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Author Topic: Need Help / Suggestions For IEM RF Issues  (Read 4374 times)

Ike Zimbel

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Re: Need Help / Suggestions For IEM RF Issues
« Reply #70 on: November 14, 2017, 10:50:20 am »

I had a bad day at the office a couple days ago!!!! And it only supports my theory on RENT FROM LOCAL PROVIDERS.

I was doing a show for Ready Pac. We had their CEO's giving a little pep talk to about 250 employee's at the plant. Did not 1, but 2 RF scans and came up with the same results both times. Off we go. Something changed from earlier that morning til the time it was too late to do anything about it. After the room filled with people the body packs distributed and on, the RF lights are dancing like a bouncing ball to a song. Except for the rented units that were another band...... The rented units were from a local provider and were in the 400 band while the company owned ones were in the 600 band. We were only 50' away and with directional paddles and still no diversity..... Needless to say we had to swap a body pack mid presentation because of dropouts.

RF can change on a whim. What changed I am not exactly Shure...... but I was not happy and neither was my boss or the client. You can do everything right and still throw a bomb every now and then. I didn't have Wireless Workbench because we didn't have all the RF networked so I had to do the old fashioned scan one unit, turn on the packs and then scan the next units etc. Turn off all units and see how the noise floor looks. In my case all was great until it was too late.
Sounds like NO FUN. A few points / questions come to mind:
1) Were you using Shure paddles, and if so, which model and what gain setting were they on? If they were the old model, the +3db setting would have been the preferred setting (although NO gain would be best). With the new ones, 0 or -6db. Too much gain is not your friend, ever.
2) WWB can be used to coordinate a set-up, even if all of the units are not networked. With just one unit connected you can do a scan (although only in the range of the unit). In this case, the 470MHz rental gear would not have been included in your scan. In any case, even without a scan you can use the coordination tab to come up with a list of coordinated frequencies for all of the units.
3) Scanning one unit at a time is better than nothing, but it is not a coordination. The only "coordinated" way that can work is if you scan one unit, let it find the Group that has the most available frequencies, and then allocate it and the other channels into that Group, and only that group. Once you go out of the group, you are off-roading.
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~Ike Zimbel~
Wireless frequency coordination specialist.
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Terry Martin

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Need Help / Suggestions For IEM RF Issues
« Reply #71 on: November 22, 2017, 09:14:30 pm »

Well thought Id post an update.  However, I dont want to jinx myself.  I purchased an RF Explorer and Vantage software.   I also put the X32, IEM units, and combiner in the same rack that I had the A&H analog board in - mounted in same locations.   Mixer is separated from IEMS due to slant portion of rack not contacting vertical rack. Used same Omni Sennheiser remote antenna.  We played 2 locations last weekend.  ...about 100 miles apart - and weve had light RF hits at both locations in the past.  I scanned the stage area, exported the scan to WWB, loaded the recommended freqs and no RF hits as wed had in the past.  We will play the venue where we have had sharp / painful RF hits in a couple weeks (the mall o / bar o rama- lol).  That will be the real test.  Im hoping this has been a coincidental RF coordination issue.   ....and I can go back to the 12 space rack that makes much more sense.  I hate to have to coordinate every night - but maybe thats where we are at in todays world (bar band world).  We dont have the staffing nor time usually to conduct coordination.  But oh well, its worth not having the RF hits. 

Im doing load in for Pop Evil on Friday afternoon (at the mall o / bar o rama - I will be paying close attention to their RF situation there.   Hopefully Ill have time to ask questions.
« Last Edit: November 22, 2017, 09:16:31 pm by Terry Martin »
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Dan Mortensen

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Re: Need Help / Suggestions For IEM RF Issues
« Reply #72 on: November 23, 2017, 01:29:02 am »

Use of an RF spectrum analyzer showed a big RF spike from a bad cable or termination of a cable connecting to an SDI device.

So, Tim (or anyone else), how would you use a spectrum analyzer to localize that spike to identify a particular cable or end of a cable?

Is there some kind of special antenna?

Cables spraying interference is a phenomenon I've never heard of in my very limited experience.

There has been talk elsewhere (maybe on this forum?) about unterminated ports being some kind of problem, but have not heard of a solution (what does a terminator for an unterminated port look like?) or exactly what kind of problem it is.

Well, shoot,  Google is your friend

Terry, you got any unterminated RF ports in your rack? Could that result in spraying RF interference around?

I'm glad that Terry is checking back and has gotten an RF Explorer and Vantage to try to figure it out. It's been interesting to read through the whole thread again, with a problem that is vexing the experts as well as the newbies.

I don't doubt that a solution will be found and that it will be helpful to all of us to know the answer.
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Terry Martin

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Re: Need Help / Suggestions For IEM RF Issues
« Reply #73 on: November 23, 2017, 08:36:37 am »

All of my RF ports are terminated by cables/antennas or antennas directly on the units. 
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Jean-Pierre Coetzee

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Re: Need Help / Suggestions For IEM RF Issues
« Reply #74 on: Yesterday at 06:36:27 am »

By cables or antennas?

You mean that there are cables run with nothing on the end. By definition that is an antenna.

Honestly it looks like a coordination issue regardless and is no solved.

Sent from my 2014817 using Tapatalk

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Terry Martin

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Re: Need Help / Suggestions For IEM RF Issues
« Reply #75 on: Yesterday at 08:09:42 pm »

No, if there is a cable attached to the unit, it is connected to an antenna. 

Some of the units on stage have antenna(s) connected directly to the unit. 

There are no open RF ports / cable ends. 

You might be right - it could very well be a coordination issue.  Why would you say its not solved - did I miss something in the scan or WWB setup?

By cables or antennas?

You mean that there are cables run with nothing on the end. By definition that is an antenna.

Honestly it looks like a coordination issue regardless and is no solved.

Sent from my 2014817 using Tapatalk
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brian maddox

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Re: Need Help / Suggestions For IEM RF Issues
« Reply #76 on: Yesterday at 09:47:33 pm »

No, if there is a cable attached to the unit, it is connected to an antenna. 

Some of the units on stage have antenna(s) connected directly to the unit. 

There are no open RF ports / cable ends. 

You might be right - it could very well be a coordination issue.  Why would you say its not solved - did I miss something in the scan or WWB setup?

I think he meant noW solved?  But could be noT solved.  One letter, opposite meaning. Love this language...
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brian maddox
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