>I have a 5 mile 802.11b link that works fine until air
>temperatures exceed around 85 F. Over a period of about
>an hour, the percentage of missed pings


In broadcast television studio transmitter links (STL's) are frequently
designed with 'spatial' diversity for just this reason. By that I mean
you would have two separate antennas spaced some vertical distance
apart. A comparator in the receiver looks at each signal and makes a
determination about which 'path' to use. Why go through this obvious
explanation? Lots of time temperature inversions can create layers in
the atmosphere that can change the path characteristics. This can result
in the kind of periodic path changes you are seeing and are due to
changes in the density of the atmosphere along the link. Fly into the
Los Angeles basin on any hot smoggy day and the inversion layer becomes
glaringly obvious. Wake up in the south bay region (Torrance, south of
LAX) and you get something called 'June gloom'. The marine layer pushes
in and can force hotter air layers up the mountain passes.

Cheers,
Chris Spacone
www.infosci.com


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