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Author Topic: On-site Cell Tower Interference  (Read 5530 times)

Brian Ehlers

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On-site Cell Tower Interference
« on: October 03, 2012, 06:50:26 pm »

My House of Worship is considering allowing Verizon to install a cell phone transmitter/antenna in our tower.  The attraction for us, of course, is the lease $$$ we will earn.  My immediate gut reaction is "Keep that stuff away from my PA system!!!"  Yet I've never heard anyone complain of problems, and I know that a lot of churches do such an installation.

So my question is, do any of you have any experiences -- good or bad -- with installing a cell phone tower on the premesis?  I'm not worried only about the PA system but all other electronics in the church.  I realize that the cell frequencies are unique, but I'm worried about the transmitter's high power overloading vulnerable devices.
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Hal Bissinger/COMSYSTEC

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Re: On-site Cell Tower Interference
« Reply #1 on: October 03, 2012, 07:28:06 pm »

Well, it's not high power and I've never heard of anybody having problems with anything in the building or adjacent buildings. I wish a cell company would knock on my door and offer me $$$ to locate a cell site on my roof.
 
-Hal
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Henry Cohen

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Re: On-site Cell Tower Interference
« Reply #2 on: October 03, 2012, 10:03:56 pm »

It's highly unlikely the cell site will induce RFI problems with any properly designed audio equipment, or any other system inside the building.

First, cellular/PCS sector antennas are highly directional. Directly below the antenna is a major null with signal levels easily being 50-70dB below on axis carrier level (based on antenna type and design) before building attenuation is considered.

Second, you can request engineering data from the cellular/PCS service provider(s) and/or tower management firm which will tell you antenna make(s) and model(s), antenna array(s) design, location(s) and ERP of each TX antenna. An outside RF consultant can assist in determining RFI potential.
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Henry Cohen

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Tom Young

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Re: On-site Cell Tower Interference
« Reply #3 on: October 04, 2012, 10:55:36 pm »

My House of Worship is considering allowing Verizon to install a cell phone transmitter/antenna in our tower.  The attraction for us, of course, is the lease $$$ we will earn.  My immediate gut reaction is "Keep that stuff away from my PA system!!!"  Yet I've never heard anyone complain of problems, and I know that a lot of churches do such an installation.

So my question is, do any of you have any experiences -- good or bad -- with installing a cell phone tower on the premesis?  I'm not worried only about the PA system but all other electronics in the church.  I realize that the cell frequencies are unique, but I'm worried about the transmitter's high power overloading vulnerable devices.

Over the past 4 years 6-7 of my church clients have leased their steeples to cellphone companies. All use wireless systems and also have racks close to the steeples. There have been no problems what-so-ever with any noise.

Actually ..... there was one problem with one church. While installing below-ground cable (AC power lines ?), the backhoe operator hit a gas pipeline. Within 15 minutes there were fire trucks, cops and EMT swarming..... enforce. Then someone from the gas company showed up.

You should be fine.
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Tom Young
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Chris Eddison

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Re: On-site Cell Tower Interference
« Reply #4 on: October 05, 2012, 12:11:35 pm »

At least with the base station its' location and activity is predictable. The major hassle with mobiles is they're forever moving, changing their power level depending on their range and generally doing unpredictable things. Probably far worse having phones around the desk moving and polling, than one mast sat on top of the building.

Mobile phone antenna design aims to direct as much power as possible (and receive as much signal as possible) in the places where it's needed - normally outwards - all in the name of efficiency. They use some very clever phased arrays to push the polar patterns out. This tends to mean above and below the antenna contain nulls anyway, so you may actually be far better off being in the church with the mast on top, than saying no and letting them install it on somebody else's building nearby instead!

One thing to consider will be that you'll effectively loose access to the tower in front of the aerials as it's deemed unsafe to be in front of them while radiating. Not an issue for your sound, but maybe one your building maintenance people should think of.

Over this way, if there's an interference complaint then 9 times out of 10 it ends up being the complainant's equipment that's sub standard when it comes to rejection, rather than the transmitting equipment that's out of spec.
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Brian Ehlers

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Re: On-site Cell Tower Interference
« Reply #5 on: October 05, 2012, 06:40:38 pm »

Thanks for the great responses, guys.  I appreciate you sharing your experience.

I knew there's supposed to be a null directly under the antenna, but you know how things aren't always the way they're supposed to be.....

Quote
Actually ..... there was one problem with one church. While installing below-ground cable (AC power lines ?), the backhoe operator hit a gas pipeline. Within 15 minutes there were fire trucks, cops and EMT swarming..... enforce. Then someone from the gas company showed up.

There was a similar situation here a few years ago.  All the first responders were smart enough to stand back.  But when the gas company guy finally showed up, he parked his truck too close to the leak.  KABOOOOM!!! 
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Aram Piligian

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Re: On-site Cell Tower Interference
« Reply #6 on: October 09, 2012, 02:24:29 pm »

One 'gotcha' for anyone else reading this that might come across this post in the future... Verizon towers operate in the 700 mhz range that was made illegal some time ago.  Now, while theoretically all 700 mhz mic transmitters and receivers are out of operation, houses of worship (and schools) are occasionally inclined to pay no attention to such issues.  In that case, I imagine that a tower operating in that range would cause some problems.  But in that case, it's just another reason to get legal gear!
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ProSoundWeb Community

Re: On-site Cell Tower Interference
« Reply #6 on: October 09, 2012, 02:24:29 pm »


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