third rural range test, ad-hoc mode

[Marcelo Tosatti]

Hi James,

On Fri, Jan 12, 2007 at 10:52:32PM +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?

-bash-3.1# iwlist eth0 txpower
eth0      8 available transmit-powers :
          5 dBm         (3 mW)
          7 dBm         (5 mW)
          9 dBm         (7 mW)
          11 dBm        (12 mW)
          13 dBm        (19 mW)
          15 dBm        (31 mW)
          17 dBm        (50 mW)
          19 dBm        (79 mW)
          Current Tx-Power=18 dBm       (63 mW)

-bash-3.1# iwconfig eth0 txpower 79mW
-bash-3.1# iwlist eth0 txpower
eth0      8 available transmit-powers :
          5 dBm         (3 mW)
          7 dBm         (5 mW)
          9 dBm         (7 mW)
          11 dBm        (12 mW)
          13 dBm        (19 mW)
          15 dBm        (31 mW)
          17 dBm        (50 mW)
          19 dBm        (79 mW)
          Current Tx-Power=19 dBm       (79 mW)

Apparently we have a bug here, 18 dBm is not reported in the list of
supported transmit powers.

Anyway, it would be very interesting to relate wireless transmit power
with system-wide power consumption.

> 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.

LOL :)