third rural range test, ad-hoc mode

Jim Gettys jg at laptop.org
Fri Jan 12 07:10:51 EST 2007


James,

I don't know how to express our thanks properly for these tests.  And
it's wonderful you are getting your exercise doing them!

It would be interesting, in an academic sort of way, to also try a
"conventional" laptop with built-in internal wireless as an independent
"control".

Looking forward to seeing next week at LCA!  I arrive Tuesday; Chris
Blizzard arrives Sunday.
                                Best Regards,
                                          - Jim

On Fri, 2007-01-12 at 22:52 +1100, James Cameron wrote:
> G'day,
> 
> The earlier test today was on slightly undulating terrain, plus or minus
> half a metre, which made quite a difference to communication between the
> units.  Pings were lost in a dip at about the 800m mark.
> 
> I still felt the need for exercise, so I did another test, on another
> range, this time a sealed road section 1.3km long with slightly raised
> ends (2m), and no undulation, so that terrain wasn't as much of a problem.
> 
> The two laptops communicated fine over 1.3km, with the same 10 Hz ping,
> also carrying a 44100 Hz audio stream of wind noise in WAV format over
> SSH.
> 
> Signal level was -83 dBm, noise level was -89 dBm, bit rate shown by
> iwconfig was oscillating between 5.5 Mb/s and 11 Mb/s for the unit
> transmitting the audio stream, and 1 Mb/s to 2 Mb/s for the unit
> receiving.
> 
> Are there any transmit power knobs to twiddle?
> 
> Now I shall have to find a longer road ... and maybe get someone to
> drive me over the range rather than walk it ... the road goes ever on
> and on ...  met a black snake on the way back, warming itself on the
> surface, but it wasn't interested in the project.  Nor was the wallaby
> or the rabbits.  The flies were interested, though.
> 
-- 
Jim Gettys
One Laptop Per Child





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