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txpower for hostap driver

Regarding NL2511MP Prism based radios on Voyage and my two cents.

iwpriv wlan0 alc 0
iwpriv wlan0 writemif 62 128
iwpriv wlan0 readmif 62   #(CR31)
iwpriv wlan0 readmif 116 #(CR58)

# Setpower script for HostAP devices:

iwpriv wlan0 alc 0 > /dev/null 2>&1
iwpriv wlan0 writemif 62 %VALUE% > /dev/null 2>&1

/sbin/iwconfig wlan0 txpower xxxx

Does NOT work for setting values for txpower. You can only issue off or auto.

Seems you can lowlevel poke and peek values into the card for txpower on Prism still. The main problem is, they say the settings don’t stay forever. Everyone suggests putting in a cron every 5 minutes to reissue the commands.

If you want to see what is in the register 62 spot then you do:

/sbin/iwpriv wlan0 readmif 62

If you want to change that value you have to do:

/sbin/iwpriv wlan0 alc 0
/sbin/iwpriv wlan0 writemif 62 128

# Setpower script for HostAP devices, save as /root/Setpower

/sbin/iwpriv wlan0 alc 0 > /dev/null 2>&1
/sbin/iwpriv wlan0 writemif 62 128 > /dev/null 2>&1

Create a file called /root/crontab and put this in there:

  • /5 * * * * /root/Setpower

Then do:

crontab /root/crontab

Now you may want to put that into some autostart file as well.

The value of 128 put into register 62 is on some weird scale where 128 is the highest number and 127 is the lowest and the numbers 0 or 255 means 50%. Nobody can tell you what value to put into register 62 for a specific card to get a specific txpower out of it. The reason for this is a 200mW card will output something different than a 50mW card does when at 100% or even 50%.

You might try

/sbin/iwpriv wlan0 writemif 62 190

instead of 128 as 190 is evidently lowering the output a bit.

They do usually suggest output to be slightly less than max though for the card so that it is not over doing it. They liken it to a stereo that is turned up to it’s max and how it has distortion.

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