This time there was one mote held vertical with the usb pointing upwards while the other was horizontal. The two motes were placed .55 meters away from each other and the horizontal mote was spun around 360 degrees with a resolution of 10 degrees. This was a preliminary test because we have not checked for any other wireless activity in the area yet so there may be some sort of
interference. Here is a plot of the rssi for several different power levels at each angle, with zero degrees when the horizontal usb is pointing towards the vertical mote: 
This second plot is of the standard deviation of the rssi at certain power levels. It is easy to see that that most of the standard deviation appears to be random, but there is a spike at zero degrees. Now that I think about it, the point marked 0/360 degrees is when the horizontal motes antenna is pointed away from the vertical, which probably explains the low rssi at these points. 
Nicely done, Derek. I’m impressed with how quickly you figured this out and got some data!
My first thought was that the standard deviation spike might be caused by the low RSSI values at 0 degrees. If the variation is relatively constant, the smaller signal leads to greater standard deviation.
I notice that the change in RSSI levels (the slope of the top graph — kind of) is greatest near zero. Is it possible that small changes in orientation might have caused the standard deviation? I’m guessing no, because you probably had the motes in a fixed physical position during each power-level/orientation condition.
Comment by gthomas — September 16, 2009 @ 10:34 am
Are the power levels on the std deviation graph right? I’m surprised that power level 10 has a high std dev than power level 5. May be noise, or may be that my hypothesis about a constant noise level is wrong.
Comment by gthomas — September 16, 2009 @ 10:38 am
Sorry, one more thought. Did you compare it to the previous results? Similar or different?
Comment by gthomas — September 16, 2009 @ 10:46 am
Esto es poco probable.
Comment by cubrikaska — October 5, 2009 @ 2:45 am
Why do you say that?
Comment by gthomas — October 5, 2009 @ 11:46 am