

Your Phone Could Make You Into a Thunderstorm Predicting Machine - cryptoz
http://blogs.smithsonianmag.com/smartnews/2013/01/your-phone-could-make-you-into-a-thunderstorm-predicting-machine/?

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cryptoz
This article is about pressureNET, which is my open source Android app that
collects atmospheric pressure readings from sensors in phones and tablets. I'm
happy to answer questions as always :).

Edit: You can browse a visualization of our collected data from last year at
<http://pndv.cumulonimbus.ca> to get an immediate overview of our quantity and
quality of data.

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cameldrv
Can you tell us more about how you post-process the data? Given that you're
looking for small differences from what the nearest ASOS is reporting,
compensating for altitude and sensor calibration seems like a big challenge.

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cryptoz
At the moment we are not doing any post-processing. Our current approach is to
work with researchers at universities who specialize in the calibration of
pressure sensors like ours. We're talking with Cliff Mass at the University of
Washington, and as soon as we put out a new update to pressureNET with privacy
controls for our users, we will be streaming our data live to Cliff (and other
researchers who are interested). This is our primary short-term goal, as it's
the major hurdle we must overcome before pressureNET is a truly useful
product.

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aw3c2
please please if you give users the control, please let them also allow
completely free and open sharing. that way random interested hackers can play
with the data for random weekend projects and the like.

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cryptoz
Definitely! This project has the potentially to be immensely beneficial to
humanity, but only if it's open. So our code is open. But so far we've
struggled to make the data open out of privacy concerns, so we're not
_totally_ open yet. But open sharing of data is absolutely critical. So yes,
it'll be done, and done ASAP as well. We're hoping to have that update out
next week.

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preinheimer
A friend had a barometer on his watch in Highschool. We were out at the Ex
(large carnival/exposition in Toronto) and he watched the pressure plummet
over the course of an hour. We quickly made our way to the exit, and hopped on
the last train leaving before the downpour started.

It was a moderately silly looking watch, but I never mocked it again.

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miahi
I had one of these for years. It doesn't work every time (not every time the
pressure drops it will start to rain) but it helps you prepare.

I also have a barometer on the Galaxy Note phone. I tried some barometer
applications, but I could not find one that doesn't drain the battery even
when they are not showing data, so I stopped using them. The idea is great,
but the implementation of the applications and phone not so much - especially
when you compare it with a solar powered watch.

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pavel_lishin
Every time an exterior door in our office building opens, I can feel a strong
gust. Presumably this means that the air pressure inside a building is higher
than air pressure outside, right? How would this affect the data collected?

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cryptoz
The pressure indoors is usually very similar to the pressure outdoors, though
there are cases where it's different. A much bigger related issue for us is
altitude. The pressure by your feet is measurably different than the pressure
by your head due to the altitude difference. So you can imagine it's a lot of
noise as people move around and go upstairs, hills, etc.

We're working with researchers who are writing papers on the calibration of
networks of pressure sensor data (Cliff Mass' lab, specifically) in order to
help us solve this problem.

