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Thread: Alfa awus036nh weak tx power. Is their a way to adjust?

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  1. #1
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    Default Alfa awus036nh weak tx power. Is their a way to adjust?

    I am running the rt2800 driver with the Alfa awus036nh wifi adapter. Injection and monitoring work great.However, my range is limited to less than that of my stock internal wireless card and iwconfig shows that it's txpower = 6dBm which seems very low.

    I have tried several methods to adjust, but most have been for other drivers...
    Is adjustment of txpower supported in rt2800?

  2. #2
    Super Moderator Archangel-Amael's Avatar
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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    The following two command should be looked at.
    # man iwpriv
    # man iwconfig

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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    Something like this happened with me, but my case is worst..

    My alfa adapter doesnt have tx power anymore. It just connects when below 1 meter range from my AP!! It happens in BT or windows, it seems like a hardware issue.

    I dont know what happened, but all of a sudden my adapter become very weak in it tx signal.

    The Rx signal is great, and works very well, but it is useless to try connect from more than 1 meter range..

    Do u know what is it?

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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    wow ...Alfa awus036nh works???...actually i heard that it is not supported by BACKTRACK out of box...can u tell me how did u made it work?,,plz

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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    I have tried iwpriv and the iwconfig methods of setting txpower.It seem that they are not supported with the rt2800usb driver. However, I performed a few informal tests against the built-in wireless adapter and it appears that the Alfa is stronger in Tx and Rx. This is in spite of the fact that iwconfig returns a value of 6dBm for the Alfa and 20dBm for the built-in atheros based adapter.

    I tried a few methods found on the net to get the awus036nh working without tradeoffs and found this the other day (near end of page):
    Please Help! With AWUS036NH RT2800 Driver Under uNetBootin USB BackTrack 4f

    I is a precompiled kernel image and header by Jusic at the german wardriving forums. Injection and Monitoring work great and the added bonus is that you can also surf the net with the rt2800usb driver. It updates the kernel to 2.6.33

  6. #6
    Just burned his ISO Net2010's Avatar
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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    i get today my new AWUS036NH after testing i see is Tx-Power=6 dBm is normal? plz any help

    PHP Code:
    root@bt:~# iwconfig
    lo        no wireless extensions.

    eth0      no wireless extensions.

    wlan0     IEEE 802.11bgn  Mode:Managed  Access PointNot-Associated
              Tx
    -Power=6 dBm
              Retry  long limit
    :7   RTS thr:off   Fragment thr:off
              Encryption key
    :off
              Power Management
    :on

    mon0      IEEE 802.11bgn  Mode
    :Monitor  Tx-Power=6 dBm
              Retry  long limit
    :7   RTS thr:off   Fragment thr:off
              Power Management
    :off 

  7. #7
    Super Moderator Archangel-Amael's Avatar
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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    Well what did your research tell you?
    To be successful here you should read all of the following.
    ForumRules
    ForumFAQ
    If you are new to Back|Track
    Back|Track Wiki
    Failure to do so will probably get your threads deleted or worse.

  8. #8
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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    Quote Originally Posted by D.B. Cooper View Post
    I have tried iwpriv and the iwconfig methods of setting txpower.It seem that they are not supported with the rt2800usb driver. However, I performed a few informal tests against the built-in wireless adapter and it appears that the Alfa is stronger in Tx and Rx. This is in spite of the fact that iwconfig returns a value of 6dBm for the Alfa and 20dBm for the built-in atheros based adapter.

    I tried a few methods found on the net to get the awus036nh working without tradeoffs and found this the other day (near end of page):
    Please Help! With AWUS036NH RT2800 Driver Under uNetBootin USB BackTrack 4f

    I is a precompiled kernel image and header by Jusic at the german wardriving forums. Injection and Monitoring work great and the added bonus is that you can also surf the net with the rt2800usb driver. It updates the kernel to 2.6.33
    Did you manage to increase the TX value?

    Im using the 2800usb drivers and trying to set highpower using iwpriv and tried changing the txvalue using iwconfig and both failed. The first with no private ioctls error and the second invalid argument error.

    I also tried the steps on this page, changing the 18187 to 2800 but that didnt work either.
    Tutorial: Improve TX power by changing the CRDA Regulatory Domain on Ubuntu

    I thought BT4 R2 would have worked with the NH card out of the box but that isnt the case.
    Packet Injection works with the 2800usb driver though.

    How much 'range' is lost by having tx value 4-8 rather than 30?

    Another point is using iwpriv channel or frequency only g channels are displayed. No N channels are displayed, this is still the case after changing the reg set value to different countries.

    Is this just a limitation of the 2800 driver?

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    Just burned his ISO RaderCad's Avatar
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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    Quote Originally Posted by spiers View Post

    How much 'range' is lost by having tx value 4-8 rather than 30?

    ?
    Now we are getting into RADIO theory realm.

    In my research (years) I have found a simple rule of thumb for the 2.4 to 2.5 gHz (microwave) bandwidth. As a starting point, 27 dBi (at the antenna) will get you out to 450 meters at 11Mb/s guaranteed (clear air no obstructions.) For every 3dBi added to that you get an effective doubling of the range. For every 3 dBi subtracted you get 1/2 the range. It is exponential, getting extra power is also exponential in the $ compartment. Being that this is the microwave band width the radiation danger with power boosting is also exponential.

    Now remember your antenna is 5 dBi or better added to 6 from the adapter you are now up to 11dBi. 27 - 11 = 16. 16 / 3 = 5.33 halvings or in 'range terms' something around 14 to 20 meters (clear air no obstructions.) Actual range varies due to atmospheric pressure and humidity but you get the picture (you are really limited.) Depending on the receiving sensitivity of the hot spot or hub, you can be further away.

    Note: The advertised ratings or watts from the ALFA's is not what you get. Search for the FCC reviews of all the ALFA's real power output without the antenna.

  10. #10
    Member skinnypuppy's Avatar
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    Default Re: Alfa awus036nh weak tx power. Is their a way to adjust?

    Just install the latest compat-wireless (http://wireless.kernel.org/download/...-01-17.tar.bz2)

    Follow the guide on the Aircrack-ng forum (http://forum.aircrack-ng.org/index.php?topic=5755.0)
    or this one (http://aircrack-ng.org/doku.php?id=compat-wireless)
    or the one in the forum by muts (http://www.backtrack-linux.org/forum...ight=awus036nh)

    My Alfa Awus036NH on the STOCK BT 4r2 Kernel:


    Code:
    root@bt:~# uname -r
    2.6.35.8
    
    root@bt:~# airmon-ng
    
    
    Interface       Chipset         Driver
    
    wlan0           Ralink RT2870/3070      rt2800usb - [phy1]
    wlan1           Atheros         ath5k - [phy0]
    
    root@bt:~# iwconfig
    lo        no wireless extensions.
    
    eth0      no wireless extensions.
    
    wlan0     IEEE 802.11bgn  ESSID:off/any
              Mode:Managed  Frequency:2.412 GHz  Access Point: Not-Associated
              Tx-Power=20 dBm
              Retry  long limit:7   RTS thr:off   Fragment thr:off
              Encryption key:off
              Power Management:on
    Results of iw list:

    Code:
    Wiphy phy1
            Band 1:
                    Capabilities: 0x172
                            HT20/HT40
                            Static SM Power Save
                            RX Greenfield
                            RX HT20 SGI
                            RX HT40 SGI
                            RX STBC 1-stream
                            Max AMSDU length: 3839 bytes
                            No DSSS/CCK HT40
                    Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                    Minimum RX AMPDU time spacing: 2 usec (0x04)
                    HT RX MCS rate indexes supported: 0-7, 32
                    TX unequal modulation not supported
                    HT TX Max spatial streams: 1
                    HT TX MCS rate indexes supported may differ
                    Frequencies:
                            * 2412 MHz [1] (20.0 dBm)
                            * 2417 MHz [2] (20.0 dBm)
                            * 2422 MHz [3] (20.0 dBm)
                            * 2427 MHz [4] (20.0 dBm)
                            * 2432 MHz [5] (20.0 dBm)
                            * 2437 MHz [6] (20.0 dBm)
                            * 2442 MHz [7] (20.0 dBm)
                            * 2447 MHz [8] (20.0 dBm)
                            * 2452 MHz [9] (20.0 dBm)
                            * 2457 MHz [10] (20.0 dBm)
                            * 2462 MHz [11] (20.0 dBm)
                            * 2467 MHz [12] (20.0 dBm) (passive scanning, no IBSS)
                            * 2472 MHz [13] (20.0 dBm) (passive scanning, no IBSS)
                            * 2484 MHz [14] (20.0 dBm) (passive scanning, no IBSS)]
    I have NO idea where all of this iw reg set BO stuff is coming from to change the power on the 36NH (maybe the 36) but would love to see it because as long as I've had these cards and as many variants of *nix as I run (Gentoo, Slackware) I have never had that command do anything whatsoever.
    Last edited by skinnypuppy; 01-19-2011 at 01:10 PM.
    I may have been born with a silver spoon in my mouth but it does not mean I like to be spoon fed.

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