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Thread: Measured signal values degrade when connected to an AP

  1. #1

    Default Measured signal values degrade when connected to an AP

    Looking for some feekback on an issue I ran into:

    If I start up inSSIDer (v3) and measure signal strength on an AP (cisco 1140 in this case) I get a value of -55. However, if I then associate to that AP, the signal strength measurements become erratic... sometimes swaying so far as from -55 to -70.

    The problem seems to go beyond just the value that is being displayed in the application as well... I tested with a file transfers and even pings. If inSSIDer is running ping times go all over the place form 1ms to 300ms and transfer speeds fluctuate. As soon as I close the application everything clears up.

    I installed and tested with a similar wifi tool and measured the same -55 value while not associated and while associated... In other words, I do not see the erratic signal strength changes when I am associated to the AP. Ping and transfer speeds are not affected either.

    This was in a new environment... there were no other connections to the AP or even the entire network. I'm running inSSIDer v3 on Win8 Pro x64, wireless card is an Intel Centrino Advanced-N 6250 AGN

    Can anyone shed light on this? Expected/normal behavior?

  2. #2

    Default

    The varying ping times are normal. inSSIDer has to poll the wireless card quite while it is running, which keeps it tied up enough to heighten ping times. An interesting test would be to use inSSIDer with a USB wireless card, and perform your throughput tests with your internal wireless adapter to see if each card can work independently.

    As for the varying signal strength, do you have the same problem with other wireless adapters?
    Joel, Mobility+, ECSE, CWNE #233
    Technical Trainer
    MetaGeek

  3. #3

    Default

    Quote Originally Posted by aeccles View Post
    Looking for some feekback on an issue I ran into:

    If I start up inSSIDer (v3) and measure signal strength on an AP (cisco 1140 in this case) I get a value of -55. However, if I then associate to that AP, the signal strength measurements become erratic... sometimes swaying so far as from -55 to -70.

    The problem seems to go beyond just the value that is being displayed in the application as well... I tested with a file transfers and even pings. If inSSIDer is running ping times go all over the place form 1ms to 300ms and transfer speeds fluctuate. As soon as I close the application everything clears up.

    I installed and tested with a similar wifi tool and measured the same -55 value while not associated and while associated... In other words, I do not see the erratic signal strength changes when I am associated to the AP. Ping and transfer speeds are not affected either.

    This was in a new environment... there were no other connections to the AP or even the entire network. I'm running inSSIDer v3 on Win8 Pro x64, wireless card is an Intel Centrino Advanced-N 6250 AGN

    Can anyone shed
    led lights on this? Expected/normal behavior?
    hello friend were you able to sort out the problem? I am facing similar issue so please help me if you can..Waiting for reply thanks in advance
    Last edited by JasonPatrick; 07-22-2013 at 12:02 AM.

  4. #4

    Default

    aeccles

    When inSSider is working it must use your wf-fi card to scan all available wi-fi channels so that it can report back on the networks available on all channels. Your wi-fi connection will be momentarily disrupted while the wi-fi card goes off the channel you are using for your connection to your access point and briefly scans the remaining channels in the 2.4GHz range. This is why some times the ping is erratic.

    This can be proved by taking a wireshark capture. You will see your network card sending "Null Data" or "Null QoS Data" frame every so often. This is a frame that you wi-fi client adapter most often uses, to tell the AP which it is connected to, that it is going off channel or in to sleep mode and the AP should buffer any frames destined for it until it comes back on line.

    You will also see this kind of effect on your ping response time and throughput when you are using aggressive power saving mode. This time the client goes to sleep in order to save battery life. When it does so it notifies the AP of its sleep mode by sending the same null data frames. It will wake periodically to download any buffered frames.

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