[MLB-WIRELESS] 802.11b channels question...

[paul van den bergen]

On Thu, 8 May 2003 08:03 am, Rowan Crowe wrote:
> > > ch 14 centred at 2.484 (2.473 - 2.495)
> > >
> > > so ch14 is clear of the top of ch 11.
> > >
> > > so that seems to indicate that if we select ch 1, 6,
> > > 11 and 14, we will have 4
> > > clear channels!!!!
>
> Sounds like a good plan, I was going to set everything to ch14 and reduce
> the power on my AP, hoping to use it as a low powered 'indoor only'
> channel. However, the 900AP+ only allows me to select 1-13. :(
>
> This is with the AU firmware (2.5), the US firmware may permit selection
> of channel 14. Anyone?
>
> (this is just a wild guess, but 14 is probably disallowed in the firmware
> for a reason :P... )

I seem to recall something vaguely along the lines of that is what the 802.11 
card I have at home used... I was going to check the cards I have at home 
last night but forgot...

according to ieee 802.11 1999 spec. the frequency range is the same regulatory 
limits of the ISM band, geographically, as 802.11b, not surprisingly. 
However, the channels are 1 MHz wide and there are 95 of them - from 2.401 
GHz to 2.495 GHz - and the hopping sequence goes from channel to channel, 
rather than within a channel - e.g. FHSS. I think? spectrum and transmission 
techniques are not my strong point :-)

so I still have no clear idea as to why channel 14 is so diferent to the 
others.

BTW, wasn't the 200mW limit on the upper channels lifted recently in 
Australia? Will have to check...


-- 
Dr Paul van den Bergen
Centre for Advanced Internet Architectures
caia.swin.edu.au
pvandenbergen at swin.edu.au
IM:bulwynkl2002
"And some run up hill and down dale, knapping the chucky stones 
to pieces wi' hammers, like so many road makers run daft. 
They say it is to see how the world was made."
Sir Walter Scott, St. Ronan's Well 1824 

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