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Coordination question

Discussion in 'Sound, Music, and Intercom' started by BCAP, Jul 14, 2018.

  1. BCAP

    BCAP Member

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    Hello,

    Does anyone have an opinion on whether it's better to let units such as Shure's ULX line "find" and self coordinate their own frequencies or whether it's better to use Workbench (or some other package) and calculate these frequencies then plug them in. I would be interested to know if there is a difference in the results - or, what the advantages / disadvantages may be.

    I use an RF spectrum analyzer and input that data into Workbench. I run some area scans, drop those into Workbench, then, I calculate frequencies and drop those into the units. And, I test. Usually, this works very well for me. But, I've run into a couple major issues recently that have me questioning whether this process is working the best it can and wondering whether I might get to a workable end result faster if I just use the finder functions on the units.

    Another question I have is if a setup is comprised of different offerings from different manufacturers (Shure, Sennheiser, AT) and different levels of frequency-agility, then is there really any option BUT to use software like Workbench to coordinate these units? It just seems to me to be way too complicated to use the unit functions, but I could be wrong on that.
     
    Last edited: Jul 14, 2018
    RonHebbard likes this.
  2. Aaron Becker

    Aaron Becker Active Member

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    I use the similar method of doing a basic freq coordination on my own. I leave "house" system stuff on their known-good channels and work around that. I've never used a standalone RF analyzier (meant to buy one, but then stopped doing as many RF based gigs and didn't see the point in spending the $).

    What type of issues are you having? Dropouts during performances? We'd need more details to know exactly what the issue is.

    I've used IAS for frequency coordination before, done multiple room builds, given the frequencies to the customer, and they've complained I gave them bad freqs. Nothing is perfect.

    Another method people use is "war-gaming" - (I found a good video https://www.rfvenue.com/blog/2015/06/03/video-how-to-war-game-transmitters) - you can skip to about 2:00 and watch how it works. I suspect the finder function of the receivers would need to combine some war-gaming technique anyways.
     
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  3. TimMc

    TimMc Well-Known Member

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    The math to calculate intermodulation is the same regardless of who wrote the software - the differences are how much of which harmonic products you want the software to calculate.

    Using an all-Shure setup with models that interface directly with WW makes this really simple. Using WW to calculate off line is more complex and you have to manually add the other manufacturers, models and freq bands.

    Starting freq is arbitrary whether selected by you or by software.

    There are a number of threads that deal with coordination here: http://forums.prosoundweb.com/index.php/topic,167843.0.html
     
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  4. FMEng

    FMEng Well-Known Member Fight Leukemia

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    Don't forget to use the latest version of software, because the RF environment is a constantly changing target. And it's already too late to use >600 MHz channels. The cell carriers are already lighting up what they can.
     
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  5. BCAP

    BCAP Member

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    Thanks for the opinions!
     
  6. Malabaristo

    Malabaristo Active Member

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    Your approach is solid, but don't forget that this is all a moving target because RF usage is often intermittent. Unless you're scanning continuously, there's no way to anticipate what new sources of interference may show up later. I would hazard a guess that the times you had trouble were cases where something new started broadcasting at some point after you did the initial setup.
     
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  7. BCAP

    BCAP Member

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    Thank you, and I totally agree.

    I have to say, I really like the "War Gaming" idea (thanks Aaron) and had I had time to implement that approach on my last job it might have helped. I think I'm going to try make that standard practice from now on, after I receive a set of candidate frequencies from software - and see how things go from there.
     
    RonHebbard likes this.

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