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Anonymous(anon)
Posts: 0

Barometer not accurate?

I've gotten to play around with the barometer and I'm finding all the reading wrong, meaning none of them are correct.

For instance:

For the moment it is 1025.2hPa outside and my Xperia only shows 1014,3hPa

I've tested this with Barometer HD and Androisensors.

Can someone confirm that the readings are of?

Newbie
Ifor
Posts: 36
Registered: ‎2011-12-04

Re: Barometer not accurate?

Just checked here and I have a similar sort of offset.  There is a calibration option in Barometer HD which lets you put in an offset.  I am not sure what to expect. 

I primarily use the pressure sensor for altitude and with that you have to calibrate so an offset is not realy an issue.  I have not tested over a large altitude range so don't know if there are any slope issues.  I am out today for an extended bike ride checking battery usage over 5-6 hours.  There is a 400m hill in it so I will check the data in Ipbike after the ride to see how acurate it looks for that.

Newbie
Ifor
Posts: 36
Registered: ‎2011-12-04

Re: Barometer not accurate?

I just played some more with Barometer HD.  Having put the reported sea level pressure in, I have then modifed the calibration value to get the reported altitude to match my knowen altiude and I end up with having to put it back to zero.  So I don't think there i any offset required.  The problem is that reported readings wil normaly be for sea level pressure so unless you are at sea level you have to take that into acount.  The app sould realy have an option to let you enter your altitude and then reverse the calculation to enable it to display a local sea level pressure reading.

Trustee
Markus
Posts: 2,840
Registered: ‎2010-09-20

Re: Barometer not accurate?

I'll try to find some more information about the barometer and what to expect from it (and how to use the calibration option etc.). I will post here again when I have some information.

Inhabitant
higwayman
Posts: 243
Registered: ‎2010-06-29

Re: Barometer not accurate?

With due respect, this is not a simple topic and complex calculation involves.

It is not that as simple as what you describe.

Take for example when the GPS just arrives on the phone, people were complaining about the phone is not accurate. Actually it is the GPS which is not accurate. You can take the GPS and runs around a 400 meter track, you will find that at teh end of the run, the measured distance is less than 400m.

Like wise, these are not the most accurate tool to measure atmoshpere pressure. AT most and best, just an indicator. You cannot and you do not compare it with a mercury instrument.

"Atmospheric pressure is often measured with a mercury barometer, and a height of approximately 760 millimetres (30 in) of mercury is often used to illustrate (and measure) atmospheric pressure. However, since mercury is not a substance that humans commonly come in contact with, water often provides a more intuitive way to visualize the pressure of one atmosphere"

http://en.wikipedia.org/wiki/Atmospheric_pressure

Lets leave this topic. The reading is accurate enough!



Trustee
Markus
Posts: 2,840
Registered: ‎2010-09-20

Re: Barometer not accurate?

Sorry for taking so long, but here's some more info.

I'll just paste the info I got on this.

‘The device does contain a pressure sensor (barometric sensor)  and with some imagination this could be used for a number of functions depending on the application that was written and a barometer (in this case measuring atmospheric pressure)is certainly a possibility, a search of the Play Shop (Android Market) shows a number of applications using the pressure sensor in this way, accuracy will be dependent on the App and also that independent developers often welcome feedback on their app and contact details are found in the Play Shop to help them improve their App.’