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Bekijk de volledige versie : WiFi spectrum readings :)



wpte
12-10-2010, 16:46
So, I got hold of a wi-spy 2.4i
The cheapest wi-spy available, tho the hardware would probably cost you just 10%:p

Anyway, since I've never seen measurements (couldn't find anything on the forums) from the wifi of asus routers I thought it would be nice to do a little investigation.

The thing with wi-spys is, that it can't scan all channels at once, so I left every test running for 10minutes since it seemed a quite clear result after 10min.

Also, I ran the test in a microwave. Why a microwave? well... I thought it would act as a nice Faraday cage since it's quite crowded with wifi here:p
Now I did test if any noise would be generated with a router inside, but I couldn't find any difference, only many other AP's where filtered away a lot.

The firmware is oleg r2249 (from google code)

First of all, A screenshot from inside the microwave without my WL-500W running:
http://i55.tinypic.com/2rysh8y.jpg

WL-500W default settings:
http://i54.tinypic.com/2v8jxfp.jpg

WL-500W defaults, but with upper channel
http://i52.tinypic.com/w6z9nb.jpg

WL-500W defaults, but with lower channel
http://i55.tinypic.com/dq3pzk.jpg

WL-500W defaults, but only 20MHz (none channel)
http://i56.tinypic.com/204ac2.jpg

It's clearly visible the WL-500W generates a lot of noise around channel 6:confused:
But more interesting is that it seems like it doesn't matter how you set things up... it will always use a 40MHz bandwidth

For the people who can't see it, an smaller shot with lines I drawed:
http://i53.tinypic.com/25qgj61.jpg
Between the red lines is 20MHz, the yellow lines are an extention to 40MHz so that the WL-500W can serve 270Mbits

What do you think, more tests?:D
if anyone has a better idea for test setup let me know:)

p.s. not to be negative about oleg firmware & wifi obviously, I haven't seen results from other firmwares. Also it might be a good chance for wifi tweaking:D

theMIROn
13-10-2010, 06:48
nice test! thank you
whats about rt-n models?

wpte
13-10-2010, 12:04
nice test! thank you
whats about rt-n models?

I've only did a quick test on my rt-n16.
also I should put some load on the AP next time, it's supposed to create a flat line around the central channel:)

theMIROn
13-10-2010, 13:14
So, awaiting :)

wpte
13-10-2010, 18:26
So, awaiting :)

Did some tests on the RT-N16, and found out I really have to put load on it to make the true signal visible:)

Yet, for the ppl who like to see the raw values:
rt-n16 default: http://i52.tinypic.com/2rzuyib.jpg
rt-n16 upper: http://i55.tinypic.com/2i052jc.jpg
rt-n16 lower: http://i55.tinypic.com/2mpztpz.jpg
rt-n16 20mhz: http://i55.tinypic.com/2yukaco.jpg


Now, I measured the following results by downloading a file from the usb stick:D

defaults with load (channel 11, lower 2nd channel):
http://i55.tinypic.com/2zohhxx.jpg

lower, surprisingly it shows the higher channel is used.
central channel is 6:
http://i52.tinypic.com/14nd9hu.jpg

higher, surprisingly it shows the lower channel is used.
central channel is 6:
http://i54.tinypic.com/2po9us4.jpg

20MHz
http://i52.tinypic.com/2dkmwc6.jpg

for the 20mhz band it looks like it's just adding a secondary 20mhz band on the same frequency range

theMIROn
13-10-2010, 21:06
Great!
We've already discussed that choosen channel is the primary (control) channel, and upper/lower options means that exactly primary channel will be upper/lower, but not secondary or central.
So, I'm thinking about to change SubChannel name to something like Primary, or exchange lower/upper values. But the second will confuse users, am I wrong?

BTW, can you test official RT-N16 FW 1.0.1.9, there're changes related to wifi power saving.
They could change 20Mhz freq usage map, I hope.

wpte
13-10-2010, 22:12
Great!
We've already discussed that choosen channel is the primary (control) channel, and upper/lower options means that exactly primary channel will be upper/lower, but not secondary or central.
So, I'm thinking about to change SubChannel name to something like Primary, or exchange lower/upper values. But the second will confuse users, am I wrong?

BTW, can you test official RT-N16 FW 1.0.1.9, there're changes related to wifi power saving.
They could change 20Mhz freq usage map, I hope.

hmm... the control channel is the channel showing up on your wifi card right?
then why does the subchannel shift from the control channel in this picture: http://i55.tinypic.com/2zohhxx.jpg ? that parabolic line is drawn by the same software btw:p

Anyway, changing the subchannel name would probably be the easiest thing to understand I guess.

Maybe I have time to scan the official asus fw tomorrow, I also wonder what graphs dd-wrt produces:)

theMIROn
14-10-2010, 06:44
hmm... the control channel is the channel showing up on your wifi card right?
yep


then why does the subchannel shift from the control channel in this picture: http://i55.tinypic.com/2zohhxx.jpg ? that parabolic line is drawn by the same software btw:p
11 is higher control, 7 is lower sub and 9 is center channel. Whatz wrong? :)
http://en.wikipedia.org/wiki/IEEE_802.11n-2009#40.C2.A0MHz_in_2.4.C2.A0GHz

wpte
14-10-2010, 12:39
11 is higher control, 7 is lower sub and 9 is center channel. Whatz wrong? :)
http://en.wikipedia.org/wiki/IEEE_802.11n-2009#40.C2.A0MHz_in_2.4.C2.A0GHz

*slaps in his face*
yes, I was confused:p

wpte
22-10-2010, 17:16
I think my WiFi might be broken, got a packet loss of 30% or so:(

Time to send it back to let them repair it, good thing I never opened it up:D
should be done within 3 workdays, which is in holiday period for me, so after that I can measure it:D

wpte
28-10-2010, 16:10
I think my WiFi might be broken, got a packet loss of 30% or so:(

Finally, antennas where broken apparently:confused:

Anyway, I tried the original asus firmware, but I couldn't possibly get it into 40MHz mode:(

so the only result I got:
http://i56.tinypic.com/1sljio.jpg

The 20MHz band does look different than from oleg