Re: Link Quality

From: Eric Johanson (
Date: 2002-06-17 19:09:24 UTC

I've seen similar things on my p2p links.

I see a few things:

  1. Solar fading. Your 'night' time is much stronger. I've seen a change of about 8db snr due to sunlight, which almost matches what you have there.
  2. I see wind. One of the problems we had on our links was a not-so-well secured antenna. The wind would blow & knock it around. That may cause the big drops in your graph. How secure are your antennas?
  3. Dinner time. I see a 4-7 db drop in our links between 5 & 7 pm. It's all the microwave ovens in the area cooking up dinner. What's your wireless 'hood like? Countryside, or urban sprawl?

The only part of your graph I question is the stuff from 4-8 am. It seems strange that it would drop like a stone, and then creep back up again. My only theory is wind.

Hope this helps,

On Mon, 17 Jun 2002 wrote:

> I has tested P-t-P link (Compaq WL200 cards with outdoor antennas) which
> uses the IEEE 802.11 compliant IBSS mode and the hostap driver. The
> distance between stations is ~300 m. Between stations there are trees
> and couple of buildings. So no visual communication between them.
> I am wondering why my link quality is varying so much during the day
> (see the link-day.png attachment).
> Is the reason; sun, humidity or some other reason, other disturbing
> radio or ..? Any ideas ?
> The link quality may decrease from 36 to zero. When it is zero the data
> may still going (5.5Mb/s), but the link is breaking and there is a lot
> of RetryErr errors. Under this condition the diver resets
> the card. Dmesg shows COR resets.
> - Jar -

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