Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: Alfa RTL8187 Driver & Airodump

Hybrid View

  1. #1
    Junior Member
    Join Date
    Feb 2007
    Posts
    74

    Default Alfa RTL8187 Driver & Airodump

    I've noticed that in BT4 the new Alfa drivers cause airodump to report negative values under the "PWR" column. Also there's no "RXQ" column anymore. Not sure if these are bugs persay. I have noticed a substantial increase in the power of this usb adapter though.

  2. #2
    Member
    Join Date
    Dec 2007
    Location
    The Netherlands
    Posts
    267

    Default

    I assume it now shows the power in dBm, which is always a negative.

    My home AP gets -41dBm, whilst the neighbours AP yields -61dBm. This behaviour does make sense

  3. #3
    Just burned his ISO
    Join Date
    Sep 2008
    Posts
    18

    Default

    Yes, I noticed that to. But to be fair if still works a treat.

    Seemed to crack my wep just fine, not sure if its just me but seemed a bit quicker to!!

    Haven't had a chance to try anything else out yet tho!

    My little one thought it wolud be good to pour her juice in the telly so had a few sparks distracting my attention. Lol.

    Oh yea and fair play to muts and the gang for another outstanding backtrack compliation.

    Peace my fellow ethical hackers. Remember use your power for good!!

  4. #4
    Junior Member
    Join Date
    Feb 2007
    Posts
    74

    Default

    So if it is in dBm, the smaller the number the closer the AP?

  5. #5
    Just burned his ISO
    Join Date
    Sep 2008
    Posts
    18

    Default

    Look's like it. Think of it as a reverse scale -

  6. #6
    Junior Member
    Join Date
    Dec 2008
    Posts
    43

    Default

    I cant connect to wpa with this device from NetworkManager. How can i connect?

  7. #7
    Member
    Join Date
    Dec 2007
    Location
    The Netherlands
    Posts
    267

    Default

    Exactly, -41 is a stronger signal than -61. If memory serves the dBm scale is logarithmic, which means -41 is twice as strong as -42.

    But that might be my physics knowledge messing up.

    All in all: the negative numbers are not a bug, but a feature

  8. #8
    Member hawaii67's Avatar
    Join Date
    Feb 2006
    Posts
    318

    Default

    Quote Originally Posted by Citruspers View Post
    E If memory serves the dBm scale is logarithmic, which means -41 is twice as strong as -42.
    That's not correct. Doubling the power is equivalent to a 3dB increase in volume! So -40 dBm is double power that -43 dBm
    Don't eat yellow snow :rolleyes:

  9. #9
    Very good friend of the forum Virchanza's Avatar
    Join Date
    Jan 2010
    Posts
    863

    Default

    Don't be fooled by the negative sign, it doesn't result in a negative number, but rather a very small number. Here's how it works:

    -40 decibel milliwatts
    = -4 bel milliwatts
    = (10 to the power of -4) milliwatts
    = .0001 milliwatts
    = 100 nanowatts

    You can never get decibels to result in a negative number, never ever.

    Going the other way, if you wanted to convert the power of the Alfa to dBm, it'd be:

    500 milliwatts
    = 2.69897 bel milliwatts (I got this figure by taking the Log10 of 500)
    = 26.9897 decibel milliwatts
    So it's about 27 dBm
    Ask questions on the open forums, that way everybody benefits from the solution, and everybody can be corrected when they make mistakes. Don't send me private messages asking questions that should be asked on the open forums, I won't respond. I decline all "Friend Requests".

  10. #10
    Member
    Join Date
    Jun 2008
    Posts
    56

    Default

    the same "-"
    i see it with my Edimax -EW 7318usg

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •