Daniel Cohen
f2s.com> wrote:
> David Empson wrote:
>
>> To simplify the question: has she _ever_ successfully connected her
>> computer to a wireless network?
>>
>> The evidence so far suggests that her PowerBook's Airport hardware is
>> faulty in some way. It might be as simple as the antenna not being
>> plugged in (inside the computer).
>>
>> If her Airport has worked fine elsewhere (recently) then it may be an
>> environmental issue such as interference with your Airport network.
>
> Oh yes, it works most of the time. Fine in Eudora, mostly OK in Safari,
> just stops from time to time.
That didn't answer my question. Has her computer ever worked reliably on
other wireless networks, or has its Airport interface only ever been
used on your network, so you have no basis for comparison?
>> The numbers showing signal and noise both around -90 means that the base
>> station is getting almost no connection to that computer, due to
>> extremely low signal strength: the "signal" figure should be between -50
>> and -80, but "noise" is typically around -90 in my experience. The
>> "rate" of 5 (megabits per second) is also extremely low, probably the
>> best that can be achieved given the weak signal.
>>
>> This is very likely to be a problem with interference from an outside
>> source, or a fault with the Airport card or antenna in either your base
>> station or her laptop.
>
> I'm wondering if there's something weird about the statistics on my
> system, or whether it is a function of not actually using wireless at
> the time of writing. Because the connection between my main Airport base
> station (connected to my iMac by ethernet) and the remote base station
> (part of a WDS network) only shows a signal level of around -80 in both
> directions. And my Squeezebox shows signal -78 noise -1 rate -1 but
> works fine without the slightest problem.
That is a low but usable signal. -80 dBm signal with noise of -90 dBm
means that the signal has ten times more power than the background
noise.
If both signal and noise are around -90 dBm then the signal is almost
indistinguishable from the noise, and you are likely to get very slow
performance and dropouts.
(The -1 figures for noise and rate must be misreported by Airport
Utility - those numbers are impossible.)
> In fact it seems quite likely that the statistics are weird. I've
> downloaded a few other programs for checking wifi connections. AirMoose
> is showing signal -55, noise -87 at the same time that Airport Utility
> shows signal -81, noise -87. And another utility is showing much the
> same as AirMoose.
Don't forget that you are looking at the signals from opposite
directions. The Airport Utility stats are reporting the signal strengths
as seen by the Airport base station, which will depend on the transmit
power of the other device (e.g. the PowerBook G4 in question). Any
software you run on the computer indicates signal strength as seen by
the computer, which depends on the transmit power of your base station.
If those numbers you quoted for the PowerBook G4, it sounds like the
PBG4's transmission is weak but its reception may be OK. That could be
due to an antenna problem.
--
David Empson
dempson@actrix.gen.nz
