* AR9280 reported signal strengths are flat (comparison with bcm4322 included) @ 2012-05-15 15:04 George Nychis 2012-05-16 6:08 ` Holger Schurig 0 siblings, 1 reply; 6+ messages in thread From: George Nychis @ 2012-05-15 15:04 UTC (permalink / raw) To: linux-wireless I am experiencing unexpected signal strength values reported by an AR9280. Basically, they always tend to be flat no matter how far or close I am from the device that is transmitting. Roughly between the -65 and -55dBm range on average. The exact AR9280 I am using is: Sony UWA-BR100 802.11abgn Wireless Adapter [Atheros AR7010+AR9280] I have compared this behavior to a bcm4322 and the behavior I see with the bcm4322 is as expected. Far away I get low signal strength values, and close to the device I get high signal strength values (-20dBm). Here is a comparison of the two (taken at the same time) as I walk closer to the transmitter. I record the signal strength from wireshark using radiotap header field radiotap.dbm_antsignal. http://www.flickr.com/photos/gnychis/7203437510/in/photostream Surprisingly, the average signal strength seems to decrease with the ar9280 as I get closer, yet remains relatively flat. The bcm4322 shows a clear increasing trend as I get closer. Does anyone have any insight as to what might be going on? I'm using the most recent firmware and compat-wireless as of May 14, 2012. Thanks! George ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: AR9280 reported signal strengths are flat (comparison with bcm4322 included) 2012-05-15 15:04 AR9280 reported signal strengths are flat (comparison with bcm4322 included) George Nychis @ 2012-05-16 6:08 ` Holger Schurig [not found] ` <CA+7oygftxidR_r-t16K1g9CNPhL+EkMdPyKftkWoSk+Fzf+Rog@mail.gmail.com> 0 siblings, 1 reply; 6+ messages in thread From: Holger Schurig @ 2012-05-16 6:08 UTC (permalink / raw) To: George Nychis; +Cc: linux-wireless This is probably due to ANI (adapative noise immunity). I think ath9k does too much here, in other words: it doesn't just kick in if there are too strong signals there. Instead it seems to always adjust the input attenuator, needed or not. ^ permalink raw reply [flat|nested] 6+ messages in thread
[parent not found: <CA+7oygftxidR_r-t16K1g9CNPhL+EkMdPyKftkWoSk+Fzf+Rog@mail.gmail.com>]
* Re: AR9280 reported signal strengths are flat (comparison with bcm4322 included) [not found] ` <CA+7oygftxidR_r-t16K1g9CNPhL+EkMdPyKftkWoSk+Fzf+Rog@mail.gmail.com> @ 2012-05-16 18:32 ` George Nychis 2012-05-16 18:35 ` George Nychis 0 siblings, 1 reply; 6+ messages in thread From: George Nychis @ 2012-05-16 18:32 UTC (permalink / raw) To: Holger Schurig; +Cc: linux-wireless Hi Holger, Thanks a bunch for your response! I had read about ANI before on the list, it would be interesting to know if this is the cause for this. It definitely seems plausible. I will dig around the ath9k code and see if I can narrow down this to the cause. On Wed, May 16, 2012 at 2:31 PM, George Nychis <gnychis@gmail.com> wrote: > > Hi Holger, > > Thanks a bunch for your response! I had read about ANI before on the > list, it would be interesting to know if this is the cause for this. It > definitely seems plausible. I will dig around the ath9k code and see if I > can narrow down this to the cause. > > - George > > > On Wed, May 16, 2012 at 2:08 AM, Holger Schurig > <holgerschurig@googlemail.com> wrote: >> >> This is probably due to ANI (adapative noise immunity). I think ath9k >> does too much here, in other words: it doesn't just kick in if there >> are too strong signals there. Instead it seems to always adjust the >> input attenuator, needed or not. > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: AR9280 reported signal strengths are flat (comparison with bcm4322 included) 2012-05-16 18:32 ` George Nychis @ 2012-05-16 18:35 ` George Nychis 2012-05-17 3:36 ` George Nychis 0 siblings, 1 reply; 6+ messages in thread From: George Nychis @ 2012-05-16 18:35 UTC (permalink / raw) To: Holger Schurig; +Cc: linux-wireless BTW- is ANI _not_ applied on broadcast traffic? I notice that monitoring the signal strength of beacons does not show this behavior. Maybe not applied for localization reasons? - George On Wed, May 16, 2012 at 2:32 PM, George Nychis <gnychis@gmail.com> wrote: > Hi Holger, > > Thanks a bunch for your response! I had read about ANI before on the > list, it would be interesting to know if this is the cause for this. > It definitely seems plausible. I will dig around the ath9k code and > see if I can narrow down this to the cause. > > > On Wed, May 16, 2012 at 2:31 PM, George Nychis <gnychis@gmail.com> wrote: >> >> Hi Holger, >> >> Thanks a bunch for your response! I had read about ANI before on the >> list, it would be interesting to know if this is the cause for this. It >> definitely seems plausible. I will dig around the ath9k code and see if I >> can narrow down this to the cause. >> >> - George >> >> >> On Wed, May 16, 2012 at 2:08 AM, Holger Schurig >> <holgerschurig@googlemail.com> wrote: >>> >>> This is probably due to ANI (adapative noise immunity). I think ath9k >>> does too much here, in other words: it doesn't just kick in if there >>> are too strong signals there. Instead it seems to always adjust the >>> input attenuator, needed or not. >> >> ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: AR9280 reported signal strengths are flat (comparison with bcm4322 included) 2012-05-16 18:35 ` George Nychis @ 2012-05-17 3:36 ` George Nychis 2012-05-23 18:36 ` George Nychis 0 siblings, 1 reply; 6+ messages in thread From: George Nychis @ 2012-05-17 3:36 UTC (permalink / raw) To: Holger Schurig; +Cc: linux-wireless Well, I believe that I forced ANI to be disabled and I still see this same behavior. To disable ANI on my AR9280, I added this to __ath9k_hw_init() in hw.c if (AR_SREV_9280(ah)) ah->config.enable_ani = false; I believe this works because in ath9k_hw_post_init() I have checked that ah->config.enable_ani is set to false. Therefore, ath9k_hw_ani_setup() and ath9k_hw_ani_init() are never called. Unfortunately, I still see this same flat line trend without strong signal strengths near the device. On Wed, May 16, 2012 at 2:35 PM, George Nychis <gnychis@gmail.com> wrote: > > BTW- is ANI _not_ applied on broadcast traffic? I notice that > monitoring the signal strength of beacons does not show this behavior. > Maybe not applied for localization reasons? > > - George > > > On Wed, May 16, 2012 at 2:32 PM, George Nychis <gnychis@gmail.com> wrote: > > Hi Holger, > > > > Thanks a bunch for your response! I had read about ANI before on the > > list, it would be interesting to know if this is the cause for this. > > It definitely seems plausible. I will dig around the ath9k code and > > see if I can narrow down this to the cause. > > > > > > On Wed, May 16, 2012 at 2:31 PM, George Nychis <gnychis@gmail.com> wrote: > >> > >> Hi Holger, > >> > >> Thanks a bunch for your response! I had read about ANI before on the > >> list, it would be interesting to know if this is the cause for this. It > >> definitely seems plausible. I will dig around the ath9k code and see if I > >> can narrow down this to the cause. > >> > >> - George > >> > >> > >> On Wed, May 16, 2012 at 2:08 AM, Holger Schurig > >> <holgerschurig@googlemail.com> wrote: > >>> > >>> This is probably due to ANI (adapative noise immunity). I think ath9k > >>> does too much here, in other words: it doesn't just kick in if there > >>> are too strong signals there. Instead it seems to always adjust the > >>> input attenuator, needed or not. > >> > >> ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: AR9280 reported signal strengths are flat (comparison with bcm4322 included) 2012-05-17 3:36 ` George Nychis @ 2012-05-23 18:36 ` George Nychis 0 siblings, 0 replies; 6+ messages in thread From: George Nychis @ 2012-05-23 18:36 UTC (permalink / raw) To: Holger Schurig; +Cc: linux-wireless Might anyone else have some insight here? I've tried digging through the code to see if AGC is not properly taken in to consideration during the RSSI calculation, but I think this is done in the firmware which is out of view of my eyes. On Wed, May 16, 2012 at 11:36 PM, George Nychis <gnychis@gmail.com> wrote: > > Well, I believe that I forced ANI to be disabled and I still see this > same behavior. > > To disable ANI on my AR9280, I added this to __ath9k_hw_init() in hw.c > if (AR_SREV_9280(ah)) > ah->config.enable_ani = false; > > I believe this works because in ath9k_hw_post_init() I have checked > that ah->config.enable_ani is set to false. Therefore, > ath9k_hw_ani_setup() and ath9k_hw_ani_init() are never called. > > Unfortunately, I still see this same flat line trend without strong > signal strengths near the device. > > > On Wed, May 16, 2012 at 2:35 PM, George Nychis <gnychis@gmail.com> wrote: > > > > BTW- is ANI _not_ applied on broadcast traffic? I notice that > > monitoring the signal strength of beacons does not show this behavior. > > Maybe not applied for localization reasons? > > > > - George > > > > > > On Wed, May 16, 2012 at 2:32 PM, George Nychis <gnychis@gmail.com> > > wrote: > > > Hi Holger, > > > > > > Thanks a bunch for your response! I had read about ANI before on the > > > list, it would be interesting to know if this is the cause for this. > > > It definitely seems plausible. I will dig around the ath9k code and > > > see if I can narrow down this to the cause. > > > > > > > > > On Wed, May 16, 2012 at 2:31 PM, George Nychis <gnychis@gmail.com> > > > wrote: > > >> > > >> Hi Holger, > > >> > > >> Thanks a bunch for your response! I had read about ANI before on the > > >> list, it would be interesting to know if this is the cause for this. > > >> It > > >> definitely seems plausible. I will dig around the ath9k code and see > > >> if I > > >> can narrow down this to the cause. > > >> > > >> - George > > >> > > >> > > >> On Wed, May 16, 2012 at 2:08 AM, Holger Schurig > > >> <holgerschurig@googlemail.com> wrote: > > >>> > > >>> This is probably due to ANI (adapative noise immunity). I think > > >>> ath9k > > >>> does too much here, in other words: it doesn't just kick in if there > > >>> are too strong signals there. Instead it seems to always adjust the > > >>> input attenuator, needed or not. > > >> > > >> ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2012-05-23 18:36 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-05-15 15:04 AR9280 reported signal strengths are flat (comparison with bcm4322 included) George Nychis 2012-05-16 6:08 ` Holger Schurig [not found] ` <CA+7oygftxidR_r-t16K1g9CNPhL+EkMdPyKftkWoSk+Fzf+Rog@mail.gmail.com> 2012-05-16 18:32 ` George Nychis 2012-05-16 18:35 ` George Nychis 2012-05-17 3:36 ` George Nychis 2012-05-23 18:36 ` George Nychis
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