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Title: The GLD's RF footprint
Post by: Mark McFarlane on March 20, 2014, 05:17:28 PM
I was playing around with WSM and my newish GLD and had some interesting results I thought I would share. Hopefully the pics are self explanatory.  I reran the tests twice and got repeatable results, with some slight variations between tests over the night, but essentially the same results.


My conclusion:  Keep the wireless receivers away from the GLD. How far is for another night of testing. 


Normally I would put the wireless RX on stage but am hoping to use the 4 extra inputs on the GLD for times when I need more than the 24 channels of the AR2412.
Title: Re: The GLD's RF footprint
Post by: Mark McFarlane on March 20, 2014, 05:22:48 PM
Here's the setup.  For the measurements posted above I lifted the wireless receiver another 2' higher using some boxes.
Title: Re: The GLD's RF footprint
Post by: Mac Kerr on March 20, 2014, 05:51:30 PM
I was playing around with WSM and my newish GLD and had some interesting results I thought I would share. Hopefully the pics are self explanatory.  I reran the tests twice and got repeatable results, with some slight variations between tests over the night, but essentially the same results.

It's not too surprising that digital electronics put out RF. I guess you found a place to not put your RF mics.

Mac
Title: Re: The GLD's RF footprint
Post by: Jeff Carter on March 20, 2014, 07:20:47 PM
I was playing around with WSM and my newish GLD and had some interesting results I thought I would share. Hopefully the pics are self explanatory.  I reran the tests twice and got repeatable results, with some slight variations between tests over the night, but essentially the same results.


My conclusion:  Keep the wireless receivers away from the GLD. How far is for another night of testing. 

Interesting. Did you measure with the GLD powered on and the AR2412 off to confirm that the GLD is the primary culprit? (It's entirely possible that both boxes need to be powered up to cause the interference if it's associated with data transfer on the CAT5).

Next gig it might be interesting to measure the noise both in the vicinity of the stage box and the GLD as another check.

In my church, we decided to keep our existing analog snake rather than pull the cat5 (no conduit from FOH to stage of course), so the AR2412 and AR84 live at FOH. Originally, we had them in a 6U rack right underneath another 6U rack with all the wireless RX. Our 700 MHz Shure UC-series beltpacks* never had any issues with this arrangement but our SLX packs in the 500 and 600 MHz bands had no end of dropouts until we moved the RX on those units to stage.

*700 MHz was legal up to April 2013 in Canada, about 6 months after we bought the console--we shut those units down at that time.
Title: Re: The GLD's RF footprint
Post by: Cameron Stuckey on March 20, 2014, 07:22:55 PM
Here's the setup.  For the measurements posted above I lifted the wireless receiver another 2' higher using some boxes.

What's the status of the Airport during these tests? Are you monitoring the GLD when it's on over wifi? I don't doubt that the console generates noise but I've seen access points do so too.
Title: Re: The GLD's RF footprint
Post by: Mike Pyle on March 20, 2014, 11:21:41 PM
I'd be interested in knowing if the proximity to the display on the GLD affects the results.
Title: Re: The GLD's RF footprint
Post by: Mark McFarlane on March 21, 2014, 12:01:05 AM
What's the status of the Airport during these tests? Are you monitoring the GLD when it's on over wifi? I don't doubt that the console generates noise but I've seen access points do so too.
WAP Effect

The airport is on for all 3 tests, so it's impact is minimal in the top graph.  Below are tests with the console off, and only WAP on. 3 WAPs shown, Airport Extreme, Airport Express, and DLink DIR-815.  These results are better than I expected, and 'good' because the Airport Express will live in the case with the ew300 on stage.


I did a similar test 2 years ago with a Belkin N600 router and it was almost as noisy (rf wise) as the GLD.
Title: Re: The GLD's RF footprint
Post by: Mark McFarlane on March 21, 2014, 05:21:13 AM
EW300 at 69"


Here are two tests with the ew300 69" from the top left corner of the console, at ~30 degree angle.  Still quite a bit of noise at 5' + over half the band of my wireless mic system
Title: Re: The GLD's RF footprint
Post by: Mark McFarlane on March 21, 2014, 05:27:11 AM

EW on left versus right of GLD

And finally, the result of placing the RX to the right versus left of the GLD.  Left side is definitely quieter.


The last two graphs look suspicious to me, I'll need to rerun the tests sometime.
Title: Re: The GLD's RF footprint
Post by: Mark McFarlane on March 21, 2014, 05:48:55 AM
Besides all the purdy graphs, perhaps the 'real question' in all of this: "How many db above background noise level can one safely operate a wireless mic?  10db? 20db? 30db? 40db?"

It looks like I can possibly place the ew300 on a stand just to the left of the console, in cases where I can't have it on stage.
Title: Re: The GLD's RF footprint
Post by: RYAN LOUDMUSIC JENKINS on March 21, 2014, 09:07:08 AM
Besides all the purdy graphs, perhaps the 'real question' in all of this: "How many db above background noise level can one safely operate a wireless mic?  10db? 20db? 30db? 40db?"

It looks like I can possibly place the ew300 on a stand just to the left of the console, in cases where I can't have it on stage.

For the last year or so I have been doing events for a particular customer where I must keep all the electronics inside my trailer to protect the gear.  My GLD is about 24" from the wireless mics and the two amp racks.  For wireless I use either ULXP or MiPro.  In most instances the MiPro seem to be better except in the trailer with the other gear right there.  Generally speaking my range using plain old 1/2 wave antenna is about 100-150' with the ULXP where as I only get about 100' max with the MiPro at these events.  I don't hear any of the RF noise in the system however I can see it on the RX meters.  For high end musical events I would prefer not to have the wireless receivers that close to the console but you do what you have to do.  These ones are just an emcee talking and it is just fine.
Title: Re: The GLD's RF footprint
Post by: Scott Helmke on March 21, 2014, 10:14:58 AM
Did you try measuring close to the Cat5? I was at a manufacturer training seminar (Lectro, maybe - they're doing a lot of Dante) and they recommended shielded Cat5 to keep the RF from radiating.
Title: Re: The GLD's RF footprint
Post by: Mark McFarlane on March 21, 2014, 02:02:36 PM
Did you try measuring close to the Cat5? I was at a manufacturer training seminar (Lectro, maybe - they're doing a lot of Dante) and they recommended shielded Cat5 to keep the RF from radiating.

I used unshielded Cat 5 for the connections between the ew300 and the WAP.  dSNake was on the short purple cord that comes with the GLD.  Dante card wasn't connected for these tests.

I didn't explicitly test proximity to Dante and DSnake cables.