[ath5k-devel] ath5k power drops in the presence of interference

2011-03-17 Thread Alex

Hi,

the last few days i've been experimenting with ath5k and its behaviour 
under interference (through a jammer in a neighbour channel).


I used a sender and a reveiver in IEEE 802.11a and in adhoc mode. I 
collected SNR measurements in the receiver node. Whenever jammer was on, 
SNR dropped at the receiver.


I then used airmagnet to monitor the signal strength of the sender.

Suprisingly i noticed that the tranmission power of the sender drops 
frequently when jammer was on; therefore SNR at the receiver dropped 
because the signal of the sender dropped and not because

noise was increased.

Then i connected the sender and the receiver through an airlive AP. I 
monitored the SNR at the receiver, capturing airlive's packets only. No 
SNR drops when jammer was on.


So i conlcude:

1) Ath5k's transmission power for some reason drops when interference is 
present.


2) SNR does not drop in the presence of interference (when an AP with a 
stable transmission power is used), meaning that the noise measured does 
not include interference.


Any comments are welcome.

Alex
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Re: [ath5k-devel] ath5k power drops in the presence of interference

2011-03-17 Thread Adrian Chadd
Does it do the same in 11bg mode?

Does madwifi behave the same way?

Don't forget to include the MAC/radio chipset and revision details; those
who know how the radios work will likely need that.


Adrian

On 17 March 2011 16:45, Alex alfr...@gmail.com wrote:

  Hi,

 the last few days i've been experimenting with ath5k and its behaviour
 under interference (through a jammer in a neighbour channel).

 I used a sender and a reveiver in IEEE 802.11a and in adhoc mode. I
 collected SNR measurements in the receiver node. Whenever jammer was on, SNR
 dropped at the receiver.

 I then used airmagnet to monitor the signal strength of the sender.

 Suprisingly i noticed that the tranmission power of the sender drops
 frequently when jammer was on; therefore SNR at the receiver dropped because
 the signal of the sender dropped and not because
 noise was increased.

 Then i connected the sender and the receiver through an airlive AP. I
 monitored the SNR at the receiver, capturing airlive's packets only. No SNR
 drops when jammer was on.

 So i conlcude:

 1) Ath5k's transmission power for some reason drops when interference is
 present.

 2) SNR does not drop in the presence of interference (when an AP with a
 stable transmission power is used), meaning that the noise measured does not
 include interference.

 Any comments are welcome.

 Alex

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 ath5k-devel@lists.ath5k.org
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