So microwaves really do fubar wireless

spidey07

No Lifer
Aug 4, 2000
65,469
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Just for giggles I was playing around with an analzer just to see how things looked. Relatively quiet, 3 access points at around -70 to -90 dBm. There was a microwave nearby. Turned it on for 10 seconds just for fun. This was a commercial one normally seen in an office environment.

WOW! Did it ever obliterate the specturm. Nothing but noise at -35 dBm.

So no joke, they don't play well with 802.11g

 

cmetz

Platinum Member
Nov 13, 2001
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spidey07, the Lucent WaveLAN 802.11 gear has a whole feature called "microwave oven avoidance" or something of the sort, where if it sees the telltale signs of microwave oven leakage, it hops channels. As far as I know, no other vendors really handle this case right.

It is not coincidental that the ISM band at 2.4GHz is a public/license-free band. It was originally considered to be basically useless for communications, between the whole water thing and microwave ovens that are usually at 2.45GHz but leak *all* over. (for a good time, try putting a TV or radio antenna near a microwave oven, guess what that does to reception, even today. I wouldn't exactly hang out in front of the microwave oven if I were you!)
 

Madwand1

Diamond Member
Jan 23, 2006
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Here's a performance trace I just did at home across an 802.11g bridge, turning on the microwave midway for 20s. This isn't too bad actually, I remember worse:

F:\tools\bench\iperf>iperf -c smallserver -t 500 -l 64k -i 3
------------------------------------------------------------
Client connecting to smallserver, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[668] local 192.168.0.141 port 39524 connected with 192.168.0.144 port 5001
[ ID] Interval Transfer Bandwidth
[668] 0.0- 3.0 sec 6.56 MBytes 18.4 Mbits/sec
[668] 3.0- 6.0 sec 5.06 MBytes 14.2 Mbits/sec
[668] 6.0- 9.0 sec 6.63 MBytes 18.5 Mbits/sec
[668] 9.0-12.0 sec 6.63 MBytes 18.5 Mbits/sec
[668] 12.0-15.0 sec 6.13 MBytes 17.1 Mbits/sec
[668] 15.0-18.0 sec 6.69 MBytes 18.7 Mbits/sec
[668] 18.0-21.0 sec 6.75 MBytes 18.9 Mbits/sec
[668] 21.0-24.0 sec 6.69 MBytes 18.7 Mbits/sec
[668] 24.0-27.0 sec 6.63 MBytes 18.5 Mbits/sec
[668] 27.0-30.0 sec 1.50 MBytes 4.19 Mbits/sec
[668] 30.0-33.0 sec 384 KBytes 1.05 Mbits/sec
[668] 33.0-36.0 sec 576 KBytes 1.57 Mbits/sec
[668] 36.0-39.0 sec 576 KBytes 1.57 Mbits/sec
[668] 39.0-42.0 sec 576 KBytes 1.57 Mbits/sec
[668] 42.0-45.0 sec 896 KBytes 2.45 Mbits/sec

[668] 45.0-48.0 sec 6.50 MBytes 18.2 Mbits/sec
[668] 48.0-51.0 sec 6.69 MBytes 18.7 Mbits/sec
[668] 51.0-54.0 sec 6.69 MBytes 18.7 Mbits/sec
[668] 54.0-57.0 sec 6.50 MBytes 18.2 Mbits/sec

Guess I could think about shopping for a a microwave with a spectrum analyzer in hand or setting up a Faraday cage around the kitchen. Hmm. Or maybe just run a wire..
 

Megatomic

Lifer
Nov 9, 2000
20,127
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Yeah, I can always tell when my kids are using the microwave, I lose connection with my 2wire wireless dsl router. I wonder if 802.11n suffers from this like my 802.11g does?
 

spidey07

No Lifer
Aug 4, 2000
65,469
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Originally posted by: Megatomic
Yeah, I can always tell when my kids are using the microwave, I lose connection with my 2wire wireless dsl router. I wonder if 802.11n suffers from this like my 802.11g does?

I'm sure it does. Same spectrum. As far as I'm concerned the 2.4 spectrum is dead.

The 5 Ghz and 90 Ghz are where it's at.