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Seeing a reverse sawtooth-shaped noise spike in OS X Wi-fi Diagnostics that is associated with wireless connection drops. My wireless router is old, so it might just be dying. It seems to be somewhat random, and more of a problem when I'm farther away from the wireless router, probably due to the decreased signal level, but I might be imagining that.

Is this spike similar to what you'd see with a problematic, old wireless router? If not, what are other likely causes (bad firmware update, router config issues, external source causing noise)?

Also, what would be a likely reason for the almost immediate increase in noise intensity, followed by a mostly linear drop in noise strength back to normal for an extended time?

Sawtooth-shaped signal noise as shown in the OS X Wireless Diagnostics application

Update: Just replaced the router, and the noise spikes are still occurring.

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Do you have a microwave or any other devices that put out radiation or operate on or near the wireless frequency? – Rachel Nark Mar 26 '13 at 18:10
Do your neighbors? – Sam Axe Mar 26 '13 at 18:11
Also TV channel changers that work between rooms, video repeaters, and baby monitors. – Col Mar 26 '13 at 18:14
I have one new appliance, but it's a fridge, not a microwave. So, afaik, I don't have a microwave or any other devices nearby that put out radiation or operate on or near its frequency when the connection is dropping. – Gary S. Weaver Mar 26 '13 at 18:16
i only recently found out even a misplaced new mirror on a wall may interrupt certain channels of transmission on wireless routers. tested and confirmed. – Lorenzo Von Matterhorn Mar 26 '13 at 19:30

common wireless devices like portable phones, Indoor/outdoor thermometers, analog AV rebroadcasters, are a common source of interference. non-wireless devices like florescent lights, microwaves, and even high power speakers can cause spikes in noise in unexpected bands.

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I did replace a florescent bulb in the house recently, but it doesn't make any strange intermittent noises. I think more likely than not, it is the wireless router itself, but I'm not ruling out external sources like the ones mentioned. – Gary S. Weaver Mar 26 '13 at 18:20

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