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Author Topic: Clearcom Freespeak II antenna sheilding improves audio.  (Read 6734 times)

Pete Erskine

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Clearcom Freespeak II antenna sheilding improves audio.
« on: October 18, 2016, 02:39:02 pm »

These BBQ Pizza trays eliminated the fluttering we got when initially setting up here at the UNLV Thomas & Mack Center.  The roof here is a dome and, while not excessively high, does reflect back down to the floor all RF.  The aluminum screen is not grounded, just mounted above the antenna.  I'm thinking about suspending another 8" below to make essentially a doughnut pattern and keep reflections from going down when the antenna is mounted higher than 20' from floor.  The fluttering mostly would have gone away once an audience fills the arena but on this show there is virtually no audience -- most of the stadium is empty.

https://www.amazon.com/gp/product/B00EAXW1VY/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
« Last Edit: October 18, 2016, 04:14:47 pm by Pete Erskine »
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Scott Helmke

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #1 on: October 20, 2016, 09:58:34 am »

How high off the floor was the final position?
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Pete Erskine

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #2 on: October 20, 2016, 05:53:39 pm »

How high off the floor was the final position?

all 5 were about 15-20' up
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Marc Soame (UK)

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #3 on: October 21, 2016, 01:41:43 pm »

all 5 were about 15-20' up

Very interesting Pete, similar strategy to a 'black wrap' solution I've tried previously when encountering a metal concave roof. I've been musing further about creating a reflection blocker for these situations again by covering RF Blocking Material on a similar structure. I've looking at this material in particular:

http://www.aaronia.com/products/shielding-screening/Aaronia-X-Dream-100dB-shielding-fleece/


Marc
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Pete Erskine

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #4 on: October 21, 2016, 02:41:01 pm »

Very interesting Pete, similar strategy to a 'black wrap' solution I've tried previously when encountering a metal concave roof. I've been musing further about creating a reflection blocker for these situations again by covering RF Blocking Material on a similar structure. I've looking at this material in particular:

http://www.aaronia.com/products/shielding-screening/Aaronia-X-Dream-100dB-shielding-fleece/


Marc


interesting material but for the price and convenience the pizza trays are easier, I think.
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Pete Erskine
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Pete Erskine

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #5 on: October 25, 2016, 02:10:19 pm »

So, this week the FSII and Base2 are at a conference at the T-Mobile Arena.  The ceiling here is 190', 160' to the bottom of the steel so it's large.

Our stage is in the round, 36" high. We knew it would be a challenge due to reflections.  1 Antenna in each of the 4 voms about 1-2' back from the entrance made them work well.  Coverage did not extend to the center of the arena.  On 4 corners of the round stage (use your imagination) we put an antenna at about 5'.  As is the dropout was serious and unusable, even for just listening.  Placing a pizza screen on top of each antenna made it almost usable but the breakup was still very annoying.  Ultimately we had to move our main ASM and Stage crew to a BTR.

When off the floor the coverage is perfect, just not in the house.  Hopefully CC will come up with a solution.

In first pix you can see the FSII, the Mic antenna and on the railing behind, the white box, one of the 100+ wifi access points.  The last pix is one of the AP located around the stage.  We negotiated with the IT dept to keep them as far away as possible from our antennas.
« Last Edit: October 25, 2016, 04:06:07 pm by Pete Erskine »
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Ross Goldman (2)

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #6 on: October 26, 2016, 10:08:44 pm »

Thanks for sharing your experience. I had a very similar experience with FSII at the Anaheim Convention Center Arena, which although not as large as T-Mobile, does have a unique curved ceiling. In the hallways outside of the arena, quality was excellent. Inside, the breakup was pretty bad once you were about 20' from a transceiver. We experimented quite a bit with antenna placement inside the arena, with minimal improvement.

After the show, Clear-Com came out to the arena to do some tests and confirmed that the system was having trouble due to the ceiling reflections. We also demoed the 2.4 GHz version of FSII, which sounded great - zero dropouts. Apparently the 2.4 software deals with "errors" (reflections) differently than the 1.9 system. Hopefully, improvements can be made to the 1.9 software to better handle the reflections. It's a pretty great system aside from this issue.
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Ryan Trefethen

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #7 on: November 01, 2016, 02:22:15 am »

Hi Pete, great information.

I'm doing a corporate type show in the San Diego CC.  Using Freespeak II, latest version.  Having the same audio stutter problem as you describe.  I've used Freespeak on 3 other shows in very different environments and it worked great. Expected the same here.

It's a large space,not really square, more like a square next to a triangle.  500' x 300' with lots of hard surfaces, concrete floor. Most of the walls have a 8' high concrete finish on them. The air wall between Halls seems to be made of metal.

There are also 56 directional wifi emitters in this space transmitting a,c band at 5.3Ghz straight down as described by the Smart City techs we summoned for a conversation.  These are probably at about 45'.  Very nice people happy to help in any way as long as they didn't have to change the power, configuration of their perfectly working system. Which this particular high tech show would rely on for their 8000 attendees who surely would have at least 3 wifi hungry devices each.

The initial antennae design had 5 in the catwalk and 4 on the ground.

We implemented this original design and when we finally got to do some tests late on day two, realized the complete system had the audio stutter symptom.  We tried moving antennas closer to the users. We raised the antennas higher for better line of sight and nothing seemed to help.

I came back to the hotel with BTR's on an early morning order and very frustrated. And then I found this post. It encouraged me to try a few more things. I had not used this system in an arena and I saw the mention about deploying the antennas in the voms to shield from the reflections and multi path issues.

We basically put 4 antennas under the 45' x 200' stage near the areas that had the heaviest user traffic.  2 under tables that were needed in the main production tables, 1 under a table at FOH 300' from the stage but where a couple users would ultimately sit for the show and 1 under a table in front of the stage where a temporary tech table has been set for rehearsals.  We left one in the catwalk, somewhere in the middle of this space between the stage and FOH and even put a screen as Mr. Erskine shows to try to shield the antennae from the wifi emitters closest to it. This was just to get users to FOH.

This has dramatically upgraded our system, using the additional shielding of the stage and tables it brought our system usability up by 70%.  It has probably decreased our range a bit but seems to be working.

My question after all of this is, based on this scenario, what should I expect on show day when 8,000 attendees arrive with 24,000 + wifi devices.  How will my quality of service change and what improvements can I make to keep the integrity of what I already have.

Thanks so much,

Ryan Trefethen


Sent from my iPad using Tapatalk
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Pete Erskine

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #8 on: November 01, 2016, 11:36:43 am »


We basically put 4 antennas under the 45' x 200' stage near the areas that had the heaviest user traffic.  2 under tables that were needed in the main production tables, 1 under a table at FOH 300' from the stage but where a couple users would ultimately sit for the show and 1 under a table in front of the stage where a temporary tech table has been set for rehearsals.  We left one in the catwalk, somewhere in the middle of this space between the stage and FOH and even put a screen as Mr. Erskine shows to try to shield the antennae from the wifi emitters closest to it. This was just to get users to FOH.

This has dramatically upgraded our system, using the additional shielding of the stage and tables it brought our system usability up by 70%.  It has probably decreased our range a bit but seems to be working.

My question after all of this is, based on this scenario, what should I expect on show day when 8,000 attendees arrive with 24,000 + wifi devices.  How will my quality of service change and what improvements can I make to keep the integrity of what I already have.

Thanks so much,

Ryan Trefethen


Sent from my iPad using Tapatalk

You didn't say if you were using 1.9 or 2.4 FSII.  Neither should be affected by the audience.

In either case keep the antennas 15+' away from cell or WiFi antennas.  It's just good antenna practice.

The shielding I used was not to avoid antennas but to limit the reflection off of the ceiling which was almost 190' up.

is your catwalk antenna as high as the ceiling or how much room is above it?

I, too, went from a totally unusable system to one which was 70% with lots of dropout but mostly intelligible.
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Pete Erskine
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Keith Broughton

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Re: Clearcom Freespeak II antenna sheilding improves audio.
« Reply #9 on: November 01, 2016, 12:51:22 pm »

What is actually causing the "stuttering"?
Do I take it these systems are not diversity and as such, the RF signals are subject to (partial) cancellation due to the out of phase signals reflected signal from the ceiling?
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