Acoustic distance measurement test results

[quozl at laptop.org]

On Sun, Nov 18, 2007 at 06:01:22PM -0500, Benjamin M. Schwartz wrote:
> I also encountered some difficulty when sharing the activity over the
> mesh at distances greater than 25 meters.  This might be because the
> default mesh frequency (Channel 1) is the same as MIT's pervasive
> wireless network.  After switching to mesh channel 11, I had no
> difficulty sharing over distances up to 40 m.

Your observations are consistent with mine, subject to variables you
didn't mention.

How high off the ground were the laptops?  At ground height, with ears
up, the node to node transmission distance is very small.  That's why
school server antennas will be mounted high.

A football field normally has very little slope, so the terrain
obstruction is easily understood.

It might also be an area with a large radio noise background.  By
placing the laptops on the ground you may also have reduced the noise
from nearby transmitters.

With two laptops in a paddock or dirt road away from any city, I can
easily get to 300m on with the laptops at 1.5m above ground.

Nearby, I can reproduce 1.6km on a tar road with about 5% packet loss.

-- 
James Cameron    mailto:quozl at us.netrek.org     http://quozl.netrek.org/