The Linear Regression approximation was exactly what we were trying to do.
Didn't know about the indoor limitations.
Please do clear this one doubt for us though - We were taking these
measurements at increments of 1 inch corresponding to about 15 seconds on
the curve that I attached in the previous email (the initial position was
at 1inch from the chirp mote). We did try taking these measurements at a
height off the floor (held by hand at shoulder level) and at floor level.
The curve didn't show any significant differences. The floor in question
is in a huge warehouse that we use as a testbed - it's devoid of furniture
save for the odd computer or two. Is this behaviour still normal?
Thank you for your help.
Sankar.
On Fri, 21 Apr 2006 03:26:32 -0500, Roberto <[EMAIL PROTECTED]> wrote:
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Hi,
there is not a close relation RSSI-distance if you are using motes in
an indoor environment, I mean, in outdoor we have a lognormal
relation. But in indoor, if the motes are not close (distance < 1
meter) the RSSI is not always a decreasing function of the distance,
due to multipath fading, obstacles such as furnitures and so on... You
could do a set of measurements and obtain a linear regression forumula
but, in general localization algorithms with some sort of model of
indoor propagation will fail, due to this fact.
The message->strength field return the rssi in dbm (complement 2
notation). The correct value is obtained with message->strength - 45
(45dBm is a preamp gain of the receiver).
regards
Roberto
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