fowlerrudi
join:2008-02-06
Fredericton, NB
| [Tech Ops] 900 mhz Floor Destroyed
Hello, I just put up a Mikrotik 900 mhz backhaul. I am using WaveIP gear (900mhz HVOL w/omni) to service my customers. As soon as I put up my 900 mhz backhaul (VPOL) 12.5dbi panel on the tower and to the other point 2.5kms away, my noise floor, when scanning through the WaveIP gear went through the roof. I've changed the channels (frequency) on the Mikrotik stuff, it improves, but not like as if it isn't there, it is still bad. How can I adjust channel spacing? How can I fix this problem? Thanks! |
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lutful
Premium
join:2005-06-16
Ottawa, ON
 ·TekSavvy Solutions..
| Even the best antenna designs provide only 20dB of separation between orthogonal polarizations. So if you are flooding an H-pol site with -50dBm level V-pol waves, it will see -70dBm noise floor. 
Maybe you can use 5Ghz or even 2.4Ghz backhaul?  |
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fowlerrudi
join:2008-02-06
Fredericton, NB | I've tried 5.2GHz, can't do it without LOS though. This is all NLOS. |
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viperm
Carpe Diem
Premium
join:2002-07-09
Winchester, CA | reply to fowlerrudi
What radio cards you using? can you reduce power? |
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fowlerrudi
join:2008-02-06
Fredericton, NB | Not sure, I believe XR9 Mikrotiks. I can reduce power, but then my signal strength will diminish correct? |
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LLigetfa
join:2006-05-15
Fort Frances, ON | You could deploy narrow bandpass filters on one or both. |
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mountain top
@earthlink.net | reply to fowlerrudi
Reducing the power is supposed to reduce the noise you receive from distant interference. You might reduce your signal but you might reduce your noise even more improving the quality of the link by increasing the SNR (Signal to Noise Ratio). |
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fowlerrudi
join:2008-02-06
Fredericton, NB | Good point mountain top, I shall try this. Aren't narrow bandpass filters expensive? |
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dongato17
VIP
join:2000-07-28
Atlanta, GA
| Are both of these radios using 20MHz of spectrum? If possible, you can try to change to 2x 10MHz channels and also run on different polarizations. This would give you polarization isolation as well as adjacent channel filtering to separate the links and could be enough to get the job done.
-Hal |
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fowlerrudi
join:2008-02-06
Fredericton, NB | I've got to figure out how to change the channel spacing first, I am new to these radios. The polarization is different from the other radios. |
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viperm
Carpe Diem
Premium
join:2002-07-09
Winchester, CA
| It should be under the wireless tab in winbox under band it should show you 900 Mhz 5, 10, 15 20 mhz if the radios support it..
--
ComTrain Certified Tower Climber. American Tower Certified approved contractor. Wireless consultants. |
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fowlerrudi
join:2008-02-06
Fredericton, NB | Mine are showing as 2432mhz, etc. It downconverts to 900mhz I am told. |
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viperm
Carpe Diem
Premium
join:2002-07-09
Winchester, CA | reply to fowlerrudi
AHhh probably so |
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LLigetfa
join:2006-05-15
Fort Frances, ON
| reply to fowlerrudi
said by fowlerrudi  :Aren't narrow bandpass filters expensive? Yes they are. You could try for greater physical separation and maybe erect some shielding to reduce sidelobes.
--
Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey |
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fowlerrudi
join:2008-02-06
Fredericton, NB | Physical separation won't help because when I sniff from 300 feet away from the tower (on the ground) with a subscriber unit, the noise is still there. |
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mtroup
Marty
Premium
join:2007-06-28
Hermitage, AR
edit:
July 5th, @02:01PM
| reply to fowlerrudi
Under the wireless tab look at "Band:" you should be able to select 2GHz-10MHz or 2GHz-5MHz |
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NZFxonet
join:2008-07-06
4814 | reply to fowlerrudi
What OS version are you running? I thought the newest versions displayed 900mhz correctly without the conversions.
Mike |
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Gerard780
Premium
join:2002-01-25
Simpsonville, KY | reply to fowlerrudi
Mikrotik only displays 900mhz when using the SR9's.
-Gerard |
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fowlerrudi
join:2008-02-06
Fredericton, NB
| reply to fowlerrudi
"if you go to the Wireless Tab of Winbox. You will see the "Band" drop down box. From here you can select 2ghz g (20Mhz0, 2ghz-10Mhz, and 2ghz-5Mhz."
Thanks a lot. I got it, had to change on both radios, for some reason I thought they'd sync. My spectrum is cleaning up! |
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