[kismac] Re: Signal strength

  • From: Robin L Darroch <robin@xxxxxxxxxxxxx>
  • To: kismac@xxxxxxxxxxxxx
  • Date: Tue, 28 Feb 2006 22:56:00 +0800

Or another possibility - not quite sure how to do this - would be to let KisMAC auto-range: scale everything to 0-100 based on the strongest signal received by that device so far. Of course, it would need to remember that along with the individual driver entry in the preferences, and maybe allow a manual override? Essentially, start off with a mapping of 0-10 -> 0-100 (i.e. multiplier [m] = 10).

Now, if raw signal strength (reported by device) = r, and scaled strength = s,the algorithm goes like this:

s = mr
if (s>100) {
        s = 100
        m = 100/r

initially there would be lots of calls to the rescale function, but once it encountered one really strong signal, everything after that would result in s<=100, so existing data wouldn't need to be rescaled. That won't be very processor intensive, because even if we assume it happens 50 times before it finds a maximum that isn't beaten, we're still only talking about a simple multiplication. That way you know that 100 is the strongest that device has ever seen, and a 50 on an Airport Extreme is about the same as a 50 on a DWL-122.

At the end of each scan, store "m" along with the record of that particular driver.

Thoughts?  Anyone want to implement it? :)

Maybe an easier approach would be to allow the user to put in scale values themselves in the preferences for the driver? That way you wouldn't need to know about every card that comes a long. A user could infer what the scale is by having it shut off, then apply a mathematical factor after they say "my max is 40" or "my max is 125" ?

On 2/27/06, Robin L Darroch <<mailto:robin@xxxxxxxxxxxxx>robin@xxxxxxxxxxxxx> wrote:

To do that we'd have to develop a database of comparative strengths -
which would be pretty rough at best... but perhaps that's worth
doing?  I can tabulate Airport Extreme active vs. DWL-122 and Airport
Extreme passive vs. DWL-122... but only if the consensus is that it's
worth doing.

Or, if Kismac would "scale" it so it was consistent across adapters?

On 2/27/06, Geoffrey Kruse
<<mailto:<mailto:gkruse@xxxxxxxxxxxxxx>gkruse@xxxxxxxxxxxxxx><mailto:gkruse@xxxxxxxxxxxxxx>gkruse@xxxxxxxxxxxxxx> wrote:

I think this may be dependent on the driver.  For example, my usb
card seems to have a range of 0 to 40 while my airport extreme seems
to have a range of 0 to 100.  It would be nice if we used something
more standard like dbm.

On Feb 27, 2006, at 7:58 AM, Mike Williams wrote:

 in KisMAC and other WiFi apps there is the "Signal"-strength-
 number. From which number to which number does this go?
 The highest number I've seen was 101. Most networks are about 61
 and some are 31 or so.
 What is the smallest and the highest number that could appear?



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