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Author Topic: Shure Groups and conflicts in WWB  (Read 640 times)

Alex Pregel

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Shure Groups and conflicts in WWB
« on: December 23, 2018, 10:38:48 pm »

Maybe I'm missing something, but WWB shows alot of intermod conflicts when I entered a group of transmitters using the same group.  I entered 20 ULX G3 units and assigned them to channels 1-20 in group 4. I know Shure claims that any channels within the same group will work together, but why does WWB say differently?
Attached is the results in Standard and "More frequencies" mode:
« Last Edit: December 23, 2018, 10:44:44 pm by Alex Pregel »
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Russell Ault

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Re: Shure Groups and conflicts in WWB
« Reply #1 on: December 24, 2018, 01:41:25 am »

Maybe I'm missing something, but WWB shows alot of intermod conflicts when I entered a group of transmitters using the same group.  I entered 20 ULX G3 units and assigned them to channels 1-20 in group 4. I know Shure claims that any channels within the same group will work together, but why does WWB say differently?
Attached is the results in Standard and "More frequencies" mode:

I'll take a stab at the first part of this: a lot of mid-tier wireless products (I seem to recall Sennheiser does the same thing in their G3/G4 microphones) don't seem to care about 3T3O intermods for their built-in groups. I'm guessing this is probably because you have to do something pretty stupid with a whole bunch of wireless mics to cause 3T3O-related drop-outs, and avoiding them requires a lot more spectrum, so by ignoring them you can increase your "number of compatible frequencies" marketing spec very cheaply.

As for your second screenshot (or the first one, for that matter): I'd opine that WWB's increased minimum spacing marks the difference between people who merely hope their RF will work (and just use the in-built frequencies) and those who will make their RF work (and do a coordination)...  :D

-Russ
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Scott Helmke

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Re: Shure Groups and conflicts in WWB
« Reply #2 on: December 25, 2018, 10:41:16 pm »

There also may be the additional effects from having TV stations specified under the Spectrum tab.
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Alex Pregel

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Re: Shure Groups and conflicts in WWB
« Reply #3 on: December 26, 2018, 12:16:18 am »

There also may be the additional effects from having TV stations specified under the Spectrum tab.

There were no exclusions included in the example. I get why they would ignore 3T3O but 2T3O and 2T5O can be fairly significant if you have a lot of mics that may be in pretty close proximity to one another (basically any large musical).
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Scott Helmke

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Re: Shure Groups and conflicts in WWB
« Reply #4 on: December 26, 2018, 12:23:33 pm »

My guess would be that WWB is somewhat paranoid by nature. For instance if you do a coordination based on exclusions from a frequency scan, it assumes that peaks in the scan are local and capable of causing intermod.

 It gives you options to reduce the checking ("More frequencies"), but it's your choice to do so. You can also go into the exclusions list one-by-one and change whether each exclusion is considered an intermod device.
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Jordan Wolf

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Re: Shure Groups and conflicts in WWB
« Reply #5 on: December 26, 2018, 03:08:38 pm »

My money is on those models being older technology, and the spacing and IMD calculations needing to be more conservative due to less-precise RF circuitry/tuning.
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Jordan Wolf
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Diogo Nunes Pereira

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Re: Shure Groups and conflicts in WWB
« Reply #6 on: January 11, 2019, 08:09:58 pm »

I know Shure claims that any channels within the same group will work together, but why does WWB say differently?

My guess would be that WWB is somewhat paranoid by nature.

My guess is the spacing settings (from other carriers and intermods) in WWB6's equipment profile for those ULX's are more conservative (or paranoid) than those initially considered to build the groups the units come configured with.

You can help WWB'S paranoia by tweaking the ULX equipment profile (in the Tools menu) to custom values that you find safe based on your experience with those receivers. Receivers with good selectivity reject carriers/IM close-by better than others, so spacing can be shorter, and you can then cram more frequencies in the same bandwidth.

I have no experience with the ULX's so I wouldn't know, but the "factory default" values for the ULX profile in "More Frequencies" mode is:

- channel spacing 425 kHz
- 2T3O 250 kHz

Your screenshots show no signs of "channel to channel" incompatibility, so it's all IM spacing that produce conflicts.

Open one of those conflicts (press the ">" symbol) in the analysis to understand what frequencies produce the fault with that specific carrier, calculate the arising IM product (2f1-f2), and that IM separation to the your imcompatible frequency. It should be of a lower value that 250kHz...



« Last Edit: January 11, 2019, 08:23:30 pm by Diogo Nunes Pereira »
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Diogo Nunes Pereira
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