

Pocket Meteorology: Using Android Phones to Crowdsource the Weather - exap
http://weathersignal.com/

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cryptoz
This is very similar to pressureNET, my open source Android app that collects
pressure data and sends it to atmospheric science researchers. I'm quite
excited that there's competition and that it looks good! If you're reading
this, good job WeatherSignal!

pressureNET:
[https://play.google.com/store/apps/details?id=ca.cumulonimbu...](https://play.google.com/store/apps/details?id=ca.cumulonimbus.barometernetwork)

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nmb
I actually thought this post was about pressureNET at first :)

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albertyw
One thing that I think would be amazing would be using gps and/or cell radio
signals to do a very rough estimation of atmospheric conditions. Having done a
bit of research with in geodesy at MIT, I remember using Trimble GPS receivers
to track continental drift but having to account for environmental (mostly
atmospheric) effects adding noise to our GPS readings. With a bit of low level
signals processing, I believe it'd be possible to make plausible weather
readings based on the noise in GPS receivers, though having done little mobile
development, I'm not sure whether the Android OS would allow such low level
access to GPS chips (or if the chips themselves are precise enough for the
noise to come from the signal rather than the chip itself).

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eyeface
On the dashboard, there are four measures: Temperature, Light, Pressure, and
Magnetic Flux. I know that my phone (Galaxy Nexus) has the last three, but I
wonder where the temperature data is coming from. The only temperature data I
can find with AndroSensor is the battery temperature. Are all these values
live readings of my sensors?

[edit] I should note that the temperature on the dashboard is ~85 degrees
Farenheit, when the current temperature is about 20F lower.

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philjones
They're using the battery temperature run through an algorithm they've devised
which they've found to, when averaged with other local users, estimate the
actual temperature. My phone's been charging since I installed the app and
that skyrockets the battery's temperature, so I have yet to see it give a
remotely accurate reading of the ambient temperature.

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brendan_gill
Yes, this is how we do it. It's going to be quite rough for an individual user
for an individual moment in time but we've shown that averaged over many users
that battery temperature is closely correlated with the ambient environmental
temperature. You should see greater accuracy when your phone has been
relatively idle and reached an equilibrium with the environment whereas if
your phone has been whirring through cpu cycles the accuracy will decrease.

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xwowsersx
Kinda weird that the phone image shows a Galaxy S3 with physical back and home
buttons, but then shows the software buttons...

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csmatt
Is this the intended use of the barometric sensors on phones like my Nexus 4?

Can anyone think of other uses?

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albertyw
I'm pretty sure the barometers are meant to be used for predicting height
(i.e. as an altimeter) so that the phone can get a GPS lock more easily.

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csmatt
Interesting. Didn't know that. Thanks!

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brendan_gill
Yep, using pressure to gauge height is how many altimeters work. Then by
removing this degree of freedom your phone is able to calculate a GPS location
quicker as it knows you are confined to a particular area as opposed to a
volume. I believe it also means you can get a GPS location when locked to one
fewer satellites (though it may be slower in this situation).

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tlongren
Wish they'd just use the pressureNET data, since it's publicly available.

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nivertech
I don't think that their data is publicly available

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cryptoz
We provide a livestream API to researchers only right now:
<http://pressurenet.cumulonimbus.ca/livestream/>. We haven't yet opened to
businesses yet because our new open source SDK is going to change our API
quite a bit, so we want to stabilize it first. We're interested in this type
of partnership however, and look forward to opening this up in the coming
days/weeks. SDK code is about 90% feature complete and totally stable, so
we're almost ready.

<https://github.com/CbSoftware/pressureNET-SDK>

