[kismac] Re: Signal strength

  • From: Brad Knowles <brad@xxxxxxxxxxxxxxxxxxx>
  • To: kismac@xxxxxxxxxxxxx
  • Date: Thu, 2 Mar 2006 00:26:58 +0100

At 6:39 AM +0800 2006-03-02, Robin L Darroch wrote:

 In this case, the POLA is actually to provide auto-scaling, not the raw
 values KisMAC currently shows.

You've generated one case where auto-scaling appears to work. Take any scheme in the world, and it's trivially easy for anyone to come up with a single case where the scheme appears to work.

What's hard is generalizing the scheme to the point where you can prove beyond a reasonable doubt that it covers at least the vast majority of cases, and at least has reasonable failure modes for the other cases.

 Yes, it should be optional to turn it on, but I don't think the fact that
 it might be used to make an inappropriate comparison is a reason to exclude
 it from the program altogether: we already present data that will give
 wildly inaccurate comparisons, and don't even warn people that they
 shouldn't compare.

In many cases, you'll get wildly different numbers with exactly the same computer, exactly the same card, exactly the same position, and exactly the same transmitter. Wireless networking is just funny that way -- sometimes someone next door turns on the microwave, or a digital cordless phone might be in use, or a cordless video sender might be turned on, and those are just the most obvious RFI sources I can think of off the top of my head.

I don't think we should be causing the situation to be even more confusing to people by adding yet another factor that could throw everything totally off.

 Hmm... this is getting a bit big... but the more I think about it, the
 more convinced I am that it would be a considerable improvement to the
 current numbers we show - we just need to be sure to get it right.

At the very least, if you're going to do it, please make sure that it's not turned on by default, and that it's difficult to accidentally turn on, and that you provide suitable warnings to people if they do decide to turn it on.

 This doesn't exclude the possibility of using dBm if/when we can gather
 data on translating raw signals to dBm for all supported adapters: just
 let the user choose - raw, dBm, or auto-scaled.

I'd be much more interested in seeing work done on dBm first, and I'm sure there are lots of other good things that could be worked on before auto-scaling, but then I'm not the one writing the code.

Brad Knowles, <brad@xxxxxxxxxxxxxxxxxxx>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

    -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
    Assembly to the Governor, November 11, 1755

 LOPSA member since December 2005.  See <http://www.lopsa.org/>.

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