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gcs
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Noise floor

Wed Aug 21, 2013 9:56 pm

I have a 150' tower which has been working fine for 5 years. In the last 2 weeks I have been having problems with the 900 mhz on that tower. The noise floor usually has been in the mid 90's. Now it drops to 50's for a few seconds then returns to mid 80's or higher. Yesterday it worked almost all day fine but today it started up again. I climbed the tower and replaced the 900 radio card and it did not change anything.

I went back up to 60' with a 900 and yagi antenna and never had the floor drop. it was mostly in the 90's to 100 even while the tower dropped.

Any Idea what is going on and how to find and fix it?

Thanks for your input.

David
 
jaykay2342
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Re: Noise floor

Thu Aug 22, 2013 7:26 pm

Is it possible that some one else has started to use 900mhz in the same area?
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gcs
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Re: Noise floor

Fri Aug 23, 2013 6:37 pm

I don't think so. now several of my towers are doing the same thing. floor drops to 50's for a while the goes back up for some time. it seems random and the up time may be minute or less or 12 hours especially at night.

I am getting a specturm analyzer to see if I can find anything out.

Thanks
 
jaykay2342
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Re: Noise floor

Sat Aug 24, 2013 1:20 pm

I am getting a specturm analyzer to see if I can find anything out.
yeah i think that's the best way to troubleshoot this issue. everything else is just guessing around and try and error and that's not a professional way at least in my opinion
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ne0031
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Re: Noise floor

Wed Sep 04, 2013 7:51 pm

Oh the woes of 900.

6 years ago we put up loads of 900 links. Now there is only 1. Frequency hopping radios were our cause and exhibited the same type of behavior you are describing. We have analyzers, so we quickly determined the sources.

Nothing you can do if that is the cause.

Our first culprit was smart grid. The power company implemented 900mhz meters. That was followed by traffic radar reporting for automated speed tracking on everything down to neighborhood roads - gotta be able to show which roads are congested.....
Matt

ABC/WXYZ - you get the picture.....

150khz-110ghz
1/5sps to 4gbps

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