We’ve built a circuit to count the number of times someone can enter and leave through a doorway. The circuit runs 0n a 9V battery and a separate battery to power a mote. I wondered if the battery would last a full 24 hours, we set the sender and receiver up with a little robotic arm that interrupts the beam every few seconds. The program runs for either 28 or 23 hours without stopping (there is a period of uncertainty after the first five hours and I’m not sure if Gregg restarted the test or simply adjusted the arm to interrupt the beam — but I’d guess the later). I’ve restarted the test to get another number.
January 11, 2010
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It should be 28 hours. There was one point where the motes shifted positions so that the beam was not making contact between them. This corresponds to the period in the data file when the motes were only sending the heartbeat signals, and not telling when the beam was being interrupted. When I noticed this, I corrected their positions.
-Gregg
Comment by gscranton — January 12, 2010 @ 2:45 pm
Further analysis of the data shows that about 20 minutes before the batteries run out, it begins to broadcast nonexistent events, possibly because the beam is becoming weak. The number of disruptions of the beam during the test should also be noted, in this case about 6300.
Comment by gscranton — January 12, 2010 @ 3:56 pm