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Old 09-21-2012, 02:03 PM   #1
osubuckeyes
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Howto adjust tx power of Atheros AR9285 wireless card


I have a Lenovo G575 laptop with an Atheros AR9285 wireless card. Booted as Windows 7, the card's tx power is 27 dBm; running Fedora 17 (Kernel 3.5.3-1.fc17.x86_64), it's 15 dBm. A Belkin F5D8053 USB adapter runs at 27 dBm in either Windows or Linux. Neither Windows nor Linux seems to allow me to adjust the power of the Atheros card. How can I get the Atheros card to run at 27 dBm?
 
Old 09-22-2012, 10:34 AM   #2
camorri
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I have that card in my netbook, so I did tried some things. The driver is ath9k for that card.
The maximum power I could set is 20dbm. I could reduce it, but not increase it over 20 dbm. I do not have windbloze, so I have no idea what the windoze driver can do. My netbook works fine anywhere I have used it, so 20 dbm on mine is fine. Any value above 20 dbm returns an error. So, my I believe that is the maximum setting for the current driver.

The command to change Tx power is ( as root ) 'iwconfig wlan0 txpower xxdbm' ( no quotes and xx is the new value ).

You might want to read through this bug for ath9k.

-->https://lists.linux-foundation.org/p...er/023416.html

Not sure if this applies to your system or not.
 
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Old 09-23-2012, 02:33 PM   #3
osubuckeyes
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Thanks, but this does not help:

# iwconfig wlan0 txpower 20
Error for wireless request "Set Tx Power" (8B26) :
SET failed on device wlan0 ; Invalid argument.

# iwconfig wlan0 txpower 20dbm
Error for wireless request "Set Tx Power" (8B26) :
SET failed on device wlan0 ; Invalid argument.

BTW, I get the same error messages when attempting to set it to 19. But if Windows 7 runs at 27 by default, why doesn't Linux run it at 27 by default? Both Window and Linux run my USB adapter at 27.

# iwconfig wlan0
wlan0 IEEE 802.11bgn ESSIDff/any
Mode:Managed Access Point: Not-Associated Tx-Power=14 dBm
Retry long limit:7 RTS thrff Fragment thrff
Encryption keyff
Power Managementn
 
Old 09-23-2012, 07:24 PM   #4
camorri
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Quote:
BTW, I get the same error messages when attempting to set it to 19. But if Windows 7 runs at 27 by default, why doesn't Linux run it at 27 by default? Both Window and Linux run my USB adapter at 27.
Its not linux, its the driver. You could try and install the latest version of ath9k ( stable ). Here is a link for the latest stable release. -->http://linuxwireless.org/en/users/Download/stable/

This is source code. You have to compile the binary, then modprobe the driver. I would recommend if you go this route, you remove the old driver from your system.

I have no ides if fedora has the correct tools installed to compile a driver. You will have to look into that.
 
Old 09-24-2012, 03:43 PM   #5
osubuckeyes
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Quote:
Originally Posted by camorri View Post
Its not linux, its the driver. You could try and install the latest version of ath9k ( stable ). Here is a link for the latest stable release. -->http://linuxwireless.org/en/users/Download/stable/

This is source code. You have to compile the binary, then modprobe the driver. I would recommend if you go this route, you remove the old driver from your system.

I have no ides if fedora has the correct tools installed to compile a driver. You will have to look into that.
I was unable to compile the binary. I compiled a few kernels about a decade ago, but I have stuck to rpm files since then, so it could be my lack of skills or it could be a lack of tools in Fedora. In any event, I have not succeeded. Given that I get 27 dbm in Windows 7, would it make any sense to try ndiswrapper?
 
Old 09-24-2012, 05:05 PM   #6
camorri
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Do you have problems connecting to some access points? If no, I would advise you to leave it alone.

Ndiswrapper does work with some cards, however, some features on some cards will not work. I would only use it if I had no working linux binary. Your choice.
 
Old 09-25-2012, 08:57 AM   #7
osubuckeyes
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Quote:
Originally Posted by camorri View Post
Do you have problems connecting to some access points? If no, I would advise you to leave it alone.

Ndiswrapper does work with some cards, however, some features on some cards will not work. I would only use it if I had no working linux binary. Your choice.
I have no problem connecting to access points if I am very close to them. It's just an inconvenience to have to use the USB adapter for most purposes.

Thanks for your help.
 
Old 03-06-2013, 11:25 PM   #8
pizzar0
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This may be necro... but if anyone still cares, one needs to set the reg(ulatory) domain to one that allows higher txpower settings. (example: 'OB' -> "iw reg set OB")
 
  


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