On 7 Sep 2011 21:52:58 GMT, "tommy alimo" <firstname.lastname@example.org>
>but if I don't get that symptom with the pings, then there can be no
>(significant) interference problem?
Variable latency is just one of the symptoms of interference. It's
like a runny nose and a cold. If you have a cold, it's highly likely
that you have a runny nose. However, if you have a runny nose, it can
be caused by a cold, flu, hay fever, allergy, etc. It really depends
on the source of the interference. For example, a periodic
interference source will usually produce very consistent latency
figures. Instead of the usual 1-2 msec latency, you'll see a much
larger number, with little variation.
Because the ping packets are small, they don't test for all forms of
interference. A much better indication is a thruput test. I suggest
you download and use Jperf:
If you get nice stable upload and download speeds through the wireless
link, at a speed you would consider normal, then you do not have any
interference. If it varies radically, you have interference.
>I don't actually have any connection problem it's just a general
>question so I know for the future and understand the situation better.
Good question. One of the common questions I see is "My wireless was
working just fine until a few days ago. Now, it's erratic,
disconnects often, slow, and useless. I didn't change anything".
Usually, that means the neighbors have dragged home a new wireless
router or wireless toy, and are creating interference. Being able to
recognize the difference between interference and simple
misconfiguration is useful.
>inSSIDer and xirrus wifi inspector show my router on channel 3, and I
>can select any from 1 to 11, so what do you mean?
Aaron Leonard answered that question effectively. The occupied
bandwidth (how wide the signal appears) is roughly 22MHz for
802.11a/b/g. At 5MHz per channel, that's a bit over 4 channels wide.
With 11 channels available, that's about 3 usable channels that do NOT
overlap each over.
Note that the degree of interference from adjacent channels depends
heavily on the distance between you and the source of interference. If
BOTH radios were in the same room, you might need more isolation than
if they were located in separate buildings.
>it's all very nice if of neighbourign routers, one is on 1, and one is
>on 11, then i go on 6. But a bunch are on 1, and a bunch are on 6, and
>a bunch are on 11.
>So what the heck, why not just choose 3?
Because you receive interference from others on both channels 1 and
channel 6. On a statistical basis, you'll be worse off than picking
either 1 or 6. In addition, you will be generating interference to
users of both 1 and 6, thus doubling the number of irate neighbors
banging on your door at odd hours.
>And also, let's suppose there is just one router and it's on 1,
>wouldn't a good use of space for me to put mine on channel 5?
>channels 1 and 5 don't overlap do they?
The channels are 5MHz wide. However, your signal is 22MHz wide.
>btw xirrus wifi inspector works nicely showing WPA and WPA2.
Cool. You might also try:
Unfortunately, it doesn't do a good job of identifying encryption
type, but does everything else well enough. To see interference
caused by non-802.11 devices, such as microwave ovens, you'll need a
Jeff Liebermann email@example.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558