[manchesterwireless] Warrington Wireless - interference?

[G.W. Haywood]

Hi there,

On Thu, 27 Oct 2005, Andy Gauton wrote:

> Warrington Wireless celebrated it's 1yr anniversary of success.

:)

> Over a 12 month period ... only a couple of minor issues - solved by
> router reboot, usually remotely using Telnet :)

Telnet!???!!!  For goodness' sake junk it and use SSH!

> However, just as we were about to celebrate ... the network has been
> experiencing some major problems ... started noticing serious bandwidth
> issues ... recently 15k ... 900k, with the occasional 2MB+

> Went round the road with a laptop... VERY STRONG BT Voyager router
> signal on Ch8 ... Figures to be released once testing has been done
> over the next few days.
>
> Your thoughts please.

It's not just a matter of telling the devices which other devices they
should listen to, and which they should ignore, is it?  There is still
a clear line of sight between the antennae?  Nobody put a new extension
on their bathroom or anything?

Other thoughts:

1. Set up something to measure your signal strengths continuously.  See
   for example http://www.jubileegroup.co.uk/radio/powerbudget.html which
   shows some snow on an antenna, and if you think that the leaves on trees
   won't matter see http://www.jubileegroup.co.uk/radio/tree_trimmings.gif
   which shows the result of trimming a cherry tree (twice, on July 24 and
   August 21).   Also you'll see the effect of the sun shining on the black
   plastic box which contains the APs atop the mast in our installation -
   AP manufacturers don't seem to mention temperature coefficients much in
   their literature...  Incidentally I'd expect you to see better results
   in cooler parts of the year, other things being as equal as possible.
   Which they won't be, of course.
2. Write down some numbers for all the component parts.  For example "At
   20 deg. C we have +14dB from AP number 1, its sensitivity is -85dB, the
   antenna is a 16dB omni, there is about a 10dB loss between the connector
   on the antenna and the connector on the AP, the free space loss between
   AP1 and AP2 is -82dB because it's a distance of xxx.x metres."
3. Write down some more numbers for signals received from each AP by the
   other APs - and while you're at it, for signals received from elsewhere.
4. Don't imagine that ANY of your numbers will be constant, except maybe
   for the speed of light in vacuo.
4. Given the collection of numbers, decide what you think should happen.
5. If it's not happening:
6. Check the equipment performance, losses in the cables, connectors etc.
7. Try changing the antenna polarization.
8. Try using more directional/better antennae (my personal favourite.)
9. http://www.zytrax.com/tech/wireless/intro.htm (just found it, looks useful).

Let us know how you get on?

73,
Ged.

PS: Fill in the xxx above - that's a little test.