[Trac #852] iwconfig signal and noise level -2 dBm returned on first use

[Zarro Boogs per Child]

#852: iwconfig signal and noise level -2 dBm returned on first use
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 Reporter:  Quozl     |        Owner:  marcelo 
     Type:  defect    |       Status:  assigned
 Priority:  high      |    Milestone:  BTest-3 
Component:  wireless  |   Resolution:          
 Keywords:            |  
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Comment (by rchokshi):

 Replying to [comment:4 marcelo]:
 > Ronak,
 >
 > This is a firmware/hardware problem. GET_RSSI command returns, in
 certain situations (100% certain just after association happened), a value
 of "2" for absolute noise floor, while absolute SNR correctly contains
 "0".
 >
 > As Quozl mentions, repeated use gives realistic values.
 >
 > The following situation is common:
 >
 > {{{
 > GET_RSSI, absNF = 2
 > GET_RSSI, absNF = 2
 > GET_RSSI, absNF = realistic value
 > GET_RSSI, absNF = 2
 > GET_RSSI, absNF = realistic value
 > GET_RSSI, absNF = realistic value
 > ...
 > }}}
 >
 > Why would the firmware/hardware return noise floor = 2? Its smells like
 a default of some sort in the sensing logic?
 >

 this is expected for the initial set of GET_RSSI, GET_NF reading as you
 reported. This is the time when the STA has just gained association with
 the AP or another mesh network and the baseband gets brand new values of
 RSSI and NF. And the initial values can be everywhere. But this should
 level out over time because of the continuous averaging in the firmware.

-- 
Ticket URL: <http://dev.laptop.org/ticket/852#comment:5>
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