Help identifying this tone when using GMRS Repeater

[Guest entropywrench@gmail.com]

Hello all. 
Helping a buddy set a GMRS repeater up in the middle of the woods to see if the system will work for an upcoming event.
Our weekend test was a bit of a bust. Several of the test radios from various makers didn't reliably hit the repeater.  
Then sometimes they did, then didn't again.  Then most would but one wouldn't. Head scratching... 
All through the testing process this "tone" would start up and sometimes babble through all the radios for up to a minute. 
I should know the noise carried through our testing area better than anything else.
I'll add a link to a 12 second audio file at the bottom.

Equipment was a Retevis RT97 and a "slim jim" antenna strung 40 feet into a tree. 
We toyed with privacy on/off open repeater different channels, transmit powers, etc.
Couldn't find a combination that worked for our purposes nor could we recreate this tone on demand. 
We assume it's coming from the repeater as when we configured the test radios to not use the repeater at all. No noise just expected range issues.

Anyway, we are testing all cables, antenna, etc but in the meantime, I'm hoping you all can can help identify what that noise is what could be causing it.

12 Second Static and Unidentified tone 

Thanks in advance, Mike.  

[SteveShannon]

404 - file not found. Probably a permission thing. As a guest you might not have permission to upload files. 

[entropywrench]

Yup, I noticed that, so I registered and trying again with a direct upload and a link from G drive.
 

Offending audio in question linked and attached here:  
https://drive.google.com/file/d/1cuIFnbH_eVS-tK4AAoTZZDrSx75JxyJJ/view?usp=drive_link

Between the two it should be ok.  

My friend did hook the antenna system up to an SWR and was getting strange results. To the point where he's ordering a more specific meter. 

[OffRoaderX]

That does not sound right.  Was the signal of the noise strong, like it was coming from the repeater, or was it weak like it was something far away?

..and, poor SWR would have nothing to do with this noise, but what do you mean by "strange results"? What was the SWR reading? and what do you mean by "more specific meter"? 

[entropywrench]

It was a very strong signal and discernible from the predicted ranges of the repeater even when voice didn't work. 
We tested the radios with straight gmrs (not using the repeater) and the tone never showed up. 

The strange sound appeared with Privacy Tones On or Off. 
 
As far as the SWR, he said it was "off the charts" on the Slim Jim Antenna and when he tested his fiberglass antenna back at the farm it read "8"
However, the SWR was not for UHF so those results should probably be ignored. 

So far he's not been able to reproduce the tone back at the farm. Same repeater, same portable battery, same coax, and slim jim Antenna. 

So far though, I appreciate the help.

 

[LeoG]

Sounds like you are trying to connect to AOL by phone.

[marcspaz]

That is the sound of telemetry data, while listening to it with an analog receiver. Its very common to hear on FRS/GMRS channels in rural areas where farming is mostly still family run and they don't have big budgets for automated monitoring and control systems.

[entropywrench]

Well, maybe some logging equipment as there isn't a bit of farmland in quite some distance, well beyond the repeater. 

I here's a google maps pin of nearish were we tried the repeater.  

To further add some details, we would hear this noise on 20 or 22 repeater only with our without privacy.

https://maps.app.goo.gl/ZKxaU34Jv3kgCZ7y9   <-approximate repeater location

[OffRoaderX]

Do you hear this noise when the repeater is turned off?

[marcspaz]

Yeah, that is very odd. Privacy tones make it so you can't hear a signal unless the tone is present. You should hear the signal with no tone and it should go away when the tone is enabled, unless your radio is broken. That could be possible. You hear noise when tone squelch is enabled because the radio is broken, and you're just hearing random noises from the radio itself. 

[WRUE951]

would be interesting to get a spectrum analyzer on the signal and also try to get a heading in he direction it is coming from..  Is this signal continiouse or dependable enought ot track down..   Are you getting it on one chanel? or several channels in GMRS?  What Ch were you setting yiour repeater up?   Did you try another? I wuoild have fun tracking that one..  wish i could help, but to darn far away to hitch up and go 

[entropywrench]

We did not hear the noise when the repeater was off.

We got it on 20 and 22 when we tested. Didn't try any of the other lower power channels.

Only had the one repeater to play with. 

I toyed with squelch from 0-3 didn't seem to make a difference, the noise was always able to break the squelch

We couldn't "make" it happen, sometimes it would be just a few seconds. Another it went on for more than a minute.

All in all we had 6 hand held radios of various makes, a truck based radio.
 

The tone didn't appear when we would scan all the GMRS, MURS,etc frequencies save for the current repeater channel