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Topic Author
Posts: 31
Joined: Fri Apr 09, 2010 8:50 pm

No frequency under -100

Fri Sep 23, 2011 9:10 pm

Hi all,

I have a 10KM link with 40M masts. I'm using 433+1000MW+17DB flat panel.

If i do frequency scan on side A (AP) it shows some good freq's to use (Under -80) but if i scan from side B (station) i don't get any freq's under -100.

Q: Why is that ? What can cause this?

I managed to connect it (After constantly changing bands and freq's) but the signal strength and throughput is not so well and currently is(AP):

Signal strength: 76-80 dBM
TX Signal strength: 60-62 dBM
Signal to noise: 10-20dB
CCQ: 50-80/50-70
Throughput: 10000-20000 kbps

* On side B i have more radio's installed (5GHz, 2GHz, FM) but i shut them down and tested and still the same
** I tried the same process with 3 different radio's per side
*** I tried to change configuration mode between AP and station
**** The signal and throughput above are my best results (after 2 days of headaches)
***** There is 30% difference in TX/RX frames vs HW TX/RX frames

Any help or advice will be highly appreciated.
Member Candidate
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Posts: 145
Joined: Tue May 18, 2010 10:06 pm
Location: Tyler, Texas USA

Re: No frequency inder -100

Fri Sep 23, 2011 10:30 pm

I am a newbe too. My guess is you have local interference on the B side. Not sure what you are saying about -80 and -100. If you are talking about the noise floor the higher -100 the better. If you are talking about signal strength then -80 and above -100 are not very good signal strength. lower is better. usually -75 is my cutoff. I have not tried NV2 yet it may work better in your case.
Forum Guru
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Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: No frequency under -100

Sat Sep 24, 2011 1:43 am

Your SNR (Signal to Noise Ratio) is very low. You should have better distance between noise floor and signal strength.
Probable cause is indeed interferences from either your other radios or from 3rd party.
If i do frequency scan on side A (AP) it shows some good freq's to use (Under -80) but if i scan from side B (station) i don't get any freq's under -100.
If the scan shows frequencies with lower than -80 it is better trying to avoid these. You should try to pick frequencies the scan doesn't even pick up. These are free for use. The other ones are in use and if you start to use these it is likely you will enter into problems. And off course, the better the signal the scan ´sees´ these other frequencies, the more likely it will cause problems if you start to use the same frequency.

If you put an export of the radio configs of both side we can take a closer look and see if there are also configuration issues at hand.

What is also important it the creation of radio links. Is the fresnell good and what about the LOS? You can have high towers but they should ´look´ at each other in-interrupted by any objects and even be free of objects that are coming close to the LOS.
Your distant should be easily be crossed with the hardware you'd use.
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Rudy R. Puister

WISP operator based on MT routerboard & ROS.

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