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Author Topic: Low power wireless sensors  (Read 2266 times)
djh
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« on: September 15, 2010, 04:25:31 PM »

Just seen this:

http://ubicomplab.cs.washington.edu/wiki/SNUPI

This work explores the use of the home powerline as a large distributed antenna capable of receiving signals from ultra-low-power wireless sensor nodes and thus allowing nodes to be detected at ranges that are otherwise impractical with traditional over-the-air reception. We developed and tested an implementation of small ultra-low-power 27 MHz sensor nodes that transmit their data by coupling over the powerline to a single receiver attached to the powerline in the home. This general purpose wireless sensing platform provides whole-home coverage while consuming less than 1 mW of power when transmitting (65 μW consumed in our custom CMOS transmitter). This is the lowest power transmitter to date compared to those found in traditional whole-home wireless systems.

Full details in
http://sockeye.cs.washington.edu/research/pubs/Cohn_SNUPI_ubicomp10.pdf
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Cheers, Dave
Ivan
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« Reply #1 on: October 10, 2010, 02:24:35 AM »

Is that using a 'powerline modem' to input / extract the signals from the powerline? In which case you need to add 2-6W at each end?
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ericw
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« Reply #2 on: October 10, 2010, 04:51:15 PM »

Ivan,
The idea seems to be using the powerline as a RF coupling medium rather than air. They couple the TX outputs to the line and use normal RX technology to pick up the signal.
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djh
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« Reply #3 on: October 11, 2010, 03:41:03 PM »

Err, I haven't reread it to check but my understanding is that the transmitters are free-standing and battery-powered. It's the receiver that is attached to the mains and which uses it as a large antenna to receive the signals. It enables the use of lower transmitter power partly because the distance from the transmitter to the mains is typically shorter than that from the transmitter to the receiver and partly because the mains cable is a more efficient antenna at the chosen frequencies than the usual small bit of wire (such as in my Drayton wireless thingy).

There are some other clever tricks used to reduce the power requirements so that the battery should last for many years. I expect the receiver gets its power from the mains. Transmitter power really is 65 μW
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Cheers, Dave
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