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Author Topic: Frequency Coordination video example  (Read 8502 times)

Pete Erskine

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Frequency Coordination video example
« on: August 28, 2015, 09:48:34 pm »

I rushed through this and didn't explain in detail what some of the IAS app was doing.  I wanted to show how easy and quick a medium size show could be coordinated.

Granted the city isn't Houston or Buffalo, two of the hardest cities to coordinate shows in but...

Please, If you have any specific questions I'd be glad to expand on the video.

Simple frequency coordination
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Pete Erskine
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Mac Kerr

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Re: Frequency Coordination video example
« Reply #1 on: August 28, 2015, 10:12:29 pm »

Thanks Pete.

Mac
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Thomas Harkin

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Re: Frequency Coordination video example
« Reply #2 on: August 28, 2015, 10:47:13 pm »

I rushed through this and didn't explain in detail what some of the IAS app was doing.  I wanted to show how easy and quick a medium size show could be coordinated.

Granted the city isn't Houston or Buffalo, two of the hardest cities to coordinate shows in but...

Please, If you have any specific questions I'd be glad to expand on the video.

Simple frequency coordination

Thank you. Thank you. Thank you.  I doubt, as a weekend warrior/HOW guy, that I'll ever need to do that.  But who knows?
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Justice C. Bigler

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Re: Frequency Coordination video example
« Reply #3 on: August 29, 2015, 01:22:40 am »

Oh...he heh...Tulsa, Oklahoma, huh?   ::)


IAS looks like it's a lot easier to use than RF Guru.


Thanks for the video Pete.


Can you explain the meaning of triple beats? In RFG I can never get enough open frequencies unless I turn the settings down to the lowest or second to lowest intermod settings.
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Pete Erskine

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Re: Frequency Coordination video example
« Reply #4 on: August 29, 2015, 11:05:35 am »

Can you explain the meaning of triple beats? In RFG I can never get enough open frequencies unless I turn the settings down to the lowest or second to lowest intermod settings.

Triple beat is IM distortion among three frequencies.  Two frequencies create 3rd order intermod frequencies.  A third frequency now not only interacts with the original primary frequencies making more 3rd order IM but the intermod frequencies as well making even more IM.  The number if created frequencies becomes large very quickly.

The worst IM is created in non linear amplifiers like the type used in RF combiners.  This is where the highest concentration of rf is mixed together and subjected to the non linearities of the amplifier making IM and 3IM.

So use tripple beat IM when selecting frequencies which will be actively combined.  Turn off the triple beat IM when searching for mic freqs since these freqs are not actively combined.

IM is created also when Transmitter antennas are near and each carrier is allowed to feed back into the others amplifier output.  Another reason to separate the TX antennas.  However because of the added loss of over the air RF the levels are much lower and even lower for triple beats.

Wireless mics can cause IM when sitting near each other on a table.  Ever try using a BTR beltpack near a table filled with wireless mics?  It doesn't work well die to the mess if OTA intermod.  As soon as these mics are separated by a couple of feet in use there is no appreciable IM. Always use baking tins for each mic to shield it from the other live transmitters.

If you are interested in more explanation  read this or for the math read this
« Last Edit: August 29, 2015, 11:11:45 am by Pete Erskine »
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Neil White

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Re: Frequency Coordination video example
« Reply #5 on: August 29, 2015, 03:08:13 pm »

So use tripple beat IM when selecting frequencies which will be actively combined.  Turn off the triple beat IM when searching for mic freqs since these freqs are not actively combined.

Pete,

Assuming that there is enough available spectrum for the number of required frequencies, does calculating for 3 transmitter 3rd order intermodulation for all transmitters, including Mics, produce a more robust overall co-ordination?

Has having the BTR belt pack TX in a separate zone ever caused issues with transient intermod affecting frequencies in the main zone?

Neil
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Pete Erskine

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Re: Frequency Coordination video example
« Reply #6 on: August 29, 2015, 04:16:46 pm »

Assuming that there is enough available spectrum for the number of required frequencies, does calculating for 3 transmitter 3rd order intermodulation for all transmitters, including Mics, produce a more robust overall co-ordination?

No  the additional triples have almost no effect on mics transmitters.  Won't hurt and if you get to the point where you run out of freqs, then turn it off.  More of a time saver, not more robust.

Has having the BTR belt pack TX in a separate zone ever caused issues with transient intermod affecting frequencies in the main zone?

Rarely the RX of the beltpack on the base falls on an intermod product of, lets say, and IEM frequency.  Then you will hear the IEM in the BTR but not be able to see it on a SA because it's so low.  Move the RX.  For this reason I try to do it in the same zone as much as possible and then if I have not enough BP TX freqs, I drag the Previously coordinated freqs into another zone and continue to add more. (you will get an error that your coordination is not valid - ignore.)

Choosing BTR Beltpack freqs with just the 3rd order on is sufficient.
« Last Edit: August 29, 2015, 04:23:28 pm by Pete Erskine »
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Neil White

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Re: Frequency Coordination video example
« Reply #7 on: August 29, 2015, 06:10:12 pm »

No  the additional triples have almost no effect on mics transmitters.  Won't hurt and if you get to the point where you run out of freqs, then turn it off.  More of a time saver, not more robust.

From the video it looks like IAS has global settings for the spacing to avoid 3rd / 3TX 3rd / 5ths intermodulation products, where as Shure WWB6 has this information as part of each equipment profile. What information does IAS track in its equipment profiles? Do you have a default set of values for these parameters that works with most equipment or does it vary with the quality and performance of the systems?
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Mac Kerr

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Re: Frequency Coordination video example
« Reply #8 on: August 29, 2015, 06:16:09 pm »

From the video it looks like IAS has global settings for the spacing to avoid 3rd / 3TX 3rd / 5ths intermodulation products, where as Shure WWB6 has this information as part of each equipment profile. What information does IAS track in its equipment profiles? Do you have a default set of values for these parameters that works with most equipment or does it vary with the quality and performance of the systems?
Attached is the edit window for individual hardware profiles. The "Presets" tab just displays all the available frequencies.

Mac

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Tom Bourke

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Re: Frequency Coordination video example
« Reply #9 on: August 29, 2015, 08:09:39 pm »

How does IAS compare to wireless workbench for quality?  I have used WWB6 here in Las Vegas and had good results.  Others claim it does not work at all here.  I will admit that some of the set-ups it said would NOT work do.  I attribute that to our wireless being spread out over a very large area.  I normally deal with convention set-ups so I will have lots of rooms/zones with less than 5 microphones in them.
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