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1240g Signal Flapping

Hello All,

We have a 1240g AP whose signal appears to be flapping.  It is strong one second and the next it is OFF.  We are not losing any pings to it and we have rebooted it and flashed it to the latest autonomous code, but still the signal keeps flapping.  See the attached screenshot from WiFi Analyzer.


Hall of Fame Super Blue

1240g Signal Flapping

1.  DO you have the correct antennas and the correct amount of antennas installed?

2.  Are you seeing this in 802.11a or 802.11b/g?

Community Member

1240g Signal Flapping


The association between the wireless client and the Access  Point (AP) can flap if there is Radio Frequency Interference (RFI) in  the channel (cell) used by the AP and the wireless client.


RFI  is the presence of unwanted interfering radio frequency signals from  different sources which disrupt the original data signal from the AP and  wireless clients. This results in intermittent connectivity issues  between the AP and the wireless client and in some cases can lead to  poor throughput, and low data rates.

You can use these methods to resolve this issue.

  • The  best solution to eliminate the RFI problem is to identify the source or  device which generates the unwanted RF signals and then remove that  source. This ensures that there is no other RF device operating in the  same cell (channel) as the WLAN devices. You can use a Spectrum Analyzer  to detect the presence of RF activity in a channel. You can also use  the Carrier Busy test option available on Cisco Aironet devices to test  for the presence of RF activity. For more information on the Carrier  Busy test, refer to Running the Carrier Busy Test

  • You  can also try to use a different channel for the WLAN communication. For  example, if unwanted RF signals disrupt one channel, (for example  channel 11), you can configure the wireless bridge or the AP to use  another channel, (for example channel 3), where there is no RFI.

  • Conduct  a site survey. A site survey is used to determine the best placement  and coverage (overlap) for your network's infrastructure devices. It is  always advisable to perform a site survey before implementing any WLAN  network to ensure high throughput and consistent performance. For more  information on a site survey, refer to Performing a Site Survey.
Community Member

1240g Signal Flapping

Thank you for the replies.  It still appears to be flapping, however connections are not being dropped.  I was able to stay connected all day and did a continual ping and nothing dropped.  I did move the channel to an area that was less congested and also switched the antenae. 

So again, thanks for all the input, it seems to be working!

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