http://groklab.org/handhygiene/2009/08/20/prelim-testing/ Just another Groklab.org weblog Mon, 16 Aug 2010 14:54:45 -0400 http://wordpress.org/?v=2.8.1 hourly 1 http://groklab.org/handhygiene/2009/08/20/prelim-testing/comment-page-1/#comment-42 State of the Antenna Analysis « Hand Hygiene Thu, 22 Oct 2009 22:06:13 +0000 http://groklab.org/handhygiene/?p=13#comment-42 [...] Face to Face at 0.5, 1.0 and 2m, power 10, 15 and 20.  Conclusion – Things are going to be complicated.Rotating motes at 1.5m, power 20.  Conclusion – Orientation matters.Pairwise compatibility (redo) (best)- facing, 2m, power 20.  Comparison of signal strength of seven different motes. Conclusion – the motes are effectively interchangeable. The best test used 14 motes, 24″ apart and measured a between standard deviation of 3.7 and within of 0.64 RSSI value.Mote orientation – horizontal motes, 2m apart, 30-degree increments, power 10 and 20.  Conclusions – Large variation (30-60, 25-50 RSSI) in signal strength as a function of orientation.Mote Power level – vertical orientation, 2 rotations, 2 heights, 0.5, 1.0 and 2.0m apart, power levels 1-31.  Conclusion – the power level can be tweaked to separate various regions of the RSSI, such as providing greater separation between distances or orientations.Obstacle Interferance (inside puck) – one horizontal, one vertical, distance .55m. various obstacles:  person, wire, roomba (like a laptop).  Conclusion — these obstacles didn’t have much impact on the signal strength (< 1 or 2), except for the roomba, when put close to the mote.  In the inside versus outside puck conditions, we find that the plastic of the puck makes a small, but insignificant difference in the signal.Second orientation test – one mote horizontal, the other vertical, .55m separation, vertical mote rotated in 30 degree increments about 360 degrees.  Conclusion – in this configuration, the broadcast pattern is fairly reliable and smooth across a variety of power levels.  Angle of approach test – A worn mote versus the Purell.  The mote is worn in front at distances of .2 and .5 m and behind at a distance of .2.  Conclusion:  When behind at extreme angles, it was difficult to separate the signals.Full angle-height test (repeat with vertical transmitter) – Puck and badge orientation.  The first test with full statistics at 2 heights, 4 distances and 10 angles between 0 and 180.  The results indicate that it will be very difficult, if not impossible, to determine mote distance from the puck or vertical mote with a single RSSI reading at power level 3.  Perhaps .25m at the high level can be distinguished from others, but that is it. [...] [...] Face to Face at 0.5, 1.0 and 2m, power 10, 15 and 20.  Conclusion – Things are going to be complicated.Rotating motes at 1.5m, power 20.  Conclusion – Orientation matters.Pairwise compatibility (redo) (best)- facing, 2m, power 20.  Comparison of signal strength of seven different motes. Conclusion – the motes are effectively interchangeable. The best test used 14 motes, 24″ apart and measured a between standard deviation of 3.7 and within of 0.64 RSSI value.Mote orientation – horizontal motes, 2m apart, 30-degree increments, power 10 and 20.  Conclusions – Large variation (30-60, 25-50 RSSI) in signal strength as a function of orientation.Mote Power level – vertical orientation, 2 rotations, 2 heights, 0.5, 1.0 and 2.0m apart, power levels 1-31.  Conclusion – the power level can be tweaked to separate various regions of the RSSI, such as providing greater separation between distances or orientations.Obstacle Interferance (inside puck) – one horizontal, one vertical, distance .55m. various obstacles:  person, wire, roomba (like a laptop).  Conclusion — these obstacles didn’t have much impact on the signal strength (< 1 or 2), except for the roomba, when put close to the mote.  In the inside versus outside puck conditions, we find that the plastic of the puck makes a small, but insignificant difference in the signal.Second orientation test – one mote horizontal, the other vertical, .55m separation, vertical mote rotated in 30 degree increments about 360 degrees.  Conclusion – in this configuration, the broadcast pattern is fairly reliable and smooth across a variety of power levels.  Angle of approach test – A worn mote versus the Purell.  The mote is worn in front at distances of .2 and .5 m and behind at a distance of .2.  Conclusion:  When behind at extreme angles, it was difficult to separate the signals.Full angle-height test (repeat with vertical transmitter) – Puck and badge orientation.  The first test with full statistics at 2 heights, 4 distances and 10 angles between 0 and 180.  The results indicate that it will be very difficult, if not impossible, to determine mote distance from the puck or vertical mote with a single RSSI reading at power level 3.  Perhaps .25m at the high level can be distinguished from others, but that is it. [...]

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