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Topic: altitude detector (Read 956 times) previous topic - next topic

dr_no

:smiley-zipper: i everyone...(nice day in paris !! )

i 'looking for an intgrated circuit who provide me the altitude of my position , i'dlike to feet it in my arduino uno , so if it is in i2c mode, it will be great.. XD

do you know circuits like this ?

best.....

astrofrostbyte

Since your not very clear on the range of altitude  cm's  or  100's meters  i'm just going to assume the latter.
I can thing of two methods:

  • a GPS module

  • an absolute barometric pressure sensor


Salut...
Gear: Arduino- Uno,Due,Ethernet,  OLS, Buspirate, J-Link, TDS1002, Rigol DG1022

MarkT

And further its worth knowing that GPS altitude information is complicated by the geoid.

The geoid is the shape of the gravitational equipotential corresponding to what is colloqually called sea-level.
It is not regular - it has lumps and bumps of several 100m all over the earth due to the varying density of
rocks in the earths crust.  GPS determines geometrical position and has to then correct for the local geoid
variation, which is done to much less accuracy than horizontal position (and different GPS units may do
different corrections and not agree with each other.)  Also since GPS satellites are typically over-head the
vertical positional accuracy with GPS is usually a lot less than horizontal accuracy anyway.

However GPS does measure absolute altitude.  Barometric sensing is affected by the weather so without
access to the local pressure at a reference altitude it isn't very useful - in aircraft the altimeter has to be
regularly reset according to the local weather information.  Barometric sensors are now very precise, being
able to measure pressure changes corresponding to less than 1m change in height (in the short term).
[ I won't respond to messages, use the forum please ]

dr_no

:smiley-zipper: thank you every one for the answers , i gona look for a simply solution;

i saw the MPL115A2 i2c cicruit,  :smiley-eek: i'm going to see if it's good for my apply...


midon

You might also want to look at the BMP085.  I've been using one very successfully to read altitude.  There's a tutorial located here: http://learn.adafruit.com/bmp085.

Mitch

Shpaget

I'd like to ask you to make sure really you need altitude and not height or elevation.
It could be an important factor in determining the best approach.

Boardburner2

Barometric sensors work well for rocketry, However they get zeroed at the location.
Driving around with one however can give very erroneous results, as others have pointed out local pressure variations affect them.

wwbrown

If all you want is relative difference in altitude between your location and some other location, say a low-altitude weather balloon, you can use a MPL115A2 on the balloon and one at your location and the difference in atmospheric pressures will tell you the difference in height.  Using the differential pressure method reduces the effects changes in the weather, note I said reduces the effects not eliminates.  After working on systems like this I can tell you the baro method of height estimation will be more accurate then the GPS method in the majority of cases.

dr_no

right ! 5u very much for all the aswers; here is my appli :

i want to detect in real time the altitude of my position during a travel in my car from point "a" to point"b" and i want to extract the values to get the final curve.

i only want to know what kind of detector is the best for this.....

many thanks... :smiley-mr-green:

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