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ste
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SXT Polarization

Fri Feb 18, 2011 9:56 pm

Sxt has Chain0=Hpol Chain1=Vpol.
What happens when connecting to a sector which
has Chain0=Vpol Chain1=Hpol?
 
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Belyivulk
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Re: SXT Polarization

Sat Feb 19, 2011 7:07 am

Id be interested to know as well - it SHOULD work, no?
 
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normis
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Re: SXT Polarization

Mon Feb 21, 2011 7:50 am

for 802.11n it doesn't matter at all. All that matters is that you align the antenna in proper polarization.
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karlos
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Re: SXT Polarization

Mon Feb 21, 2011 10:14 am

Normis Are you sure ?

We had an migration issue on 52=>52N link

Originaly:
(AP side) RB133 + R52 <--> RB433AH + R52 (Cleint side) modulation 20MHz 802.11a

upgraded to 5.0rc7 -
result OK

Than upgraded card on cleint side
(AP side) RB133 + R52 <--> RB433AH + R52N (Cleint side) modulation 20MHz 802.11a
but the technician used chain 1 output, not chain0 because cable lenght issue, but selected chain1 as used output in software
result - OK

Next tryed another change
(AP side) RB433AH + R52N <--> RB433AH + R52N (Cleint side) modulation 20MHz 802.11a
wirelless link established, signal -49 to -52dBi, wirelles shows 50km or over distance, change to 802.11n or nv2 modulation does mnot help at all
result - 99% loss of data, nearly no troughput

FIX
Changet output on client side from chain1 to chain0 on card and even in software
distance shows better value 2km (its 1,2km), CCQ 92-100%, good troughput, no loss, possible to run on 802.11a, 802.11n and at nv2 too
result - OK


So the question is why? I know we schould not connect it this wrong way another time, but the question is still there.
 
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normis
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Re: SXT Polarization

Mon Feb 21, 2011 10:17 am

The original question was about using both chains, but in reverse polarizations.

You can't use Chain1 only. You need to use either Chain0 only, or both chains.
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karlos
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Re: SXT Polarization

Mon Feb 21, 2011 10:41 am

Thank you for answer.

Why does it work on combination of R52card and R52N card using chain1, and does not on two R52N cards using standart 802.11a modulation?

My idea was that the chain0 is like leading or controling and the chain1 is something like follow-up information for room multiplex and more troughput. But this should work just in 802.11n but not in 802.11a.... or i am wrong ?

I know how to do it right. We will never made this mistake again. I always wanted to understand how things work.
 
uldis
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Re: SXT Polarization

Mon Feb 21, 2011 11:41 am

as Normunds stated you need to use chain0 first and use chain1 as it is optional.
It doesn't matter if it is A or N, you need to use chain0 first.
 
ste
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Re: SXT Polarization

Mon Feb 21, 2011 12:32 pm

To make it clear:

Chain0 has to be rx-enabled. It is possible to disable tx on chain0.
This gives 3db more power to chain1 in EIRP-Limited countries.

So you can switch polarisation to the polarisation which is connected
to chain1 but you cant avoid interference on polarisation which is
connected on chain0.
 
uldis
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Re: SXT Polarization

Mon Feb 21, 2011 12:53 pm

you can do like the user ste wrote, but you need to have antenna connected on RX chain0 so you could receive traffic on it.
 
ste
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Re: SXT Polarization

Thu Feb 24, 2011 4:35 pm

@uldis

Disabling tx on one chain on one side of the link limits the whole
link to 150MBit negotiation speed in *both* directions.

In a CPE/AP situation it might help to disable one chain of the
CPE to get better signal to the AP. CPE->AP signal is in most cases
the weaker signal.
 
wispwest
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Re: SXT Polarization

Tue Nov 29, 2011 2:55 am

I have a PtP setup, where I just upgraded one end to a 2' Parabolic Dish with RB/433 board. I have reversed chain's right now, and not seeing as good of data rates as I should.

I am going to correct the chains tomorrow, so that Chain0 is H and Chain1 is V. I will post my results if any improvement.

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