Unable to set txpower on wifi card

JB jb.1234abcd at gmail.com
Mon Aug 30 21:22:36 UTC 2010


JD <jd1008 <at> gmail.com> writes:

> 
>   F13, latest updates.
> wifi card: Sparklan wmir-200N
> http://www.sparklan.com/product.php?func=view&prod_id=43
> Chipset: RT2860/RT2850
> 
> The Datasheet says:
> 
> Output Power
> 802.11a: 12.5dBm ± 1.5dBm
> 802.11b: 17dBm ± 1.5dBm
> 802.11g: 14dBm ± 1.5dBm
> 802.11an: 14dBm ± 1.5dBm
> 802.11gn: 14dBm ± 1.5dBm
> 
> I am running in g mode (54megabits/s)
> 
> $ sudo iwconfig wlan0
> wlan0     IEEE 802.11abgn  ESSID:"Deleted"
>            Mode:Managed  Frequency:2.462 GHz  Access Point: 
> aa:bb:cc:dd:ee:ff
>            Bit Rate=54 Mb/s   Tx-Power=8 dBm <<<=====
>            Retry  long limit:7   RTS thr:off   Fragment thr:off
>            Encryption key:off
>            Power Management:on
>            Link Quality=70/70  Signal level=58 dBm
>            Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
>            Tx excessive retries:0  Invalid misc:0   Missed beacon:0
> 
> I tried to set txpower to 14 per datasheet spec:
> 
> $ sudo iwconfig wlan0 txpower 14dBm
> Error for wireless request "Set Tx Power" (8B26) :
>      SET failed on device wlan0 ; Invalid argument.
> 
> The drivers that are loaded for this wifi card are:
> 
> rt2800pci               7931  0
> rt2800lib              27818  1 rt2800pci
> rt2x00pci               5799  1 rt2800pci
> rt2x00lib              25936  3 rt2800pci,rt2800lib,rt2x00pci
> mac80211              182154  2 rt2x00pci,rt2x00lib
> cfg80211              135626  2 rt2x00lib,mac80211
> eeprom_93cx6            1305  1 rt2800pci
> crc_ccitt               1311  2 rt2800pci,irda
> 
> Is this an issue with the wext driver or with the rt2XXXXX drivers?
> 
Hi,
$ man iwconfig
...
      txpower
              ...
              In  addition,  on and off enable and disable the radio, and auto
              and fixed enable and disable power control  (if  those  features
              are available).
              ...
                  iwconfig eth0 txpower auto

$ sudo iwconfig wlan0
...
           Bit Rate=54 Mb/s   Tx-Power=8 dBm <<<=====
...

The Tx-Power=8 dBm
means "fixed" power control (as opposite to "auto").
JB




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