I
completely agree. However, I think most WiFi radios don't report
S/N ratios so you have to draw the line somewhere without that
data. There maybe a way of interpreting the number of bad
packets received as a surrogate.
I Microsoft considers -100dBm to be 'no' signal and Linux
-110dBm. There probably is a noise floor that the radio has when
it is simply sitting in a laptop at the North Pole (thermal
noise, shot noise, Johnson noise, and always 1/f noise -- it is
a long while since I studied noise). Not to mention the E coli
in the human guts nearby but their little motors probably don't
radiate much at 2.4GHz.
On 11/9/19 1:45 PM, Bill Riemers wrote:
I will bite. How can a signal be too small to
be considered a no signal? You need a certain minimum to
receive data over the background noise. Anything smaller than
that you want to consider no signal.
I haven't given up in
the hope that NM will make a better WiFi AP selection.
From what you have told me, a "supplicant", requests the
NM to open a network connection. The NM manager then
selects something from the various WiFi APs or wired
connections. From what you have said so far, the NM
manager prioritizes potential
data bandwidth over signal strength. As a
consequence, a 5GHz signal at -100dBm wins out over a
-40dBm 2.4GHz signal, despite the fact that the 5GHz
signal one millionth
the power of the 2.4GHz signal.
So I began to research how much power -100dBm represents.
My first thought was to compare the power to an ant. Not a
good choice since an ant can put out 50mW, according to
some people. A more useful comparison turns out to be a
bacterial flagellar motor (E. coli has them, for example).
They crank out 10⁻¹² mW which is -120dBm. So for -100dBm
you need 100 E. coli.
So the point of this? -100dBm is way too small to be
considered no signal. The edge of an acceptable signal is
around the power output 100,000 E. coli.
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--
Bill
C Riemers, PhD,
CSM, CSD, SALESFORCE CPD I
Senior
Software Engineer
Red Hat
Canada Ltd
Enterprise
Sales + Services (ESSA)
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