31-08-2007, 15:35 #1
Bem não sei se o lugar desse topico seria aqui mesmo, mas vamos la.
Eu tenho um PC funcionando como Access Point com dois cartões modelo NMP-8602 PLUS (ETSI), quando dou iwlist ath0 txpower obtenho o seguinte:
ath0 8 available transmit-powers :
0 dBm (1 mW)
6 dBm (3 mW)
8 dBm (6 mW)
10 dBm (10 mW)
12 dBm (15 mW)
14 dBm (25 mW)
16 dBm (39 mW)
18 dBm (63 mW)
Current Tx-Power=18 dBm (63 mW)
Bem, porem onde eu comprei os cartões eles falaram que esse cartão é de 400Mw, como eu faria pra aumentar a potencia do desses cartões?
Quando tento com o iwconfig, acontece o seguinte:
meupc:/# iwconfig ath0 txpower 20
Error for wireless request "Set Tx Power" (8B26) :
SET failed on device eth2 ; Invalid argument.
Obs O adaptador de Minipci/PCI que uso tem dois jumpers, um falando 3.3V e outro 5V(ou algo assim), por padrão ja veio os dois jumpers fechados(ligados), sera que pode ser algo nesses adaptadores que pode não estar deixando com que os cartões trabalhem numa potencia mais alta? ou sera que o driver madwifi tem que ter alguma alteração na hora de instalar para que os cartões trabalhem com mais txpower?
Valeu pessoal, qualquer ajuda eu agradeço xD
02-09-2007, 00:33 #2
= Using Ubiquiti 400mW cards with Madwifi =
I had some trouble getting an SR-2 card to work with Madwifi and had to have it exchanged. Here's my experience, in case it helps others. Ubiquiti Networks provided really great customer service in the process!
== Original request for help, sent Oct 7th 2005 ==
I purchased an SR-2 (SR2_REV002) in June from wisp-router.com and I have never been happy with it. Last week-end I was finally able to do a 1-1 comparison to a 80mW Wistron CM-9 and a 80mW Senao NL-5354 Aries2 and the SR-2 provides noticeably worse connections.
My set-up is a WRAP.2C x86 single board computer running Linux and using the MadWifi driver (I tried both a 6-month old version and the latest version). I am using a U.fl pigtail and a 15dBi Pac Wireless Vagi, and I'm swapping the radios in&out. The other end is 9 miles away with also a WRAP board, a CM-9 radio, and a 18dBi grid.
The SNR (as measured by the driver) at the far end is around 10-14dB, which I realize is marginal, but does allow connections at between 1Mbps and 11Mbps data rates. The SNR for all 3 radios is essentially the same, i.e., I don't see any systematic 7dB signal improvement at the far end. I do see about a 2x better throughput (measured using ttcp) when using the CM-9 or the Senao over the SR-2! I also see higher packet loss rates when using the SR-2.
I have used the SR-2 in other settings where I also swapped it against a CM-9 and it always performed worse (but in those situations it was harder to exclude experimental errors because my measurement tools weren't as well controlled). I never saw an improvement in any of my experiments when using the SR-2 over a CM-9.
I would really like to switch a number of my long distance links (see http://www.diablo.sbarc.org) to the SR-2 and SR-5, but given the performance of the card I have that doesn't sound like a good idea. Do I perhaps have a bad card? (I have tried a MMCX pigtail and saw no difference.) What can you recommend?
== Ubiquiti's response ==
We received your card today and did some testing against CM-9 in our labs. We see a very clear 8dB link gain improvement. There is also a throughput advantage.
So, I don't know what is going on.
However, we have made some improvement to make our EEPROM programming more robust a while back and this seems to have helped some of the MADWIFI users.
Let me get you a couple new cards out and let's see what happens.
It is also possible your system setup might be a contributor. What SBC are you using? How about your power injector -- is it sufficient?
== The end result: success! (Oct 29th) ==
I was finally able to test the returned cards. Many thanks for the extra card: that is immensely appreciated! In short, everything now works beautifully! It seems the EEPROM changes made all the difference. Over short distances it's hard to see the tx power improvement, but over a 9 mile link the approx 8dB are clearly there!
I have one station powered by a 12v supply through over 100ft of cat-5, and that doesn't work: the whole WRAP board resets if I do heavy transmit tests, but that's not too surprising. With a good 12v supply everything looks fine.
That was really excellent customer service! I hope their business is going well and wish them the best of luck!
== A different response from wisp-router.com ==
Recommendations is to use only 1 SR card in a WRAP board and to use at least
18V if you are doing POE and even if you're not. 15W capable PSU is for most
part enough with one radio card even when doing POE.
Also in the past we have noticed strange behavior with some cards on the
WRAP.2C boards especially if you're using the mini-pci slot on the back of the
board but mainly in conjuction with a card in the front slot. It seems that
the front slot gets all priority and the back/bottom slot only gets
== Power setting for Ubiquiti SR2 ==
Apparently what Ubiquiti does in the firmware is to program slightly fudged
power settings. The actual output power corresponds to the output setting
issued by iwconfig + 10db. So the 16dbm setting is actually the 26dbm (400mW)
Tx output power, and setting 6dbm would actually yield 16dbm output power, etc.
See [wiki:Compatibility/Ubiquiti] for more information about the TX power offsets.
== New wrap2c since december 2005 ==
The new boards got better onboard hardware to use 400mw cards in both slots.
- Steffen D. meshnode.org
02-09-2007, 18:30 #3
No madwifi eu não consegui ainda. Mas não confunda qualidade de sinal com potencia. 18 dbm é o suficiente para 7 km usando antenas de boa qualidade.
Exemplo 18 dbm + 14 dbi ( painel ), 6 km ficou show de bola. Se precisar mais mude a antena. 17, 20 etc.
Cara é foda ter ingles limitado, mas deu pra entender o post do amigo.
Mas minha opnião, use a d-link 530, ela seta em 18 dbm e fica muito bom.
Agora com mikrotik da pra elevelar a potencia.