E6 earsets (all rented) appeared at the next rehearsal.


I think now that they've seen the light of having good-sounding performers they might actually try to save up to buy a set or two for themselves. Everyone seems happy now, and I'll be talking with the facility manager about revising the rental contract :rolleyes:

As for the frequency obfuscation: I was poking fun at the sometimes overly critical and pedantic tone of this place. I believe I wrote a whole post about this a while back, but I can't find that now. Just imagine a long winded post about the relative merits of being harsh vs. risking giving people bad ideas.
 
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