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- Why does signal strength fluctuate
July 11, 2007, 5:34 pm
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Re: Why does signal strength fluctuate
Reflections. Signals don't only go directly from one place to
another. At 2.4GHz, they bounce around quite a bit. When the various
paths converge at one point, they sometimes cancel and sometimes add.
These reflections are not stable as things do tend to move around.
Done properly, you can actually move a metal reflector around until
you have a deep null (no signal) or a spectacular peak.
What else is moving around during the day? If the two radios can see
each other directly, you'll have a fairly solid and stable signal.
However, if you're shooting through a wall or two, or have highly
reflective (metal) environment, it's going to vary. How much
variation is difficult to predict.
Ideal size for a 2.4GHz reflector is 1/2 wave which is about 6.25cm.
Therefore, it doesn't take much metal to make a fairly good reflector.
You can improve things by NOT using an omndirectional antenna, which
has the worst time with reflections to/from all directions. A
reflector or directional antenna will be a big help instabilizing the
signal. Since the client end is stationary, that's fairly easy to do
depending on what you're using for hardware.
You might also want to fire up Netstumbler and watch the signal
strength change as you walk around the room. I can see signal
strength changes as cars drive by outside my office picture window
perhaps 10m away.
Jeff Liebermann firstname.lastname@example.org
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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