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kameelperdza
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Signal not improved when changed from 2.4ghz to 5ghz :-(

Thu Feb 05, 2009 12:53 pm

Hi i bought two 5ghz 24dbi grids and two r5h cards. The noise is still -91 tp -89. What i have heard is that the r5h has a filter that can block unwanted signals. But the noise is stil very high. With my 2.4ghz 24dbi grid i got -84 when just using a 100mw and a 400mw card. The r5h's are both 320mw. But the noise is still to high. I also made the cable shorter for less db loss. What can i do. And is the card running 320mw by default or must i setup it to run 320mw. thanx
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Mon Feb 09, 2009 4:12 pm

kameelperdza -

It is not so much the noise floor as it is the difference between the noise floor and the received signal - this is called Signal-to-Noise ( S/N ) ratio. What you are looking for is about 20db or more between the noise floor and the received signal, i.e.,

received signal = -65db, noise floor= -90db, S/N = 25db, this is good.

received signal = -85db, noise floor= -90db, S/N = 5db, this is not good....

Understand?

R/
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kameelperdza
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Fri Feb 13, 2009 9:36 am

my floor noise is -103 mysignal strength is between -79 to -85. my db is between 14 - 23. At the moment my singal strenth is -82dbm ,the signal to noise is 22db. i was using channel 5775 but got becon not recieved errors when transfering large files. So i set the channel lower but it got. even worse. So i decided why dont go higher, i set the channel to 5758. And now it is much better with no errors. Im running on the 5ghz-10mhz freq. When i try to use turbo mode then the AP cant connect.
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Fri Feb 13, 2009 8:24 pm

kameelperdza -

Sounds like you need to use higher gain antennas - your received signal strength -79 to -85db is getting close to what the cards are will to work with at all.... I believe the R52H best receive sensitivity is either -92 or -95.....

R/

Thom
Thom Lawless
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kameelperdza
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Sun Feb 15, 2009 5:00 pm

thanx but im going to move to a new location soon. Hopefully ill get better signal
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janisk
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Mon Feb 16, 2009 10:16 am

wider the band - and higher the possible data rate - weaker the signal, as a result if your data rate goes up to 54MBps (air rate) output power decreases, the same is happening in turbo mode where band is even wider, thus you cannot connect at all.
 
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kameelperdza
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Mon Feb 16, 2009 10:14 pm

i get 36mbits when using the r5h card on channel 5830 running 5ghz 10mhz
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janisk
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Tue Feb 17, 2009 11:48 am

you are getting maximum that 10MHz channel is capable of

what version of routeros you are running? try newest if you are not and check if you see any improovement
 
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Wed Feb 18, 2009 7:15 pm

Have you ruled out possible obstructions in your path?
Do you have clear line of sight between the endpoints?
 
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kameelperdza
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Wed Feb 18, 2009 9:14 pm

Im running routeros version 3.20. I have some trees in the way.
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fatonk
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Thu Feb 19, 2009 9:37 am

What is the distance of this link ? and do you have any obstacles in the Fresenel Zone refer to: http://www.zytrax.com/tech/wireless/fresnel.htm

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Faton
 
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kameelperdza
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Re: Signal not improved when changed from 2.4ghz to 5ghz :-(

Thu Feb 19, 2009 10:25 am

thanx i have read the link. I am trying to use fresnal zone 1. I cannot see the other end(antenna). The only thing that is in the way is the trees. There are no big buildings. maybe a school that have 2 floors. There are big trees. I had the same angle on the antenna's with my senao routers. The sped was great but woth the mikrotik it is as if im using a 56k dailup.
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