[plug] [OT] Eftel Radiowan

[Michael Hunt]

> With my local 2.4 GHz WLAN I don't have line of sight on either link.
> There is a "Fresnel region" around the line of sight which must be clear
> for best transmission.  This is about 3 m across for my 150 m path
> lengths at 2.4 GHz.  With 11 dBA antennae I get a reliable, if not good,
> signal strength with about 50% of this region obscured with trees.
>
> K.

Could you explain in a bit more detail what is actually meant by "line of
sight" in the context of wireless networking ? The reason I ask is that I am
interested in connecting two sites together that are located about 5kms
apart with a natural obstacle (the Niger river) running between the two. One
is fairly close to the river in a bit of a hollow with the other being up a
bit higher. There is only one tall building in the city but there are quite
a few trees at each location.

We are currently using Codan gear to connect one of these locations with a
hospital over 500kms away. The codans use HF channels assigned to us by the
government and talk to each other at roughly 6000bps depending on conditions
and amount of compression . I'm in the process of setting up a freesco
router box in order to allow TCP/IP networking to happen between the two.