TXPOWER has no impact on ZCOM XI-325H (final report)

[Pavel Vondricka]

> So what difference were you able to measure? What did you use for
> measurements?

It was very simple. The build-in antennas didn't help very much, the signal 
was almost the same or changig too much by itself. We used two notebooks, 
each with one card (XI-325 and XI-325H). Later we tried to cennect a 
directional antenna (about 16-18dB) to the transmitting card (Linux+hostap). 
The receiving notebook (Win+NetStumbler) was across a hall in another room 
(at least 5m distance, may be more). When the receiving computer stayed 
without movement and I changed the txpower, we could see in NetStumbler 
graphical view of the received signal steps going down, as I changed the 
txpower from 20 to 10,0,-10,-20,aso. The steps were not linear - first steps 
were small about a few dB, then may be greatest when going down from 10 to 0 
(or 0 to -10?) of about 15dB. I think it would be better to measure somewhere 
outside.

At the end my friend just moved the notebook (on the lap) a little bit and the 
signal strength went up by some 10-20dB again without any change. When he 
moved the notebook back to about the same position, the signal came down to 
the same level as before. Nevertheless I hope our results were not 
accidental, because the signal was in the stable position really quite stable 
and the "steps" in the graph were stable, even though short (just a few 
seconds). But he has done some measurements with his XI-626 in his room and 
the results were similar. So I think the problems we had were caused by the 
omnidirectional build-in antennas and maybe reflecting walls(?). 

>
> Wed, Dec 18, 2002 at 12:17:32AM -0100 Pavel Vondricka wrote about Re:
> TXPOWER has no impact on ZCOM XI-325H (final report)
>
> > Final report for concerned:
> >
> > Today we tested both XI-325 and XI-325H and it seems that the first one
> > really can control it's output power, but not the second one. The
> > conditions were quite strange - the signal changed much more just by
> > itself (maybe strong reflections from the concrete walls?). A small
> > movement with a notebook made much greater change in signal strength than
> > any regulation, however there really were some visible changes in the
> > strength, when the situation got stable. But there was no change with the
> > XI-325H at all.

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