How to tell the difference.....

I have written some documentation on wireless (not published on the web. It’s for my work. I don’t see why I couldn’t modify some of it and publish it online), but one thing I have not been able to get a solid answer on is, how to tell the difference between wireless interference and a bad card or driver.

On 06/03/2013 07:36 PM, Jonathan R wrote:
>
> I have written some documentation on wireless (not published on the web.
> It’s for my work. I don’t see why I couldn’t modify some of it and
> publish it online), but one thing I have not been able to get a solid
> answer on is, how to tell the difference between wireless interference
> and a bad card or driver.

I’m not sure if there is a definite answer other than putting the device and AP
in a radio-shielded room, or by connecting them with an attenuator cable. As
both of those are expensive, these techniques are not available to most of us.

A scan will show how much interference there is from other wifi radios, but it
does not show other sources such as leaky microwaves, etc. You can also set up a
radio spectrum analyzer and look for such background radiation or bursts that
correspond to connection loss.

On 06/04/2013 05:04 AM, Larry Finger wrote:
> putting the device and AP in a radio-shielded room … expensive

so, if i understand the OP’s quandary he seeks a way to help the
average user determine if encountered wireless problems (variable
transfer rates, drop outs, etc) are in the card/driver or local
interference…

all of Larry’s info is correct (of course) but the average user will
have neither a radio spectrum analyzer nor a radio shielded room, and
not even the lesser expensive method of using a small Faraday
cage…http://en.wikipedia.org/wiki/Faraday_cage

so, i don’t know how to help the average user know for sure the
source of the problem, but perhaps a description of common sources of
interference and techniques to minimize them (try at different times
of day [say when it is unlikely the neighbor is microwaving, etc];
moving AP and/or device to notice shifts in transfer speed/etc [rate
drop when both sit next to the window–when compared to rate when
both are in the sub-basement, or deep interior room]; other
techniques to discover/deal with interference–ask a ham…hmmm you
could start here
http://www.arrl.org/radio-frequency-interference-rfi but
the basics are gonna overwhelm most users)


dd

Thank you for the responces. So basically, there is no feasible way to tell the difference with out those tools. That helps me in writing up documentation. Thank you.

On 06/07/2013 12:26 AM, Jonathan R wrote:
> no feasible way to tell the difference

yes and no…you can’t quantify/measure and be certain if the
problems encountered are attributable to interference or hardware;
or attributable to interference and hardware…

at least you can’t be sure what is going on until you eliminate
interference as a possible cause of the problem (or a possible cause
of some of the problem)…

but, by varying the locations of the two ends (and/or time of day of
the operations) and observing how that affects the stability, speed,
and etc of the connection it may be possible to infer that
interference is playing a role, or not.

that is, without those tools it is determined that (for example)
everyday, Monday through Friday between 8 AM and 5 PM the max speed
available is far below what it is at midnight–then, one might infer
that both the driver and hardware probably remain the same throughout
the week and there must therefore be something else causing the
wireless problems…same if the AP and laptop with suspected
hardware or driver problems are both moved from their normal location
(where reception is poor/spotty) to inside the concrete bomb shelter
in the basement and it is noted that suddenly the wi-fi is rock
steady at max speed . . .


dd