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Thread: Realtime Wi-Fi strength/noise-meter

  1. #1
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    Århus, DenmarK
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    Kubuntu 8.10 Intrepid Ibex

    Realtime Wi-Fi strength/noise-meter

    Hi there,

    I'm setting up a network between an apartment on the second floor, and an apartment on the ground floor. I didn't think this would cause any problems - but it does!

    Unfortunately I'm not able to use cables in this setup! And I can't mount the antennas outside, since I'm not allowed to mount anything on the outside of the building.

    I have set up 2 directional antennas pointing at each other (not perfectly, yet) - But the signal is horrible.

    Is there a tool in linux to measure the strength of a not yet connected network, in order to align the antennas?

    Thank you in advance!

  2. #2
    Join Date
    Oct 2006
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    513

    Re: Realtime Wi-Fi strength/noise-meter

    Not sure if this is the best solution, but this is what I used when I was hunting for open networks in my flat.
    Code:
    # general:
    sudo watch -n <delay between updates> iwlist <wireless interface> scan
    # on my system:
    sudo watch -n 1 iwlist wlan0 scan
    EDIT: Just found out: you can filter the result by essid like this:
    Code:
    iwlist scan wlan0 essid <essid>
    Last edited by olejorgen; November 18th, 2008 at 12:52 AM.
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  3. #3
    Join Date
    Aug 2005
    Location
    Århus, DenmarK
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    Kubuntu 8.10 Intrepid Ibex

    Re: Realtime Wi-Fi strength/noise-meter

    Wow, iwlist seems effective!

    It seems that iwlist doesn't respect the essid setting, though:

    Code:
    watch -n 1 'sudo iwlist wlan0 scan essid jazzen'
    Note that I had to write the device before 'scan' for some odd reason.

    That command outputs this: (among other)

    Code:
              Cell 02 - Address: 00:17:9A:58:DC:2F
                        ESSID:"Ropemaster"
                        Mode:Master
                        Channel:6
                        Frequency:2.437 GHz (Channel 6)
                        Quality=55/100  Signal level:-75 dBm  Noise level=-127 dBm
                        Encryption key:on
                        IE: WPA Version 1
                            Group Cipher : TKIP
                            Pairwise Ciphers (1) : TKIP
                            Authentication Suites (1) : PSK
                        Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
                                  9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s
                                  48 Mb/s; 54 Mb/s
                        Extra:tsf=00000018e4afd179
                        Extra: Last beacon: 1420ms ago
    And that essid has nothing to do with 'jazzen' - which is the essid I'm interested in.

    Any ideas?

    UPDATE:

    I fixed it ad-hoc, though it's not that nice:

    watch -n 1 'sudo iwlist wlan1 scan | grep -B 1 -A 15 "jazzen"'
    But the response is not that good:

    Quality=45/100 Signal level:-86 dBm
    I've moved the antenna 20 meters - still on the ground-floor, so that it's directly below the apartment, and it increased the quality dramatically, but I still can't connect:

    Quality=88/100 Signal level:-45 dBm Noise level=-127 dBm
    What is the Signal level and Noise level readings? - and what should I be aiming at?
    Last edited by daller; November 18th, 2008 at 03:45 PM.

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